Publisher: Elsevier   (Total: 3206 journals)

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Showing 1 - 200 of 3206 Journals sorted alphabetically
Academic Pediatrics     Hybrid Journal   (Followers: 39, SJR: 1.655, CiteScore: 2)
Academic Radiology     Hybrid Journal   (Followers: 27, SJR: 1.015, CiteScore: 2)
Accident Analysis & Prevention     Partially Free   (Followers: 106, SJR: 1.462, CiteScore: 3)
Accounting Forum     Hybrid Journal   (Followers: 28, SJR: 0.932, CiteScore: 2)
Accounting, Organizations and Society     Hybrid Journal   (Followers: 44, SJR: 1.771, CiteScore: 3)
Achievements in the Life Sciences     Open Access   (Followers: 8)
Acta Anaesthesiologica Taiwanica     Open Access   (Followers: 6)
Acta Astronautica     Hybrid Journal   (Followers: 450, SJR: 0.758, CiteScore: 2)
Acta Automatica Sinica     Full-text available via subscription   (Followers: 2)
Acta Biomaterialia     Hybrid Journal   (Followers: 30, SJR: 1.967, CiteScore: 7)
Acta Colombiana de Cuidado Intensivo     Full-text available via subscription   (Followers: 3)
Acta de Investigación Psicológica     Open Access   (Followers: 2)
Acta Ecologica Sinica     Open Access   (Followers: 11, SJR: 0.18, CiteScore: 1)
Acta Histochemica     Hybrid Journal   (Followers: 5, SJR: 0.661, CiteScore: 2)
Acta Materialia     Hybrid Journal   (Followers: 337, SJR: 3.263, CiteScore: 6)
Acta Mathematica Scientia     Full-text available via subscription   (Followers: 5, SJR: 0.504, CiteScore: 1)
Acta Mechanica Solida Sinica     Full-text available via subscription   (Followers: 9, SJR: 0.542, CiteScore: 1)
Acta Oecologica     Hybrid Journal   (Followers: 12, SJR: 0.834, CiteScore: 2)
Acta Otorrinolaringologica (English Edition)     Full-text available via subscription  
Acta Otorrinolaringológica Española     Full-text available via subscription   (Followers: 2, SJR: 0.307, CiteScore: 0)
Acta Pharmaceutica Sinica B     Open Access   (Followers: 2, SJR: 1.793, CiteScore: 6)
Acta Psychologica     Hybrid Journal   (Followers: 26, SJR: 1.331, CiteScore: 2)
Acta Sociológica     Open Access   (Followers: 1)
Acta Tropica     Hybrid Journal   (Followers: 6, SJR: 1.052, CiteScore: 2)
Acta Urológica Portuguesa     Open Access   (Followers: 1)
Actas Dermo-Sifiliograficas     Full-text available via subscription   (Followers: 3, SJR: 0.374, CiteScore: 1)
Actas Dermo-Sifiliográficas (English Edition)     Full-text available via subscription   (Followers: 2)
Actas Urológicas Españolas     Full-text available via subscription   (Followers: 3, SJR: 0.344, CiteScore: 1)
Actas Urológicas Españolas (English Edition)     Full-text available via subscription   (Followers: 1)
Actualites Pharmaceutiques     Full-text available via subscription   (Followers: 7, SJR: 0.19, CiteScore: 0)
Actualites Pharmaceutiques Hospitalieres     Full-text available via subscription   (Followers: 3)
Acupuncture and Related Therapies     Hybrid Journal   (Followers: 8)
Acute Pain     Full-text available via subscription   (Followers: 15, SJR: 2.671, CiteScore: 5)
Ad Hoc Networks     Hybrid Journal   (Followers: 11, SJR: 0.53, CiteScore: 4)
Addictive Behaviors     Hybrid Journal   (Followers: 18, SJR: 1.29, CiteScore: 3)
Addictive Behaviors Reports     Open Access   (Followers: 9, SJR: 0.755, CiteScore: 2)
Additive Manufacturing     Hybrid Journal   (Followers: 14, SJR: 2.611, CiteScore: 8)
Additives for Polymers     Full-text available via subscription   (Followers: 22)
Advanced Drug Delivery Reviews     Hybrid Journal   (Followers: 193, SJR: 4.09, CiteScore: 13)
Advanced Engineering Informatics     Hybrid Journal   (Followers: 13, SJR: 1.167, CiteScore: 4)
Advanced Powder Technology     Hybrid Journal   (Followers: 17, SJR: 0.694, CiteScore: 3)
Advances in Accounting     Hybrid Journal   (Followers: 9, SJR: 0.277, CiteScore: 1)
Advances in Agronomy     Full-text available via subscription   (Followers: 20, SJR: 2.384, CiteScore: 5)
Advances in Anesthesia     Full-text available via subscription   (Followers: 30, SJR: 0.126, CiteScore: 0)
Advances in Antiviral Drug Design     Full-text available via subscription   (Followers: 2)
Advances in Applied Mathematics     Full-text available via subscription   (Followers: 12, SJR: 0.992, CiteScore: 1)
Advances in Applied Mechanics     Full-text available via subscription   (Followers: 12, SJR: 1.551, CiteScore: 4)
Advances in Applied Microbiology     Full-text available via subscription   (Followers: 24, SJR: 2.089, CiteScore: 5)
Advances In Atomic, Molecular, and Optical Physics     Full-text available via subscription   (Followers: 15, SJR: 0.572, CiteScore: 2)
Advances in Biological Regulation     Hybrid Journal   (Followers: 4, SJR: 2.61, CiteScore: 7)
Advances in Botanical Research     Full-text available via subscription   (Followers: 2, SJR: 0.686, CiteScore: 2)
Advances in Cancer Research     Full-text available via subscription   (Followers: 35, SJR: 3.043, CiteScore: 6)
Advances in Carbohydrate Chemistry and Biochemistry     Full-text available via subscription   (Followers: 9, SJR: 1.453, CiteScore: 2)
Advances in Catalysis     Full-text available via subscription   (Followers: 5, SJR: 1.992, CiteScore: 5)
Advances in Cell Aging and Gerontology     Full-text available via subscription   (Followers: 5)
Advances in Cellular and Molecular Biology of Membranes and Organelles     Full-text available via subscription   (Followers: 14)
Advances in Chemical Engineering     Full-text available via subscription   (Followers: 29, SJR: 0.156, CiteScore: 1)
Advances in Child Development and Behavior     Full-text available via subscription   (Followers: 11, SJR: 0.713, CiteScore: 1)
Advances in Chronic Kidney Disease     Full-text available via subscription   (Followers: 11, SJR: 1.316, CiteScore: 2)
Advances in Clinical Chemistry     Full-text available via subscription   (Followers: 27, SJR: 1.562, CiteScore: 3)
Advances in Clinical Radiology     Full-text available via subscription   (Followers: 1)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 21, SJR: 1.977, CiteScore: 8)
Advances in Computers     Full-text available via subscription   (Followers: 14, SJR: 0.205, CiteScore: 1)
Advances in Cosmetic Surgery     Full-text available via subscription   (Followers: 1)
Advances in Dermatology     Full-text available via subscription   (Followers: 16)
Advances in Developmental Biology     Full-text available via subscription   (Followers: 14)
Advances in Digestive Medicine     Open Access   (Followers: 14)
Advances in DNA Sequence-Specific Agents     Full-text available via subscription   (Followers: 7)
Advances in Drug Research     Full-text available via subscription   (Followers: 26)
Advances in Ecological Research     Full-text available via subscription   (Followers: 44, SJR: 2.524, CiteScore: 4)
Advances in Engineering Software     Hybrid Journal   (Followers: 30, SJR: 1.159, CiteScore: 4)
Advances in Experimental Biology     Full-text available via subscription   (Followers: 9)
Advances in Experimental Social Psychology     Full-text available via subscription   (Followers: 51, SJR: 5.39, CiteScore: 8)
Advances in Exploration Geophysics     Full-text available via subscription   (Followers: 2)
Advances in Family Practice Nursing     Full-text available via subscription   (Followers: 1)
Advances in Fluorine Science     Full-text available via subscription   (Followers: 9)
Advances in Food and Nutrition Research     Full-text available via subscription   (Followers: 69, SJR: 0.591, CiteScore: 2)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 17)
Advances in Genetics     Full-text available via subscription   (Followers: 21, SJR: 1.354, CiteScore: 4)
Advances in Genome Biology     Full-text available via subscription   (Followers: 11, SJR: 12.74, CiteScore: 13)
Advances in Geophysics     Full-text available via subscription   (Followers: 8, SJR: 1.193, CiteScore: 3)
Advances in Heat Transfer     Full-text available via subscription   (Followers: 26, SJR: 0.368, CiteScore: 1)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 11, SJR: 0.749, CiteScore: 3)
Advances in Human Factors/Ergonomics     Full-text available via subscription   (Followers: 26)
Advances in Imaging and Electron Physics     Full-text available via subscription   (Followers: 4, SJR: 0.193, CiteScore: 0)
Advances in Immunology     Full-text available via subscription   (Followers: 37, SJR: 4.433, CiteScore: 6)
Advances in Inorganic Chemistry     Full-text available via subscription   (Followers: 10, SJR: 1.163, CiteScore: 2)
Advances in Insect Physiology     Full-text available via subscription   (Followers: 2, SJR: 1.938, CiteScore: 3)
Advances in Integrative Medicine     Hybrid Journal   (Followers: 6, SJR: 0.176, CiteScore: 0)
Advances in Intl. Accounting     Full-text available via subscription   (Followers: 3)
Advances in Life Course Research     Hybrid Journal   (Followers: 10, SJR: 0.682, CiteScore: 2)
Advances in Lipobiology     Full-text available via subscription   (Followers: 1)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 8)
Advances in Marine Biology     Full-text available via subscription   (Followers: 21, SJR: 0.88, CiteScore: 2)
Advances in Mathematics     Full-text available via subscription   (Followers: 17, SJR: 3.027, CiteScore: 2)
Advances in Medical Sciences     Hybrid Journal   (Followers: 9, SJR: 0.694, CiteScore: 2)
Advances in Medicinal Chemistry     Full-text available via subscription   (Followers: 6)
Advances in Microbial Physiology     Full-text available via subscription   (Followers: 5, SJR: 1.158, CiteScore: 3)
Advances in Molecular and Cell Biology     Full-text available via subscription   (Followers: 26)
Advances in Molecular and Cellular Endocrinology     Full-text available via subscription   (Followers: 8)
Advances in Molecular Pathology     Hybrid Journal   (Followers: 1)
Advances in Molecular Toxicology     Full-text available via subscription   (Followers: 7, SJR: 0.182, CiteScore: 0)
Advances in Nanoporous Materials     Full-text available via subscription   (Followers: 5)
Advances in Oncobiology     Full-text available via subscription   (Followers: 2)
Advances in Ophthalmology and Optometry     Full-text available via subscription   (Followers: 1)
Advances in Organ Biology     Full-text available via subscription   (Followers: 2)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 18, SJR: 1.875, CiteScore: 4)
Advances in Parallel Computing     Full-text available via subscription   (Followers: 7, SJR: 0.174, CiteScore: 0)
Advances in Parasitology     Full-text available via subscription   (Followers: 6, SJR: 1.579, CiteScore: 4)
Advances in Pediatrics     Full-text available via subscription   (Followers: 27, SJR: 0.461, CiteScore: 1)
Advances in Pharmaceutical Sciences     Full-text available via subscription   (Followers: 19)
Advances in Pharmacology     Full-text available via subscription   (Followers: 17, SJR: 1.536, CiteScore: 3)
Advances in Physical Organic Chemistry     Full-text available via subscription   (Followers: 10, SJR: 0.574, CiteScore: 1)
Advances in Phytomedicine     Full-text available via subscription  
Advances in Planar Lipid Bilayers and Liposomes     Full-text available via subscription   (Followers: 3, SJR: 0.109, CiteScore: 1)
Advances in Plant Biochemistry and Molecular Biology     Full-text available via subscription   (Followers: 10)
Advances in Plant Pathology     Full-text available via subscription   (Followers: 6)
Advances in Porous Media     Full-text available via subscription   (Followers: 5)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 19)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 20, SJR: 0.791, CiteScore: 2)
Advances in Psychology     Full-text available via subscription   (Followers: 69)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 7, SJR: 0.371, CiteScore: 1)
Advances in Radiation Oncology     Open Access   (Followers: 3, SJR: 0.263, CiteScore: 1)
Advances in Small Animal Medicine and Surgery     Hybrid Journal   (Followers: 3, SJR: 0.101, CiteScore: 0)
Advances in Space Biology and Medicine     Full-text available via subscription   (Followers: 7)
Advances in Space Research     Full-text available via subscription   (Followers: 434, SJR: 0.569, CiteScore: 2)
Advances in Structural Biology     Full-text available via subscription   (Followers: 6)
Advances in Surgery     Full-text available via subscription   (Followers: 13, SJR: 0.555, CiteScore: 2)
Advances in the Study of Behavior     Full-text available via subscription   (Followers: 36, SJR: 2.208, CiteScore: 4)
Advances in Veterinary Medicine     Full-text available via subscription   (Followers: 20)
Advances in Veterinary Science and Comparative Medicine     Full-text available via subscription   (Followers: 15)
Advances in Virus Research     Full-text available via subscription   (Followers: 6, SJR: 2.262, CiteScore: 5)
Advances in Water Resources     Hybrid Journal   (Followers: 57, SJR: 1.551, CiteScore: 3)
Aeolian Research     Hybrid Journal   (Followers: 6, SJR: 1.117, CiteScore: 3)
Aerospace Science and Technology     Hybrid Journal   (Followers: 398, SJR: 0.796, CiteScore: 3)
AEU - Intl. J. of Electronics and Communications     Hybrid Journal   (Followers: 8, SJR: 0.42, CiteScore: 2)
African J. of Emergency Medicine     Open Access   (Followers: 6, SJR: 0.296, CiteScore: 0)
Ageing Research Reviews     Hybrid Journal   (Followers: 12, SJR: 3.671, CiteScore: 9)
Aggression and Violent Behavior     Hybrid Journal   (Followers: 485, SJR: 1.238, CiteScore: 3)
Agri Gene     Hybrid Journal   (Followers: 1, SJR: 0.13, CiteScore: 0)
Agricultural and Forest Meteorology     Hybrid Journal   (Followers: 18, SJR: 1.818, CiteScore: 5)
Agricultural Systems     Hybrid Journal   (Followers: 32, SJR: 1.156, CiteScore: 4)
Agricultural Water Management     Hybrid Journal   (Followers: 47, SJR: 1.272, CiteScore: 3)
Agriculture and Agricultural Science Procedia     Open Access   (Followers: 4)
Agriculture and Natural Resources     Open Access   (Followers: 3)
Agriculture, Ecosystems & Environment     Hybrid Journal   (Followers: 58, SJR: 1.747, CiteScore: 4)
Ain Shams Engineering J.     Open Access   (Followers: 5, SJR: 0.589, CiteScore: 3)
Air Medical J.     Hybrid Journal   (Followers: 8, SJR: 0.26, CiteScore: 0)
AKCE Intl. J. of Graphs and Combinatorics     Open Access   (SJR: 0.19, CiteScore: 0)
Alcohol     Hybrid Journal   (Followers: 12, SJR: 1.153, CiteScore: 3)
Alcoholism and Drug Addiction     Open Access   (Followers: 12)
Alergologia Polska : Polish J. of Allergology     Full-text available via subscription   (Followers: 1)
Alexandria Engineering J.     Open Access   (Followers: 2, SJR: 0.604, CiteScore: 3)
Alexandria J. of Medicine     Open Access   (Followers: 1, SJR: 0.191, CiteScore: 1)
Algal Research     Partially Free   (Followers: 11, SJR: 1.142, CiteScore: 4)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 2)
Allergologia et Immunopathologia     Full-text available via subscription   (Followers: 1, SJR: 0.504, CiteScore: 1)
Allergology Intl.     Open Access   (Followers: 5, SJR: 1.148, CiteScore: 2)
Alpha Omegan     Full-text available via subscription   (SJR: 3.521, CiteScore: 6)
ALTER - European J. of Disability Research / Revue Européenne de Recherche sur le Handicap     Full-text available via subscription   (Followers: 11, SJR: 0.201, CiteScore: 1)
Alzheimer's & Dementia     Hybrid Journal   (Followers: 56, SJR: 4.66, CiteScore: 10)
Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring     Open Access   (Followers: 6, SJR: 1.796, CiteScore: 4)
Alzheimer's & Dementia: Translational Research & Clinical Interventions     Open Access   (Followers: 6, SJR: 1.108, CiteScore: 3)
Ambulatory Pediatrics     Hybrid Journal   (Followers: 5)
American Heart J.     Hybrid Journal   (Followers: 59, SJR: 3.267, CiteScore: 4)
American J. of Cardiology     Hybrid Journal   (Followers: 67, SJR: 1.93, CiteScore: 3)
American J. of Emergency Medicine     Hybrid Journal   (Followers: 48, SJR: 0.604, CiteScore: 1)
American J. of Geriatric Pharmacotherapy     Full-text available via subscription   (Followers: 13)
American J. of Geriatric Psychiatry     Hybrid Journal   (Followers: 17, SJR: 1.524, CiteScore: 3)
American J. of Human Genetics     Hybrid Journal   (Followers: 40, SJR: 7.45, CiteScore: 8)
American J. of Infection Control     Hybrid Journal   (Followers: 35, SJR: 1.062, CiteScore: 2)
American J. of Kidney Diseases     Hybrid Journal   (Followers: 37, SJR: 2.973, CiteScore: 4)
American J. of Medicine     Hybrid Journal   (Followers: 51)
American J. of Medicine Supplements     Full-text available via subscription   (Followers: 3, SJR: 1.967, CiteScore: 2)
American J. of Obstetrics & Gynecology MFM     Hybrid Journal   (Followers: 1)
American J. of Obstetrics and Gynecology     Hybrid Journal   (Followers: 275, SJR: 2.7, CiteScore: 4)
American J. of Ophthalmology     Hybrid Journal   (Followers: 67, SJR: 3.184, CiteScore: 4)
American J. of Ophthalmology Case Reports     Open Access   (Followers: 5, SJR: 0.265, CiteScore: 0)
American J. of Orthodontics and Dentofacial Orthopedics     Full-text available via subscription   (Followers: 6, SJR: 1.289, CiteScore: 1)
American J. of Otolaryngology     Hybrid Journal   (Followers: 25, SJR: 0.59, CiteScore: 1)
American J. of Pathology     Hybrid Journal   (Followers: 32, SJR: 2.139, CiteScore: 4)
American J. of Preventive Medicine     Hybrid Journal   (Followers: 29, SJR: 2.164, CiteScore: 4)
American J. of Surgery     Hybrid Journal   (Followers: 39, SJR: 1.141, CiteScore: 2)
American J. of the Medical Sciences     Hybrid Journal   (Followers: 12, SJR: 0.767, CiteScore: 1)
Ampersand : An Intl. J. of General and Applied Linguistics     Open Access   (Followers: 7)
Anaerobe     Hybrid Journal   (Followers: 4, SJR: 1.144, CiteScore: 3)
Anaesthesia & Intensive Care Medicine     Full-text available via subscription   (Followers: 67, SJR: 0.138, CiteScore: 0)
Anaesthesia Critical Care & Pain Medicine     Full-text available via subscription   (Followers: 26, SJR: 0.411, CiteScore: 1)
Anales de Cirugia Vascular     Full-text available via subscription   (Followers: 1)
Anales de Pediatría     Full-text available via subscription   (Followers: 3, SJR: 0.277, CiteScore: 0)
Anales de Pediatría (English Edition)     Full-text available via subscription  
Anales de Pediatría Continuada     Full-text available via subscription  
Analytic Methods in Accident Research     Hybrid Journal   (Followers: 6, SJR: 4.849, CiteScore: 10)
Analytica Chimica Acta     Hybrid Journal   (Followers: 44, SJR: 1.512, CiteScore: 5)
Analytica Chimica Acta : X     Open Access  
Analytical Biochemistry     Hybrid Journal   (Followers: 224, SJR: 0.633, CiteScore: 2)
Analytical Chemistry Research     Open Access   (Followers: 13, SJR: 0.411, CiteScore: 2)
Analytical Spectroscopy Library     Full-text available via subscription   (Followers: 14)
Anesthésie & Réanimation     Full-text available via subscription   (Followers: 2)
Anesthesiology Clinics     Full-text available via subscription   (Followers: 25, SJR: 0.683, CiteScore: 2)

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Similar Journals
Journal Cover
International Journal of Adhesion and Adhesives
Journal Prestige (SJR): 0.926
Citation Impact (citeScore): 2
Number of Followers: 20  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0143-7496 - ISSN (Online) 0143-7496
Published by Elsevier Homepage  [3206 journals]
  • Design and fabrication of PVAc-based inverted core/shell (ICS) structured
           adhesives for improved water-resistant wood bonding performance: II.
           Influence of copolymerizing-grafting sequential reaction
    • Abstract: Publication date: Available online 14 February 2020Source: International Journal of Adhesion and AdhesivesAuthor(s): Xiao ZHANG, Long BAI, Jiaxing SUN, Zhiguo LI, Zhao JIA, Jiyou GU PVAc-based inverted core/shell (ICS) structured latex adhesive with improved water- and heat-resistance was prepared by a copolymerizing-grafting sequential reaction approach. The sequential reaction process combines the function of a copolymer layer and an active grafting site to controllably achieve the thermodynamic non-equilibrium ICS morphology with hydrophilic poly(vinyl acetate) (PVAc) cores and hydrophobic polystyrene (PS) shells. The difference between the sequential reaction approach and the chemical grafting method was explored. Structured latex particle morphology, transferring from strawberry-like particles, over particles with large and irregular PS protuberances, to nearly spherical particles with a smooth surface, was microscopically visualized by changing the amount of butyl acrylate (BA) in the PVAc copolymer cores. The heat- and water-resistant bonding of PVAc-based adhesives on wood blocks were evaluated by shear strength at both dry and wet conditions, as well as the boiling water failure time. The results showed that a significant improvement of water- and heat-resistance, especially for boiling water resistance, was successfully obtained. This novel approach paves a way for controlled design and manufacture of high-performance emulsion adhesives through tailoring particle morphology.
       
  • Mineral precipitation, polymerization properties and bonding performance
           of universal dental adhesives doped with polyhedral oligomeric
           silsesquioxanes
    • Abstract: Publication date: Available online 14 February 2020Source: International Journal of Adhesion and AdhesivesAuthor(s): Marta Rizk, Andreas Pohle, Phoebe Dieckmann, Tobias T. Tauböck, Ralf Biehl, Annette Wiegand ObjectivesTo investigate the effect of methacrylate polyhedral oligomeric silsesquioxane (POSS-8) particles on the polymerization process, dentin bond strength, and mineral precipitation of universal dental adhesives.MethodsFive universal adhesives (Adhese Universal, CLEARFIL Universal Bond, Futurabond U, iBOND Universal, Scotchbond Universal) were filled with POSS-8 particles (10 wt%, additionally 2 wt% and 5 wt% in Scotchbond Universal). The particle size and dispersion in ethanol and acetone were examined by dynamic light scattering. Degree of conversion, linear shrinkage, and shear bond strength to dentin treated with the filled and pure adhesives (controls) were measured. Growth of calcium phosphate (Ca/P) precipitates on the adhesive specimens immersed in artificial saliva for up to 28 days was analyzed by energy-dispersive X-ray spectroscopy and scanning electron microscopy. Statistical analyses were performed using ANOVA and Tukey's post-hoc tests (p < 0.05).ResultsThe hydrodynamic radius of the particles in acetone (1.4 ± 0.4 nm) and ethanol (1.1 ± 0.4 nm) revealed their good dispersion. POSS-8 did not change the degree of conversion and dentin bond strength of any adhesive. Ca/P precipitates formed on iBOND Universal specimens doped with POSS-8 after 4 weeks of immersion, but were not detected on the unfilled adhesive. The mineral precipitation of all other adhesives was not improved by POSS-8.SignificancePOSS-8 particles did not compromise polymerization and bonding of universal adhesives. Ca/P precipitation was stimulated by POSS-8 only in iBOND Universal.
       
  • In Vitro Evaluation of Skin Adhesives during Perspiration
    • Abstract: Publication date: Available online 14 February 2020Source: International Journal of Adhesion and AdhesivesAuthor(s): Johannes Eiler, Daniel Hansen, Bahar Bingöl, Kristoffer Hansen, Jason Heikenfeld, Esben Thormann To bridge the gap between current in vitro and in vivo testing, we present the use of a perspiration simulator to evaluate the performance of skin adhesives during sweating. The perspiration simulator mimics human skin in key aspects such as roughness, water contact angle, sweat pore size, sweat pore density, and can be operated at different perspiration rates. In contrast to in vivo testing, a well-defined experimental setup with minimal variation is therefore successfully achieved. To demonstrate the capabilities of the reported perspiration simulator, two model adhesives with different water absorption capabilities are assessed. The peel forces as a function of time are thereby measured during perspiration of a 0.154 M NaCl solution. The peel force decreases immediately when the perspiration rate exceeds the water uptake as determined by an immersion test. However, when the water absorption capabilities are sufficiently high, a delay in the decrease in peel force is observed. Through the use of a fluorescent dye, we can further correlate the loss of adhesion with a spreading of liquid at the skin-adhesive interface.Graphical abstractImage 1
       
  • Orthodontic resin containing bioactive glass: Preparation, physicochemical
           characterization, antimicrobial activity, bioactivity and bonding to
           enamel
    • Abstract: Publication date: Available online 14 February 2020Source: International Journal of Adhesion and AdhesivesAuthor(s): Mariana Almeida Mello Proença, Edilausson Moreno Carvalho, Allana Silva e Silva, Geyse Adriana Corrêa Ribeiro, Paulo Vitor Campos Ferreira, Ceci Nunes Carvalho, José BauerABSTRACTObjectivesTo synthesize experimental orthodontic resins used for bracket bonding containing different concentrations of niobophosphate (NbG) and 45S5 glasses.MethodsExperimental resins (Bis-GMA+UDMA+DMAEMA) were developed with two bioactive glasses (NbG and 45S5) in concentrations of 5, 10 and 20 (wt%). An experimental resin without glass and a commercial resin (Transbond XT) were used. Control of pH and ions release (calcium and phosphate) at different pH values (4 and 7) were evaluated in the time intervals of 24h, 7d, 14d and 28d. Microhardness, bioactivity (SEM, FTIR/ATR) and antibacterial activity of the resins were analyzed. Metal brackets were bonded to premolars (n=10) with the resins to evaluate shear bond strength (SBS).ResultsThe experimental resins containing 45S5 were capable of raising the pH of the solution and showed high values of calcium and phosphate ions release. Resins containing NbG had a neutralizing potential. The NbG and Transbond resins released only phosphate ions. Transbond XT showed high microhardness values when compared with the experimental 45S5 resins (p0,05). The resins with presence of bioactive particles showed antibacterial activity.ConclusionWithout compromising the shear bond strength, bioactive glasses showed the capacity to elevate pH, reduce the hardness of experimental resins when compared with Transbond XT and no filler experimental resin.
       
  • On the influence of mechanical loadings on the porosities of structural
           epoxy adhesives joints by means of in-situ X-ray microtomography
    • Abstract: Publication date: Available online 12 February 2020Source: International Journal of Adhesion and AdhesivesAuthor(s): V. Dumont, C. Badulescu, G. Stamoulis, J. Adrien, E. Maire, A. Lefèvre, D. Thévenet Structural bonding is a beneficial technique extensively used in numerous industrial fields. This technique is however prone to structural defects such as pores, which are created during the mixing of the adhesive and during the shaping of the joint. Depending on their characteristics, these pores are likely to influence the mechanical behaviour of adhesively bonded joints, as they induce local decreases in the cross-section of the bonds and they may also create threatening stress concentrations. It is also fair to assume that the characteristics of the pores within an adhesive joint are subject to changes when the assemblies are submitted to external loads. In order to investigate these changes, adhesively bonded samples were made using two different bicomponent epoxy structural adhesives. These samples were placed inside an X-ray tomograph, containing a tensile machine. In-situ X-ray tomography measurements were made simultaneously with the application of a tensile load on the samples. It was therefore possible to characterise the porosity states of each sample under mechanical loading, and to compute various quantities (porosity volumetric ratio, the pores number, equivalent diameters distributions, etc.). It was found that the pores in the joints are impacted by the increasing mechanical stress, resulting in pore nucleation, pore growth and coalescence. Moreover, the present study shows that this microstructural behaviour cannot be generalised, as different adhesives may display different properties.
       
  • Surface functionalization of AUTOMATED fiber placement manufactured
           composites by atmospheric pressure plasma jet
    • Abstract: Publication date: Available online 12 February 2020Source: International Journal of Adhesion and AdhesivesAuthor(s): Ibrahim Sarikaya, Malik Tahiyat, Ramy Harik, Tanvir Farouk, John Connell This work is part of the National Aeronautics and Space Administration’s (NASA) Advanced Composite Project (ACP) focused on reducing the timeline to certification and directly follows guidelines provided by the Federal Aviation Administration (FAA, Advisory Circular 20-107B, 2010) on improved process controls for adhesively bonded airframe structures. High performance airframe composite structures require reliable fabrication and high fidelity bonding for assembled components. However, a low inherent surface energy and happenstance of surface contamination in multiple manufacturing steps, both contribute to poor adhesive properties in composite materials. Proper surface preparation of pre-bond composite surfaces is, therefore, an active research topic focused on improving fidelity of adhesive bonding. This work discusses application of air driven atmospheric pressure plasma discharge device to mitigate detrimental effects of contaminants on adhesive bonds between carbon fiber composite surfaces. The experimental results indicate that contaminated surfaces treated with APPJ exhibited higher adhesive retention, resulting in higher fracture toughness in double cantilever beam tests.
       
  • Interfacial Bond Behaviour between Hybrid Carbon/Basalt Fibre Composites
           and Concrete under Dynamic Loading
    • Abstract: Publication date: Available online 12 February 2020Source: International Journal of Adhesion and AdhesivesAuthor(s): Cheng Yuan, Wensu Chen, Thong M. Pham, Hong Hao, Cui Jian, Yanchao Shi An experimental investigation on the dynamic interfacial bond behaviours between hybrid carbon/basalt fibre reinforced polymer (FRP) sheets and concrete under high loading velocities (i.e., 8.33E-6, 1.0, 3.0, and 8.0 m/s) is carried out in this study. The single-lap shear specimens are evaluated with different stacking sequences of FRP sheets (i.e., CFRP and BFRP) bonded to the concrete substrates. Experimental results including debonding failure modes, ultimate debonding strain, debonding load, interfacial fracture energy, and bond-slip response are discussed and evaluated. The testing results show that the interfacial bond behaviours between either sole FRP sheet or hybrid carbon/basalt FRP composite and concrete are sensitive to strain rate. The sole FRP sheet exhibits higher strain rate sensitivity than hybrid composite. The interfacial shear resistance between hybrid FRP sheets and concrete is improved due to the effect of FRP hybridization and strain rate. Additionally, the stacking sequence of FRP composites results in different bond performance when the loading speed is less than 1 m/s, while the effect of stacking sequence on bonding behaviour is insignificant when the loading speed is over 1 m/s. The hybrid composites have a relatively longer effective bond length under both quasi-static and dynamic loadings. Empirical formulae are proposed based on the test data to predict the dynamic interfacial bonding strength and shear stress between single or hybrid FRP sheet and concrete at various strain rates.
       
  • Experimental Analysis of Tensile and Compressive Failure Load in
           Single-Lap Adhesive Joint of Green Composites
    • Abstract: Publication date: Available online 6 February 2020Source: International Journal of Adhesion and AdhesivesAuthor(s): Mridusmita Roy Choudhury, Kishore Debnath In this study, the tensile and compressive performance of adhesively bonded single-lap joint of green composites (bamboo fiber/Polylactic acid (PLA)) has been experimentally investigated. The green composites have been fabricated by film stacking method in compression molding. The important factors affecting the performance of the adhesively bonded joint such as overlapping length of the specimen (20, 40, and 60 mm) and width of the specimen (20, 26, and 32 mm) have been studied for epoxy, polyurethane, and parent polymer (PLA) used as bonding materials for joining of developed green composites. From the experimental analysis, it has been found that the higher levels of width and overlapping length of the joint specimen offer better tensile and compressive strength of the joint specimen. The failure loads of the joint specimens have been found to be more for epoxy as compared to PLA and polyurethane used for the purpose of joining. The relative significance of the chosen input parameters has also been found by performing analysis of variance (ANOVA). The most significant parameter has been found to be the width of the specimen for tensile failure load and type of bonding material for compressive failure load. The failure mode analysis has revealed that adhesive and cohesive failures are the major mode of failure of the adhesively bonded green composites under tensile and compressive loadings.
       
  • A comprehensive investigation into the structure-property relationship of
           wax and how it influences the properties of hot melt adhesives
    • Abstract: Publication date: Available online 6 February 2020Source: International Journal of Adhesion and AdhesivesAuthor(s): Divann Robertson, Albert van Reenen, Heidi Duveskog A detailed study was conducted on seven different waxes used in hot melt adhesive formulations together with conventional resins and tackifiers, to characterize the waxes and investigate the effects of wax structure and morphology on the thermal behaviour and basic properties of the resultant hot melt adhesive formulations (HMAs). The waxes selected included representatives of each of the following types: Fischer-Tropsch wax (FT), fully refined paraffin wax (FRP), by-product polyethylene wax (BPPE), microcrystalline wax (microwax), alpha-olefin wax (AO), carnauba wax and first intention polyethylene wax (FIPE). Fourier-transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), high temperature size exclusion chromatography (HT-SEC), nuclear magnetic resonance spectroscopy (NMR) and confocal laser scanning microscopy (CLSM) were used as analytical tools to characterize the waxes. Molecular chain architecture as determined by solution 13C NMR highlighted the superior chain linearity of FT wax. Methyl, ethyl and butyl short chain branching were detected in other waxes. Solid-state 13C CP-MAS NMR provided information on the semi-crystalline nature of the waxes. FIPE, AO and Microwax showed significant structural mobility at room temperature as observed by 1H Wideline NMR and was attributed to chain branching and mobile crystalline domains respectively. This was supported by CLSM micrographs. All waxes enhanced crystallinity in both metallocene catalysed polyethylene (mPE) and ethylene-vinyl acetate (EVA) based HMAs. This was confirmed by the characteristic splitting in FTIR bands and increased DSC enthalpies observed for the HMA relative to the neat polymers. Of the formulations containing high melting waxes, FT wax resulted in HMAs with narrower crystallization profiles, an important factor in determining HMA set times. HMA viscosities were found to be dependent on the molecular weight of the wax while the HMA melting temperatures and enthalpies were more dependent on the crystalline morphology of the waxes.
       
  • Shock Absorption of Semi-interpenetrating Network Acrylic
           Pressure-Sensitive Adhesive for Mobile Display Impact Resistance
    • Abstract: Publication date: Available online 6 February 2020Source: International Journal of Adhesion and AdhesivesAuthor(s): Jong-Ho Back, Dooyoung Baek, Ji-Won Park, Hyun-Joong Kim, Joo-Young Jang, Seong-Ju Lee With the development of mobile display shapes from flat to flexible, the conventional glass cover window must be replaced by a film-type window. However, film-type cover windows have low impact resistance owing to their poor shock absorption. Therefore, to realize their application to flexible displays, it is essential to characterize and improve the shock-absorbing characteristics of the display film. In this study, a semi-interpenetrating network (semi-IPN) acrylic pressure-sensitive adhesive (PSA) consisting of a crosslinked network structure with a linear acrylic polymer chain was developed. The influence of the multi-functional monomer content and UV dose on the properties of the semi-IPN PSA was studied. The peel strength of the semi-IPN PSA was higher than 10 N/25 mm, which is generally considered as the PSA standard for mobile displays. With an increase in crosslink density, the storage modulus increased, but the damping factor decreased. To evaluate shock absorption, a falling ball impact tester was used to estimate the shock absorption ratio (ΔF) of the film. The semi-IPN PSA incorporating 30 phr of the multi-functional monomer exhibited higher ΔF (31.2%) than that of a conventional UV-curable PSA film (24.6%). This shows that even with the relatively low damping factor of the semi-IPN PSA, its structure could improve shock absorption. Moreover, we suggested two mechanisms for shock absorption of the semi-IPN PSA, energy dissipation into the PSA layer and extended contact time.
       
  • Degradation mechanism of Acacia mangium tannin in NaOH/urea aqueous
           solution and application of degradation products in phenolic adhesives
    • Abstract: Publication date: Available online 26 January 2020Source: International Journal of Adhesion and AdhesivesAuthor(s): Jian Liu, Liuliu Wang, Jiongjiong Li, Cheng Li, Shifeng Zhang, Qiang Gao, Wei Zhang, Jianzhang Li Tannin-modified phenolic resin has the characteristics of a high molecular weight, high space resistance, high viscosity, and short shelf life. Therefore, it is still very difficult to use concentrated tannins without pretreatment. To utilize the benefits of condensed tannins, the depolymerization of condensed tannins was carried out in a mixed aqueous solution of sodium hydroxide and urea. The effects of different NaOH/urea ratios on depolymerization were investigated. It was found that tannin treatment was optimized when NaOH/urea/water = 12:7:81 (0.2 mol:0.175 mol:4.5 mol). Gel permeation chromatography (GPC) showed that the weight-average molecular weight of the condensed tannins decreased from 1725 Da and 704 Da to 1523 Da and 327 Da. The changes in the molecular structure of the depolymerized products were detected by MALDI-TOF-MS, 13C nuclear magnetic resonance, and infrared spectroscopy. The results showed that the average degree of polymerization of tannin decreased from 7 to 2. The decrease in the degree of polymerization was mainly due to the breaking of C-4 and C-8 chemical bonds. Some ether bonds were broken, which reduced the molecular weight of the tannin and gave it a more uniform distribution in water. In addition, tannin-modified phenolic resin (DTPF) was prepared by the copolycondensation of phenol, tannin depolymerization products, and formaldehyde under alkaline conditions. The molecular structure and properties of DTPF were studied by 13C-NMR, FTIR, DSC, and TG. The results revealed that, compared with untreated tannin-modified phenolic resin (TPF), DTPF resin had lower formaldehyde emission (0.19 mg/L), better thermal stability, and higher bonding strength (1.19 MPa), according to GB/T 17657-2013. It is important to note that this inexpensive and environmentally friendly catalyst can be used as a raw material for the synthesis process; the degradation products do not need to be recovered and purified, thus avoiding the dehydration and purification of the waste liquor, which is safer for the environment.Graphical abstractImage 1
       
  • Experimental and numerical study of polyethylene hybrid joints: Friction
           stir spot welded joints reinforced with adhesive
    • Abstract: Publication date: Available online 25 January 2020Source: International Journal of Adhesion and AdhesivesAuthor(s): M.R. Adibeig, Gh. Marami, M.A. Saeimi-Sadigh, L.F.M. da Silva Nowadays, the friction stir spot welding method is known as a successful method of joining polymers. Therefore, many efforts are developed to improve the mechanical characteristics of the joints subjected to tensile loading. The aim of this article is to introduce a hybrid system of joining polyethylene plates which involves friction stir spot welding and adhesive bonding. This method is adopted to reduce stress gradients around the weld zone which increases the load carrying capacity of the joint. Taguchi design of experiment was employed and the effects of friction stir spot welding (FSSW) parameters e.g. tool rotational speed, dwell time and plunge rate on the joint strength were investigated. Then, the effects of applying an adhesive were studied. Also, a numerical simulation was conducted to interpret the results. The results show that the dwell time has a more significant effect than the other two parameters. Additionally, it was observed that applying the adhesive remarkably increases the joints strength. This is achieved by reducing the stress gradients in the weld zone.
       
  • Atmospheric air plasma jet for improvement of paint adhesion to aluminium
           surface in industrial applications
    • Abstract: Publication date: Available online 24 January 2020Source: International Journal of Adhesion and AdhesivesAuthor(s): A. Maroofi, N. Navab Safa, H. Ghomi Improvement of paint adhesion to aluminium surfaces is one of the main challenges in many industrial applications. In this paper, we introduce the atmospheric pressure air plasma jet as an appropriate candidate for preparation of 5052 aluminium surface alloy to improve paint adhesion in the industrial level. The employed plasma jet can promote paint adhesion to aluminium surface at the treatment velocity of 2m/min and plasma size of 10mm. Based on the cross-cut test, adhesion of polyurethane paint to the surface greatly increases from 1B to 5B level due to the plasma treatment. According to the results, the surface wettability increases under the influence of the plasma treatment so that water droplet contact angle reduces from 79.0°±2.0° to 27.5°±2.0° after the treatment. Dyne test ink also denotes the increment of surface energy to the greater than 72 mN/m. Besides, we employ various analytical methods to investigate the physical and chemical changes arise from the plasma processing to the surface. Atomic force microscopy (AFM) results show a twofold increase in the roughness parameters of plasma treated surface which can result in a stronger paint and surface interlocking. Chemical analysis of the surface reveals that plasma treatment of the aluminium surface leads to the surface cleaning and formation of hydrophilic functional groups that attract much more water towards the surface and improves the paint adhesion.
       
  • Adhesive strength evaluation for three-dimensional butt joint in terms of
           the intensity of singular stress field on the interface outer edge
    • Abstract: Publication date: Available online 24 January 2020Source: International Journal of Adhesion and AdhesivesAuthor(s): Fei Ren, Nao-Aki Noda Our previous studies analyzed the adhesive strength of butt joint systematically in terms of the intensity of singular stress field (ISSF) by using two-dimensional modeling. In consideration of the actual specimen geometry, in this paper, the adhesive strength of butt joint is analyzed by using three-dimensional modeling. A mesh-independent numerical method combined with the finite element method (FEM) is used to calculate the ISSF. The ISSF distribution on the interface outer edge is analyzed, the effect of adhesive thickness is investigated. The ISSF at the interface vertex is analyzed by using a small fillet instead. The difference between 2D and 3D models for adhesive strength evaluation is discussed. The usability of 2D modeling is investigated.
       
  • Reusability of decal substrates for the fabrication of catalyst coated
           membranes
    • Abstract: Publication date: Available online 1 November 2019Source: International Journal of Adhesion and AdhesivesAuthor(s): A. Stähler, M. Stähler, F. Scheepers, M. Carmo, D. Stolten The use of decal substrates to produce catalyst coated membranes (CCMs) for polymer electrolyte membrane water electrolyzers or fuel cells is a common procedure. For economic and ecological reasons, the reuse of decal substrates would be desirable. Thus far, it has not been investigated whether reuse is possible. Therefore, this study focuses on the repeated coating and transfer in decal processes and investigates changes in substrate properties. After coating Kapton and PTFE with a Carbon-Nafion dispersion, the dry layer was transferred onto a Nafion membrane. This procedure was repeated 50 times. The change in substrate thickness and surface free energy (SFE), as well as the transfer rate (TR), were monitored. The residues on the substrate and scattering of the TR were higher for Kapton compared to PTFE. None of the decal substrates changed its SFE and thickness within the measurement uncertainties. Because of the smaller scattering in the TR, PTFE is more suitable for reuse.
       
  • Experimental and finite element analysis of push-out shear test for
           adhesive joints between pultruded GFRP and Concrete
    • Abstract: Publication date: Available online 23 January 2020Source: International Journal of Adhesion and AdhesivesAuthor(s): A.L.A.C.H.E.K. Ibrahim, R.E.B.O.U.L. Nadège, J.U.R.K.I.E.W.I.E.Z. Bruno Adhesively bonded joints have expanded widely in recent years as more and more advanced glass fibre reinforced materials are being utilized in the civil engineering applications. Hybrid pultruded GFRP concrete bonded beams have been proposed as an economical structural solution for building and footbridge applications due to their favourable properties. Evaluation of shear strength for the adhesive joint is considered as the most important parameter for the design of these hybrid beams. However, the absence of standard method for testing GFRP/concrete bonded joints makes the application of this technology in construction work far from being achieved. There is then a need to make more effort to improve design procedure and to understand the behaviour of this assembly. In this context, the present paper aims to characterize the shear test “Push out” in order to provide more information about the influence of the different geometrical parameters on the shear strength of the adhesive joint. For this purpose, experimental and numerical investigations were carried out to investigate the effect of various parameters on the failure load and the failure mode of the specimens such as surfaces treatment, shape of GFRP profile, adherents’ dimensions (width and thickness), adhesive thickness, bonded length and free height. The numerical investigations were performed by three-dimensional (3D) nonlinear Finite Element (FE) model. The constitutive relationship of the pultruded GFRP is modelled by means of a linear orthotropic law, while the concrete behaviour is defined by means of an elastic plastic damage model with a non-local formulation. In order to reduce computing time, interface elements with zero thickness were used to model the adhesive joint with a linear constitutive law. Using this model, stress distributions along the interface were investigated and the effects of different geometrical parameters were discussed.
       
  • Numerical analysis of the strength and interfacial behaviour of adhesively
           bonded joints with varying bondline thicknesses
    • Abstract: Publication date: Available online 23 January 2020Source: International Journal of Adhesion and AdhesivesAuthor(s): Wang Guo, Peijian Chen, Liyuan Yu, Guangjian Peng, Yucheng Zhao, Feng Gao A new model of adhesive joints with varying bondline thicknesses is proposed and explored numerically in this paper. Three types of roughness morphology are considered, including triangular, circular and trapezoidal protuberances. With the help of cohesive zone model and a user subroutine USDFLD code implemented in finite element method, the ultimate load, the fracture energy as well as the interface damage are calculated. The effect of protuberance’s geometric parameters, adhesive type as well as interfacial defect are comprehensively studied. It is found that by introducing protuberances, a gradient change of the adhesive thickness is formed, thus changing the load bearing capacity of adhesive joints. Proper tuning the protuberance’s geometric parameters will effectively improve the strength and interfacial behavior of bonded joints. What is more, defects must be carefully removed in order to use protuberances to improve a SLJs’ strength. The findings should be useful for the design of novel adhesive structures and enlighten new adhesively bonded strategies.
       
  • Reinforced biobased adhesive for eco-friendly sandwich panels
    • Abstract: Publication date: Available online 22 January 2020Source: International Journal of Adhesion and AdhesivesAuthor(s): Pablo Resende Oliveira, Michael May, Tulio Hallak Panzera, Fabrizio Scarpa, Stefan Hiermaier This work describes the development of a bio-polyurethane (bio-PU) adhesive made from castor oil plant to be used in sustainable (eco-friendly) sandwich panels made from recycled plastic waste. Low-cost fillers, such as Portland cement and recycled rubber particles are incorporated into the biopolymer to modify its mechanical behaviour. Epoxy is also used to benchmark the mechanical performance of the reinforced biopolymer described in this work. A full factorial design is performed to identify the effects of the types of adhesive, particles and their weight fraction on the mechanical and physical properties of hybrid panels. Single lap and adapted T-peel tests are used to assess the adhesion of the polymers to the aluminium surfaces. The inclusion of 3 wt% cement particles in the biopolymer provides a significant increase in the tensile strength and stiffness compared to the pristine bio-PU. Other properties that benefit from that amount of reinforcement in the bio-adhesive are the impact resistance and reduction of density and porosity compared to higher fractions of inclusions. Despite its lower mechanical properties, the biopolymer with rubber particles provides however an increase of the single lap shear strength, the opposite of what happens when using the reinforced epoxy polymer. The T-peel test also highlights the higher bonding affinity of the biopolymer to the sustainable sandwich core; that indicates the promise of using this biopolymer-reinforced adhesive in secondary and sustainable applications.
       
  • Investigation of the differences between photochemical and photothermal
           laser ablation on the shear strength of CFRP/CFRP adhesive joints
    • Abstract: Publication date: Available online 20 January 2020Source: International Journal of Adhesion and AdhesivesAuthor(s): Erhan Akman, Yalçın Erdoğan, Mustafa Özgür Bora, Onur Çoban, Belgin Genc Oztoprak, Arif Demir Ensure high bonding strength and durability is very important for composite materials that are widely used by many different industries. In order to achieve this, the surfaces of the composite materials should be prepared for the adhesion process. Surface preparation with laser is a promising technique for the adhesive joint. However, the diversity offered by the advances in laser technologies and the multiplicity of parameters that must be controlled in laser material processing makes the process somewhat complex. In the present study, two different lasers have been used with different wavelengths (355 nm (UV) and 10600 nm (IR)) and pulse durations (4,4 ns and 5 μs), to increase the lap shear strength of the adhesive joint of carbon fiber reinforced polymer (CFRP) materials. While the ultraviolet (UV) laser with high photon energy creates photo-chemical ablation, infrared laser (IR) causes photo-thermal ablation due to their low photon energy. CFRP samples treated with different lasers and the accumulated laser fluences have been adhesively joined and the results evaluated experimentally. According to the results, differences in laser ablation mechanism cause structural differences on CFRP surfaces. While resolidified epoxy was observed on CO2 laser treated surfaces, no residues were detected on UV laser treated surfaces. However, to avoid delamination or fiber damage risks an optimization of laser parameters are recommended to be performed for both laser systems.
       
  • Effect of sodium dodecyl sulfate (SDS) on mechanical performance of
           polyvinyl-acetate-based emulsion polymer isocyanate
    • Abstract: Publication date: April 2020Source: International Journal of Adhesion and Adhesives, Volume 98Author(s): Kefeng Zhang, Hongjiu Hu, Shuang Li, Yaolong He, Jing Guo Aqueous vinyl acetate copolymer latex with addition of sodium dodecyl sulfate (SDS) was crosslinked by polymeric diphenylmethane diisocyanate (pMDI) for preparing the emulsion polymer isocyanate (EPI) as a high-performance wood adhesive. The effect of SDS on the quasi-static tensile response, dynamic mechanical behavior as well as the residual isocyanate group (NCO) in the cured polymer film was thoroughly discussed. Meanwhile, the bonding strength and water resistance of the adhesive were also investigated in detail. The results indicate that the tensile strength, Young's modulus and dynamic storage modulus markedly increased under a dry condition with the increased weight ratio of SDS. Moreover, a suitable loading of SDS would significantly improve the strength and stiffness of cured film at high humidity, resulting in better adhesive properties and water resistance of glue joints. The EPI, modified at 0.25 wt% of SDS, exhibits not only the highest moisture resistance of the cured films, but also the best adhesive properties. Finally, added surfactant is found to efficiently reduce the residual NCO in the polymer film by means of Fourier transform infrared spectroscopy (FTIR). It enhances the EPI in terms of a larger crosslink density, glass transition temperature and relative humidity due to the more effective dispersion and chemical reaction of pMDI in the main component.Graphical abstractImage 1
       
  • Under water glued stud bonding fasteners for offshore structures
    • Abstract: Publication date: April 2020Source: International Journal of Adhesion and Adhesives, Volume 98Author(s): Sebastian Myslicki, Heinrich Kordy, Marvin Kaufmann, Romain Créac'hcadec, Till Vallée The installation of offshore wind turbines has achieved rapid and substantial progress worldwide and further increase is predicted by enhanced technologies that will reduce costs and increase service time. Secondary structures applied to the primary structure, as the transition piece of a monopole, can be e.g. cable support, boat landing or anode systems. These structures are often welded, which leads to problematic notch effects and hydrogen embrittlement, especially for underwater applications. Also the handling of technical equipment as power current or artificial housings for scuba divers for underwater welding is challenging. Adhesive bonding will lead to cost reduction as the mentioned negative aspects can be avoided. The corrosion protection coating and the primary structure will no longer be damaged and therefore do not need a subsequent coating. This article focuses on the area which is permanently exposed to water. A critical point is how the capability to form adhesion and cohesion, will be influenced by the application process under water. Therefore, stud bonding fasteners are designed that enable the injection of adhesive to the bonding area under water. The load capacities for different adhesives, surface pre-treatments and the degradation by exposure to artificial sea water were investigated. Adhesion was achieved with two different adhesives, which were able to cure and realize reasonable strength under water. Furthermore, two selected coating systems were able to improve the performance of the adhesive bond.
       
  • Improvement of curing reaction activity of one-component room
           temperature-curable epoxy adhesive by the addition of functionalized
           graphene oxide
    • Abstract: Publication date: April 2020Source: International Journal of Adhesion and Adhesives, Volume 98Author(s): Baoming Li, Xiaoli Wang, Mengdi Bai, Yu Shen Functionalized graphene oxide (GO) nanocomposites including GO-Fe and GO-Fe-P were prepared and used as a curing additive for a one-component room temperature-curable epoxy adhesive (OCRTCEA). The results showed that the functionalized GO nanocomposites were conducive to accelerating the curing reaction of OCRTCEA with a moisture-activated ketimine as a latent curing agent, and when OCRTCEA containing 1 wt% GO-Fe-P was exposed to air at room temperature for 24 h, its lap shear strength reached 11.2 MPa, which was 144% higher than that of pure OCRTCEA under the same test conditions. Furthermore, the storage stability of OCRTCEA containing 1 wt% GO-Fe-P was similar with that of pure OCRTCEA over 60 days of storage. The enhanced curing reaction activity of OCRTCEA might be due to the role of curing accelerator of GO nanocomposites, the enhanced polarity of OCRTCEA because of the addition of GO nanocomposites, and the special morphology of GO nanocomposites.
       
  • Interfacial adhesion in glass-fiber thermoplastic composites processed
           from acrylic reactive systems, a multi-scale experimental analysis
    • Abstract: Publication date: April 2020Source: International Journal of Adhesion and Adhesives, Volume 98Author(s): Q. Charlier, F. Lortie, J.-F. Gérard Interfacial adhesion in poly (methyl methacrylate) (PMMA)/glass fiber (GF) composites which are processed by in-situ polymerization of an acrylic reactive mixture, has been studied at both micro- and macro-scales. On one hand model systems were evaluated at microscale using the microbond test. On the other the 15° off-axis tensile test was used to assess the fiber/matrix interfacial adhesion at macroscale in real-sized thermoplastic (TP) composite parts. For each test, reference epoxy/GF samples were characterized alongside PMMA/GF composites. Results demonstrate that the fiber/matrix interfacial strength in PMMA/GF reaches 60% and 75% of the epoxy reference value at micro and macroscale, respectively. It proves the consistency of analyses at both scales. Thus, a micromechanical analysis relying on the microbond test appears as a reliable tool to estimate the fiber/matrix interfacial bond strength which is experienced in real-sized parts. Overall results also highlight the interest of manufacturing GF/PMMA composites through a reactive process to yield parts exhibiting strong interfacial properties. It may be promising for the development of thermoplastic solutions for structural composite applications.
       
  • Treating UHMWPE surface for enhancing the adhesion properties by cellulose
           grafting
    • Abstract: Publication date: April 2020Source: International Journal of Adhesion and Adhesives, Volume 98Author(s): Tarek Dayyoub, Aleksey V. Maksimkin, Fedor S. Senatov, Sergey D. Kaloshkin, Anna Zimina, Evgeniy A. Kolesnikov The surface of ultrahigh molecular weight polyethylene (UHMWPE) was grafted by cellulose through using ultraviolet initiation. Benzophenone was used as a coupling agent. The success of cellulose grafting has been proven by Fourier transform infrared spectroscopy. The mechanical analysis of the glued UHMWPE films showed a presence of glue traces on the surface of the UHMWPE films. The best results were obtained after 1 h of mixed acids pre-treatment. An increase of 1400% in the tensile strength of the glued UHMWPE, and a decrease of 10% in the tensile strength of the oriented UHMWPE films were observed. Also, the presence of cellulose on the surface of the modified UHMWPE films were observed in the SEM micrographs. In comparison with the untreated UHMWPE films, contact angle measurements proved that the treated UHMWPE films were still hydrophobic. This approach to UHMWPE surface treatment could be used in preparing a hierarchical structure for some of the UHMWPE forms (for example a hierarchical structure of bulk, porous and UHMWPE films).
       
  • Development of a cornstarch adhesive for laminated veneer lumber bonding
           for use in engineered wood flooring
    • Abstract: Publication date: April 2020Source: International Journal of Adhesion and Adhesives, Volume 98Author(s): Xiong Xian-qing, Yuan Ying-ying, Niu Yi-ting, Zhang Liang-ting To produce aldehyde-free engineered wood flooring, we developed a cornstarch-based adhesive for laminated veneer lumber bonding. Polyvinyl alcohol was used as the tackifier, wheat flour as the filler, and polyisocyanate prepolymer as the reinforcing agent. After the application of the cornstarch adhesive to the engineered wood flooring, we found that the cornstarch adhesive had excellent adhesion in the laminated wood parquet. The properties of the cornstarch-based adhesive met the requirements of GB/T 14074–2006, GB/T 20241–2006, and GB/T 18103–2006 for non-structure interior adhesives. When lumber veneer (thickness, ≤2.2 mm) was used, the engineered wood flooring showed good dimensional stability after 1–2 min of hot-pressing pretreatment (temperature, 100–120 °C; pressure, 0.83 MPa). The main physical and chemical properties also met the requirements of GB/T18103-2000, Engineered Wood Flooring. The emission of formaldehyde during production was ≤0.05 mg/l, lower than the GB/T18103-2000 requirement of ≤0.124 mg/l. The results of this study provide practical and forward-looking guidelines for expanding the application of biomass-based adhesives in the manufacture of laminated veneer lumber.
       
  • Boron nitride inclusions within adhesive joints: Optimization of
           mechanical strength and bonded defects detection
    • Abstract: Publication date: April 2020Source: International Journal of Adhesion and Adhesives, Volume 98Author(s): Matthias Barus, Hélène Welemane, Valérie Nassiet, Marina Fazzini, Jean-Christophe Batsale Non Destructive Testing (NDT) by active InfraRed Thermography (IRT) of bonded Carbon Fibers Reinforced Plastic (CFRP) laminates is a very challenging issue. Adding Boron Nitride (BN) particles within the joint material provides an interesting solution to better capture bonding defects. Though increasing additives leads to the improvement of NDT, the validation of this solution requires the mechanical characterization of the new joint material. In this way, the influence of particles on the mechanical properties of the adhesive joint is first investigated via double strap lap shear tests for different BN volume fraction. At the same time, controlled size void inclusions are generated within composite assemblies in order to evaluate the IRT ability to detect bonded defects inside BN-based adhesives. It is demonstrated that thermal data post-processing methods such as Singular Values Decomposition (SVD) and Principal Component Thermography (PCT) help to get the best trade-off between mechanical performance and defect detection.
       
  • Characterization of adhesive joints under high-speed normal impact: Part I
           – Experimental studies
    • Abstract: Publication date: April 2020Source: International Journal of Adhesion and Adhesives, Volume 98Author(s): Kenneth Gollins, Niell Elvin, Feridun Delale This two-part article presents an experimental method with numerical verification of the characterization of adhesive bonds under normal impact loading. Part I presents experimental results of the mechanical behavior of two different adhesives (a methacrylate and an epoxy). Though the two adhesives have similar static behavior, their impact strengths are significantly different. Thus adhesives that are to be used under impact loading need their own dynamic characterization tests. Here we present an impact test that is analogous to the commonly used blister test for static adhesive testing. One major advantage of the present impact test is that existing apparatus and methods that are currently used for ballistic penetration can be readily adopted for the proposed dynamic test. The average dynamic stress as well as energy absorbed by the adhesive are experimentally determined by the proposed method.
       
  • Corrigendum to “Pre-bond surface inspection using laser-induced
           breakdown spectroscopy for the adhesive bonding of multiple materials”
           [Int. J. Adhes. Adhes. 93(2019) 93–101]
    • Abstract: Publication date: April 2020Source: International Journal of Adhesion and Adhesives, Volume 98Author(s): Tadatake Sato, Kenichi Tashiro, Yoshizo Kawaguchi, Hideki Ohmura, Haruhisa Akiyama
       
  • Laser induced breakdown spectroscopy of polymer matrix composites for
           real-time analysis of trace surface contaminants: A review
    • Abstract: Publication date: April 2020Source: International Journal of Adhesion and Adhesives, Volume 98Author(s): Rodolfo Ledesma, Frank Palmieri, John Connell Laser induced breakdown spectroscopy (LIBS) is a materials characterization technique that has been advanced and refined to provide in situ, real-time quality control of polymer matrix composite (PMC) surfaces. A LIBS system was designed and assembled at the NASA Langley Research Center in order to detect ultralow concentrations of silicone contamination on carbon fiber reinforced polymer (CFRP) materials. The LIBS instrument provides high sensitivity detection and nearly non-destructive inspection of PMC substrates prior to adhesive bonding. This review focuses on work conducted using LIBS as a characterization tool for surface contaminants for improved adhesive bonding and coating processes of CFRP materials. In addition, this work describes how the LIBS technique was advanced by analyzing the laser parameters, studying the laser-matter interactions, and comparing results to X-ray photoelectron spectroscopy. Discussion is also presented on LIBS instrumentation, recommendations for laser parameters and instrumentation components, LIBS technique maturity, applications, and limitations.
       
  • The effect of multi-walled carbon nanotubes on the mechanical behavior of
           basalt fibers metal laminates: An experimental study
    • Abstract: Publication date: April 2020Source: International Journal of Adhesion and Adhesives, Volume 98Author(s): Hamed Aghamohammadi, Reza Eslami-Farsani, Abbas Tcharkhtchi Fiber metal laminates (FMLs) are a group of hybrid composite materials consisting of metal and fiber-reinforced polymer layers. In this study, the effects of multi-walled carbon nanotubes (MWCNTs) on the flexural and high-velocity impact behavior of FMLs made up of aluminum 2024-T3 and basalt fibers/epoxy layers were investigated. The fracture surfaces of samples were analyzed by scanning electron microscopy (SEM). Results showed that the adhesion of composite plies, as well as the interfaces between aluminum and basalt fibers/epoxy layers, were significantly affected by the inclusion of the MWCNTs. The good adhesion of MWCNTs within the body of FMLs caused considerable improvement in the flexural properties. In this regard, the optimal content of MWCNTs was 0.5 wt%, and compared to the samples without MWCNTs, the flexural strength and flexural modulus values improved 36.62% and 60.16%, respectively. However, contrary to the effectiveness of MWCNTs on the flexural performance of samples, the high-velocity impact properties in terms of specific absorbed energy and limit velocity values were affected adversely.
       
  • Enhancing thermal conductivity of epoxy with a binary filler system of
           h-BN platelets and Al2O3 nanoparticles
    • Abstract: Publication date: April 2020Source: International Journal of Adhesion and Adhesives, Volume 98Author(s): Hasan Yetgin, Salih Veziroglu, Oral Cenk Aktas, Tuncay Yalçinkaya Epoxy resin is a common adhesive bonding material used to join dissimilar materials, especially in the electronics and aerospace industries. However, its low thermal conductivity and high coefficient of thermal expansion limit the direct use of epoxy in practical applications. In order to improve thermo-mechanical properties, we have prepared a series of epoxy composites using a binary system of hexagonal-boron nitride (h-BN) and aluminum oxide (Al2O3) fillers and analyzed the effect of the ratio of these fillers on the thermal conductivity of composites. While h-BN platelets form the main thermal conductive network, Al2O3 nanoparticles bridge the separated h-BN platelets to build more thermal conductive pathways. We proposed the improving of thermal conductivity as well as the mechanical properties of the epoxy matrix by incorporating h-BN and Al2O3 fillers at an optimum ratio.
       
  • Characterization of Adhesive Joints Under High-Speed Normal Impact: Part
           II – Numerical Studies
    • Abstract: Publication date: Available online 2 January 2020Source: International Journal of Adhesion and AdhesivesAuthor(s): Kenneth Gollins, Niell Elvin, Feridun Delale This two-part article presents an experimental method with numerical verification of the characterization of adhesive bonds under normal impact loading. Part I presented the experimentally measured performance of static and impact behavior of two adhesives (a methacrylate and an epoxy). Part II presents the numerical modeling of the static and dynamic tests performed in Part I. The finite element simulations are used to determine approximate dynamic material modeling parameters. The simulations are also useful in estimating certain critical performance aspects of the adhesive for the proposed impact test such as the estimation of contact force time histories, the dynamic stress time history profiles within the adhesive, and to the various energy components in the adhesives and adherends.
       
  • Mode II Interlaminar Fracture Toughness of Woven E-glass/Epoxy Composites
           in the Presence of Mat Interleaves
    • Abstract: Publication date: Available online 3 December 2019Source: International Journal of Adhesion and AdhesivesAuthor(s): Mohammad Reza Hosseini, Fathollah Taheri-Behrooz, Mazaher Salamat-talab Composite laminates are widely used as primary load bearing structures in various industries. Using a thin layer of chopped strand mat between sub-laminates of a thick structural composite laminate would prevent crack development across the whole laminate thickness and reduce the risk of catastrophic failure in the structure. In this research, end-notched flexure (ENF) specimens were used to examine the impact of the mat layer between woven layers on the mode II interlaminar fracture toughness of glass/epoxy composites. ENF specimens are fabricated using hand lay-up method assisted by vacuum bagging technique. Experimental results revealed that the existence of a mat interlayer resulted in a reduction of interlaminar fracture toughness of the delamination initiation and propagation by 59% and 35%, respectively, compared to one without mat interlayer. Moreover, results showed that in the ENF specimens without interleaving of the mat, the dominant mechanism of increased fracture toughness is not fiber bridging and delamination propagates in fiber-matrix interface in these specimens.
       
  • Preparation of a one-component epoxy adhesive using PET bottle waste
           derived terephthalic dihydrazide as latent curing agent
    • Abstract: Publication date: Available online 3 December 2019Source: International Journal of Adhesion and AdhesivesAuthor(s): Neena George, T.K. Bindu Sharmila, Thomas Kurian The present work discusses the effect of PET bottle waste derived terephthalic dihydrazide (TDH) as a latent curing agent in diglycidyl ether of bis-phenol A (DGEBA) based epoxy resin. Differential scanning calorimetric studies were conducted to examine the latent character of TDH and its curing pattern in DGEBA and FTIR spectroscopy was used to confirm the completion of curing. A latent accelerator (Ajicure PN-40) was used to reduce the extremely high cure temperature of DGEBA-TDH system to a feasible range. Cure characteristics, barrier and aluminium to aluminium (Al/Al) adhesive properties of the synthesized adhesive with varied TDH content were studied to optimize the dosage of TDH. Pot life of the synthesized adhesive was determined through brookfield viscosity measurements. Ageing studies of the bonded Al/Al samples were carried out to study the practical utility of the newly synthesized adhesive. The properties of TDH cured one-component epoxy adhesive were compared with a commercial dicyandiamide (DICY) cured one-component epoxy adhesive. TDH cured adhesive displayed comparable properties to the DICY cured adhesive.
       
  • High-performance epoxy-based adhesives modified with functionalized
           graphene nanoplatelets and triblock copolymers
    • Abstract: Publication date: Available online 2 December 2019Source: International Journal of Adhesion and AdhesivesAuthor(s): Panta Jojibabu, Y.X. Zhang, Andrew N. Rider, John Wang, Richard Wuhrer, B. Gangadhara Prusty In this study, a high-performance epoxy-based adhesive was developed by adding graphene nanoplatelets (GNPs) and phase-separated triblock copolymers (BCPs) to enhance the lap shear strength of the adhesive joints. The GNPs were functionalized using an ultrasonicated ozonolysis (USO) method so as to achieve a homogeneous and stable dispersion in the epoxy matrix. The USO treated GNPs (OZ-GNPs) were incorporated into epoxy resin at different weight fractions using a 3-roll mill technique. Both poly(methyl methacrylate)-poly(butyl acrylate)-poly(methyl methacrylate) (MAM) and poly(styrene)-poly(butadiene)-poly(methyl methacrylate) (SBM) BCPs were mixed separately as toughening agents. Single lap shear joints were prepared by bonding aluminium sheets using the developed adhesives to study the lap shear strength of the joints. The further improvement in the lap shear strength was observed for the hybrid epoxy system with GNPs and BCP. Adding 1.0 wt.% OZ-GNPs into 10 wt.% SBM modified epoxy adhesive resulted in the lap shear strength increasing by 129%, compared to that of the unmodified epoxy. Raman spectroscopy and scanning electron microscope (SEM) studies found that the USO treatment facilitated the stable dispersions and improved epoxy bonding due to the oxygen functional groups introduced onto the GNP surfaces. Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and thermogravimetric analyzer (TGA) studies showed that the GNPs and BCPs were well bonded with epoxy resin without compromising the thermal stability. To better understand the influence of GNPs and BCPs on the lap shear strength, the fracture surfaces of the joints were studied using SEM. The fracture images showed that the BCPs formed different nanostructures in the epoxy matrix and the resulting nanostructures activated different toughening mechanisms that were responsible for the improvement in the lap shear strength, while the OZ-GNPs increased the joint strength by stiffening the matrix.
       
  • Design and fabrication of PVAc-based inverted core/shell (ICS) structured
           adhesives for improved water-resistant wood bonding performance: I.
           Influence of chemical grafting
    • Abstract: Publication date: Available online 2 December 2019Source: International Journal of Adhesion and AdhesivesAuthor(s): Xiao ZHANG, B.A.I. Long, Jiaxing SUN, Zhiguo LI, Zhao JIA, Jiyou GU Strategy for fabricating inverted core/shell (ICS) structured latex particles to improve the water- and heat-resistance of PVAc-based adhesives was investigated. A grafting layer was fabricated with acrylonitrile (AN) to achieve a thermodynamic non-equilibrium ICS morphology with a hydrophilic poly(vinyl acetate) (PVAc) core and a hydrophobic polystyrene (PS) shell. The function of the grafting layer was explored by tuning the AN loading levels and core-to-shell ratios. Special latex particle morphologies, transferring from strawberry-like with secondary PS particles, over neat strawberry-like, to final ball-like morphology, were observed and verified by electron microcopies. The wood adhesive performance of PVAc-based latex adhesives, particularly for heat- and water-resistant bonding, were evaluated by shear strength at both dry and wet conditions, as well as the boiling water failure time, showing a significant enhancement of boiling water resistance. This general approach opens an avenue for controlled design and manufacture of high-performance emulsion-based adhesives containing structured particles.
       
  • Droplet-Patterning of Viscous Adhesive Assisted with Microfluidic
           Technique
    • Abstract: Publication date: Available online 29 November 2019Source: International Journal of Adhesion and AdhesivesAuthor(s): Zheng Xu, Ping Zhu, Xiaoyu Xu, Wei Zhao, Xiaodong Wang, Junshan Liu, Liding Wang In transfer process of viscous adhesive, the initial geometrical shape of droplet has crucial influence on the filling completeness. Herein a droplet-patterning method assisted with microfluidic technique was presented to control the shape of viscous adhesive, in which three kinds of adhesives were selected as samples, spanning two orders of viscosity magnitude from 83 mPa·s to 7792 mPa·s. Microfluidic technique was developed to obtain the anti-adhesive boundaries of original polygon patterns. Considering viscous dissipation, a criterion was established to confirm the droplet-volume limitation of overflowing across anti-adhesive boundary. Moreover, the capability of droplet-patterning was evaluated with the ratio of droplet-pattern to original polygon and the dynamics of patterning was analyzed. Under the conditions of low Reynolds and Weber numbers, the smaller area and more edges of polygon, lower viscosity and more non-polar groups of adhesive are helpful to improve the patterning capability.
       
  • Effects of glue-line thickness and manufacturing defects on the pull-out
           behavior of glued-in rods
    • Abstract: Publication date: Available online 28 November 2019Source: International Journal of Adhesion and AdhesivesAuthor(s): Bo-Han Xu, Jin-Hua Guo, Abdelhamid Bouchaïr Glued-in rods are offering to timber joints not only enhanced stiffness and high load capacity but also aesthetical appearance and good fire resistance. However, no consistent manufacturing process and quality control method is reported in the literature. It is necessary to estimate the effect of possible manufacturing defects on pull-out behavior of glued-in rods. This paper presents the experimental results on glued-in rods with two types of possible manufacturing defects on site: eccentric position of rod in hole and inclined setting of rod in hole. The effect of manufacturing defects was investigated on the samples with three different glue-line thicknesses. A finite element model considering the elastic behavior of materials with their measured elastic parameters and dimensions is proposed. It illustrates the evolution of the stress distribution in the connection zone and explains the observed brittle failure modes.
       
  • Structural adhesive bonding characterization using guided Lamb waves and
           the vertical modes
    • Abstract: Publication date: April 2020Source: International Journal of Adhesion and Adhesives, Volume 98Author(s): Camille Gauthier, Mounsif Ech-Cherif El-Kettani, Jocelyne Galy, Mihai Predoi, Damien Leduc The aim of this paper is to present a method to evaluate and qualify the adhesion level in a structural metal/adhesive/metal bonding using ultrasonic guided Lamb waves. The samples are manufactured with different surface treatments in order to obtain different levels of adhesion. Using Lamb dispersion modes associated to the Jones rheological model, it is shown that it is possible to evaluate different levels of adhesion. Furthermore, the vertical longitudinal mode VL is particularly focused. Results show that the measurement of its frequency cut-off, which is very simple and fast to achieve, can be a very good indicator on the integrity of the bonding.
       
  • Doxycycline as a dentin pretreatment agent for MMP-2 inhibition and
           maintaining hybrid layer stability over time
    • Abstract: Publication date: Available online 18 November 2019Source: International Journal of Adhesion and AdhesivesAuthor(s): Rodrigo Varella de Carvalho, Elenusa de Souza Oltramari, Emanuela Gaviolli, Alexandra Graunke, Luiz Alexandre Chisini, Ataís Bacchi, Paula Cristine Ghiggi, Françoise Hélène van de Sande The aim of this study was to evaluate the effect of doxycycline (DXC) as a dentin pretreatment agent on the inhibition of matrix metalloproteinase 2 (MMP-2) and preservation of microtensile bond strength (μTBS) of the adhesive-dentin interface over time. MMP-2 was analyzed by gelatin zymography in buffers containing 5 mM CaCl2 (Tris-CaCl2) in 50 mM Tris-HCl buffer with the addition of DXC at 2, 0.2 and 0.02% (v/v). The effect of DXC at 0.2% (concentration defined after MMP-2 inhibition analysis) on the μTBS of the adhesive-dentin interface was evaluated after 24 h and 6 months. Data (MPa) were analyzed by two-way ANOVA followed by pairwise comparison within groups at different time-points of water-storage (24 h and 6 months) (α = 0.05). DXC was able to completely inhibit MMP-2 expression at 2% and 0.2%, whereas at 0.02% there was only a partial inhibition. Dentin pretreatment with DXC at 0.2% was capable of maintaining μTBS values up to 6 months. Under visual inspection, an evident staining of the adhesive interface was observed for DXC. DXC had positive effects on MMP-2 inhibition and μTBS up to 6 months. However, the staining of the adhesive interface with DXC may be expected. Although DXC may improve in vitro bond stability in dentin, the clinical impact of the staining of the adhesive interface should be clarified.
       
  • Nematic liquid crystal 4-Cyano-4'-pentylbiphenyl functionalization of
           MWNTs for improved thermal and mechanical properties of silicone pressure
           sensitive adhesives
    • Abstract: Publication date: Available online 4 November 2019Source: International Journal of Adhesion and AdhesivesAuthor(s): Jinbao Zheng, Yangyang Zong, Gaiqing Zhao, Zhenqiang Yu, Mingliang Wang, Caizhen Zhu, Cuihua Li, Jianhong Liu, Dayong Gui In this research, nanocomposite modified pressure sensitive adhesives (PSA) (5CB-MWNTs/PSA) with high mechanical and thermal properties were fabricated via nematic liquid crystal 4-cyano-4'-pentylbiphenyl (5CB) functionalized multi-walled carbon nanotubes (MWNTs). The results showed that 5CB interacted with MWNTs via non-covalent interactions e.g. π-π stacking, which not only improved the dispersion and orientation of MWNTs in a silicone PSA but also the compatibility between MWNTs and the silicone material. The tensile strength of 5CB-MWNT/PSA was increased to 14.5 MPa while the mass fraction of MWNTs was 1.0%, which was an enhancement of 943% over that of the MWNTs/PSA and 28 times greater than that of the neat PSA. In addition the thermal conductivity of the PSAs filled with the 5CB-MWNTs were improved to 1.28 W/(m•K) at a mass fraction of 10%, which was increased by 552% over that of the neat PSA and 231% over that of the MWNT/PSA. The resulting thermally conductive and mechanically applicable silicone PSA nanocomposites could be significant in a wide variety of pressure sensitive adhesive applications.
       
  • Self-limiting caries excavation with a polymerbur: Adhesive bonding to
           residual dentin
    • Abstract: Publication date: Available online 14 November 2019Source: International Journal of Adhesion and AdhesivesAuthor(s): Teresa Wohlleb, Dalia Kaisarly, Peter Rösch, Karl-Heinz Kunzelmann ObjectivesThe aim of this study was to evaluate the bonding of an universal adhesive to residual affected dentin after polymer bur excavation of natural caries lesions in human teeth.Materials and MethodsCaries excavation with a polymer bur and with a carbide bur were compared. A microtensile bond strength (μ-TBS) test was performed in a split-tooth design (n=20/group). A universal adhesive (Scotchbond Universal, 3M-Deutschland, Neuss/Germany) was applied in either self-etch (SE) or total-etch (TE) mode. Qualitative and quantitative margin analysis was assessed before/after fatigue simulation (n=8/group). Micro-CT examination was performed before/after polymerization of class-II restorations (Tetric EvoCeram BulkFill, Ivoclar-Vivadent, Schaan/Liechtenstein) (n=6/group). Volumetric shrinkage and shrinkage vectors were calculated. The internal interface was analyzed under scanning electron microscopy after cutting the teeth.ResultsThe μ-TBS test revealed no significant difference between excavation methods. Mean tensile strengths (MPa) were: polymer-bur/SE=16.0, polymer-bur/TE=16.7, carbide-bur/SE=15.5, carbide-bur/TE=20.3, dentin/SE=13.9, dentin/TE=24.1. Margin analysis rated all groups>99% of perfect margin in dentin and enamel, no influence of excavation methods was found. Micro-CT examination revealed no difference between groups concerning volumetric shrinkage (1.9-2.5%). The shrinkage direction was towards the bonded area. Polymer bur excavation resulted in an irregular surface and thicker smear layer than with carbide bur.ConclusionCaries excavation with a polymer bur does not negatively affect bonding performance to residual affected dentin. Etching with phosphoric acid can further strengthen the interface.
       
  • Differences in adhesion between 1C-PUR and MUF wood adhesives to
           (ligno)cellulosic surfaces revealed by nanoindentation
    • Abstract: Publication date: Available online 14 November 2019Source: International Journal of Adhesion and AdhesivesAuthor(s): Sabine Herzele, Hendrikus WG. van Herwijnen, Thomas Griesser, Wolfgang Gindl-Altmutter, Carina Rößler, Johannes Konnerth The chemical composition of adhesive and adherend involved in a bondline strongly influences the resulting adhesion performance. In this study, nanoindentation was used to mechanically characterize the interface between three chemically different (ligno)cellulosic fiber types and two chemically different adhesives. Regenerated cellulose, virgin wood, and thermally modified fibers were embedded in one-component polyurethane (1C-PUR) and melamine urea formaldehyde (MUF).The results from nanoindentation at the interface between 1C-PUR adhesive and the three fiber types show best adhesion towards the thermally modified fiber surface. In contrast, MUF shows almost identical adhesion behavior for all three fiber type surfaces. Differences in adhesion behavior due to varying fiber surface chemistry seem to be superseded by adhesive penetration into the bulk fiber, which is only expected for MUF adhesive.In addition, chemical surface analysis of the virgin wood and thermally modified fibers was carried out by X-ray Photon Spectroscopy and compared to literature values for regenerated cellulose. Cellulose values show the highest O/C ratio followed by virgin wood fibers and thermally modified fibers. These results are hinting on a higher amount of lignin or hydrophobic extractives on the thermally modified fiber surface. In terms of adhesion performance, these results indicate that the less polar thermally modified fibers surface seems to be favorable for 1C-PUR.
       
  • Fractographic analysis of the hygrothermal effect in co-bonded and
           secondary bonded joints under Mode II delamination loading
    • Abstract: Publication date: Available online 13 November 2019Source: International Journal of Adhesion and AdhesivesAuthor(s): Núbia N.A. Silveira, Rita C.M. Sales, Geraldo M. Cândido, Maurício V. Donadon Adhesive bonding technologies exhibit several advantages over conventional mechanical fasteners which include lower weight, reduced stress concentration in the adherents and excellent fatigue properties allowing the design of smooth surface contour and damage tolerant aerostructures. The overall structural performance of the composite joint depends on several factors related to the manufacturing process, such as surface preparation procedure, adhesive type, aging effects, and deficiency of inspection procedures. For this reason, there is a clear need to understand better how the joints behavior can be affected by them and the causes of their failure in order to improve the design and performance. In this context, this work presents the application of Scanning Electron Microscopy (SEM) technique to perform the fractographic analysis in two different types of joints namely co-bonded (CB) and secondary bonding (SB) that were submitted to a interlaminar fracture toughness tests under Mode II loading at Room Temperature Ambient (RTA) and Environmental Temperature Wet (ETW) conditions. The fracture surface of each sample submitted Mode II was prepared and analyzed regarding its failure aspects, enabling their association with the mechanical behavior of the samples during the fracture toughness tests and the values obtained. A detailed study on the fracture aspects of the composite joints was carried out correlating the fracture aspects with the mechanical behavior, type of processing and environmental conditioning in which each type of joint was tested, thus validating the use of these joints for operating conditions similar to those experienced in-service concerning aeronautical applications.
       
  • Understanding the interaction between bonding strength and strain
           distribution of plywood
    • Abstract: Publication date: Available online 13 November 2019Source: International Journal of Adhesion and AdhesivesAuthor(s): Wanzhao Li, Zheng Zhang, Guoqiang Zhou, Weiqi Leng, Changtong Mei Plywood is an important engineered wood product manufactured by orthotropically bonding veneers together. Bonding strength plays a crucial role in the performance of plywood. However the interaction between bonding strength and strain distribution has not been fully understood yet. Therefore, in this study, relationships between bonding strength and shear strain distribution in six types of plywood were illustrated using digital image correlation (DIC) approach as performing the lap-shear tests. Both urea formaldehyde (UF) and phenol formaldehyde (PF) resin were used as the bonding adhesive. Fluorescence microscopy was adopted to visualize the resin distribution within the micro-structure of the specimens. Results showed that the failure load (FL) of plywood positively and negatively correlated to the quantity of UF and PF resin, respectively. Increased quantity of UF resin facilitated to form a consecutive bond line, while large quantity of PF resin made the specimens brittle. Large ratio between load and strain, and homogenous strain distribution contribute to the high FL. Strain starts in regions adjacent to the notches and transfers to the remaining areas in the region of interest (ROI) by smoothly crossing the bond line. The properties of wood veneers play an important role in the bonding strength as strain is more likely to be started from the veneers. Findings of this study can contribute to the improvement of design strategies aiming the enhancement of the mechanical properties of plywood with small amount of resin.
       
  • Adhesion performance and optical properties of optically
           pressure-sensitive adhesives including an isosorbide
    • Abstract: Publication date: Available online 9 November 2019Source: International Journal of Adhesion and AdhesivesAuthor(s): Seung-Woo Lee, Jong-Ho Back, Gyu-Sung Shin, Seong-Wook Jang, Hyun-Joong Kim Isosorbide is newly used as a cross-linking agent to replace petroleum-based cross-linking agents for optically clear pressure-sensitive adhesives (PSAs). To control and determine the optimal concentration of isosorbide, the relationship between the glass transition temperature (Tg), referring to the viscoelastic characteristics of the organic polymeric materials as a key factor not only to synthesize the binders and but also to utilize the final products, and the concentration of isosorbide were investigated by measuring the optical properties, the adhesion performance via the peel strength, the probe tack, and the shear adhesion failure temperature. Consequently, it was found that the relationship provided by the linear plots between Tg and the other properties was strongly affected by the concentration of isosorbide due to the cross-linking density.
       
  • Pretreatment using diluted epoxy adhesive resin solution for improving
           bond strength between steel and wood surfaces
    • Abstract: Publication date: Available online 9 November 2019Source: International Journal of Adhesion and AdhesivesAuthor(s): Bo Tan, Yi Ji, Yunsen Hu, Bingyan Yuan, Xiaozhi Hu, Zhaohui Huang Interfacial bonding strength is critical to key structural functions in the laminar composite of different substrates bonded together by adhesives. This paper reports a study on utilization of the micro-porous composite structures of a hard-Australian jarrah wood to enhance the adhesive bonding with steel substrates. The thin adhesive joint between the two different substrates is rooted deeply into the micro-channels within the micro-porous composite structures of the jarrah wood using a unique resin pre-coating (RPC) technique. The mechanical abrasion of the substrates was carried out before RPC. Based on single lap shear tests, over 180% of improvement in shear strength was achieved after optimizing the concentration of RPC solution. One important observation was the wettability of substrates was enhanced by RPC as well. A non-destructive technique, X-ray tomography, was employed to reveal the microstructural details of jarrah wood, confirming the usefulness and effectiveness of RPC.
       
  • Bonding performance of melamine-urea–formaldehyde and
           phenol-resorcinol–formaldehyde adhesive glulams at elevated temperatures
           
    • Abstract: Publication date: Available online 8 November 2019Source: International Journal of Adhesion and AdhesivesAuthor(s): Jian Liu, Kong Yue, Liqin Xu, Jinhao Wu, Zhangjing Chen, Lu Wang, Weiqing Liu, Weidong Lu To better understand the bonding performance of glued laminated timbers (i.e., glulams) during fires, phenol–resorcinol–formaldehyde (PRF) and melamine–urea–formaldehyde (MUF) adhesives were used to investigate the effects of elevated temperatures on the glueline shear strength. The wood failure mode was observed to study the heat resistance of the two adhesives. Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) were used to analyze chemical and microscopic changes at various temperatures. The parallel-to-grain shear strength of solid larch wood decreased linearly with increasing temperature. Bonding strength of the wood–PRF glueline exposed to elevated temperatures was similar to that of the solid wood. The wood–MUF glueline exhibited good bonding performance at room temperature but showed poor thermal resistance. Shear strength of wood–MUF glueline was 0 MPa at 280 ºC. Bonding performances of PRF and MUF deteriorated linearly with increasing temperature. FTIR analysis showed that PRF could maintain a relatively intact chemical structure when the temperature was higher than 150ºC, and the structure of the MUF degraded significantly when the temperature was higher than 200 ºC.
       
  • Tannin plywood bioadhesives with non-volatile aldehydes generation by
           specific oxidation of mono- and disaccharides
    • Abstract: Publication date: Available online 5 November 2019Source: International Journal of Adhesion and AdhesivesAuthor(s): X. Xi, A. Pizzi, C.R. Frihart, L. Lorenz, C. Gerardin Sodium periodate has been shown to cleave glucose by specific oxidation to yield a number of non-volatile aldehydes which can react with the phenolic compounds in tannin extract and lead to tannin cross-linking and hardening. This approach to prepare a tannin resin usable for wood adhesives can be used by either treating with periodate a mixture of tannin and glucose, or to treat glucose beforehand with periodate to cleave it and generate the aldehydes, and only afterwards to mix it with the tannin. The results obtained with these two methods are identical, but the latter method avoids oxidation of tannin. The aldehydes were generated either by direct cleavage of glucose C-C bonds carrying vicinal oriented hydroxyls, or by recombination of the aldehydes so formed by aldol condensation or by water elimination between two aldehyde groups. MALDI ToF analysis indicated that all the three types of aldehydes appeared to react with the polyphenols in the tannin. Thermomechanical analysis (TMA) and plywood bonded with the tannin+glucose+ periodate mixes gave good bonding results, with dry, 24 hours cold water soaking and 3 hours at 63°C shear strength values improving concomitantly to the proportion of periodate used for the oxidation step.
       
  • Effect of Adhesive Joint Stiffness on Optimal Size of Large-format
           Cladding Comparison of Artificial and Real Environment
    • Abstract: Publication date: Available online 4 November 2019Source: International Journal of Adhesion and AdhesivesAuthor(s): Barbora Nečasová, Pavel Liška, Jiří Šlanhof, Barbora KovářováThe efficiency and lifespan of bonded façade joints can be increased and extended by designing the optimal size of the façade cladding. In the case of large-format cladding, the maximal possible size is always desired. The authors of this paper have scrutinised a relationship between the size of the façade cladding and the stiffness of the support, i.e. the bonded joint. In general, the higher the stiffness of the joint, the smaller the size of the cladding can be used in the design. After the experimental analysis of the material properties, very simple numerical approach with consideration of a linear stress-strain behaviour was chosen to determine the optimal size of the façade cladding. This paper investigates the material properties of selected adhesive systems, two of which are polyurethane-based and two are based on silyl modified polymers. The effect of the stiffness of the adhesive joint was assessed in combination with four different façade claddings (Cetris Basic, multilayer solid wood panel, solid timber plank and wood plastic composite) with a relatively high thermal and moisture expansion. It was, therefore, necessary for the bonded joint to be flexible and to adapt to these dimensional changes without creating greater internal tension. Moreover, the experimental part included artificial as well as real weathering conditions which allowed to compare the reliability of commonly used laboratory methods. While in combination with Cetris Basic the recorded data did not show any significant differences and the weathering method was less important than the chemical composition of the adhesive system, the results obtained in combination with solid wood panel demonstrated exactly the opposite. The joint stiffness with PU-I recorded after weathering in the real environment had dramatically increased, which led to the strength and adhesive elongation reduction by more than 50%, this also caused a premature failure of the bonded joint, and it greatly affected the cladding size that had to be reduced by 46%. Similar phenomenon was observed in combination with both MS-based adhesive systems after artificial weathering. Moreover, the size of the cladding had to be reduced by up to 56% in combination with MS-I after real weathering. On the other hand, the rigidity of PU-II and MS-II tested in the real environment had considerably decreased which allowed an enlargement of the cladding size by more than 30%.
       
 
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