Subjects -> MANUFACTURING AND TECHNOLOGY (Total: 363 journals)
    - CERAMICS, GLASS AND POTTERY (31 journals)
    - MACHINERY (34 journals)
    - MANUFACTURING AND TECHNOLOGY (223 journals)
    - METROLOGY AND STANDARDIZATION (6 journals)
    - PACKAGING (19 journals)
    - PAINTS AND PROTECTIVE COATINGS (4 journals)
    - PLASTICS (42 journals)
    - RUBBER (4 journals)

PLASTICS (42 journals)

Showing 1 - 39 of 39 Journals sorted by number of followers
Journal of Applied Polymer Science     Hybrid Journal   (Followers: 134)
Polymer     Hybrid Journal   (Followers: 88)
European Polymer Journal     Hybrid Journal   (Followers: 42)
Plastic and Polymer Technology     Open Access   (Followers: 40)
Plastic and Reconstructive Surgery     Hybrid Journal   (Followers: 31)
Additives for Polymers     Full-text available via subscription   (Followers: 20)
Reinforced Plastics     Full-text available via subscription   (Followers: 17)
Polymer Engineering & Science     Hybrid Journal   (Followers: 14)
Advances in Polymer Technology     Open Access   (Followers: 13)
ACS Applied Polymer Materials     Hybrid Journal   (Followers: 11)
Chinese Journal of Polymer Science     Hybrid Journal   (Followers: 9)
Acta Polymerica     Hybrid Journal   (Followers: 9)
Journal of Inorganic and Organometallic Polymers and Materials     Hybrid Journal   (Followers: 8)
Polymer Bulletin     Hybrid Journal   (Followers: 6)
Journal of Polymer Research     Hybrid Journal   (Followers: 6)
International Journal of Polymeric Materials     Hybrid Journal   (Followers: 6)
Journal of Polymer Science Part C : Polymer Letters     Hybrid Journal   (Followers: 5)
Polymer-Plastics Technology and Materials     Hybrid Journal   (Followers: 5)
Advanced Industrial and Engineering Polymer Research     Open Access   (Followers: 5)
Polymer Science Series B     Hybrid Journal   (Followers: 4)
Polymer Science, Series A     Hybrid Journal   (Followers: 3)
Polymer Science Series C     Hybrid Journal   (Followers: 3)
Polymer Science Series D     Hybrid Journal   (Followers: 3)
Iranian Journal of Polymer Science and Technology     Open Access   (Followers: 1)
Progress in Rubber, Plastics and Recycling Technology     Hybrid Journal   (Followers: 1)
Microplastics and Nanoplastics     Open Access   (Followers: 1)
High Performance Polymers     Hybrid Journal   (Followers: 1)
Journal of Polymers and the Environment     Hybrid Journal   (Followers: 1)
International Polymer Processing     Full-text available via subscription   (Followers: 1)
Journal of Plastic Film and Sheeting     Hybrid Journal   (Followers: 1)
Plastics Engineering     Partially Free   (Followers: 1)
Polymers from Renewable Resources     Hybrid Journal  
International Journal of Biobased Plastics     Open Access  
Polymers and Polymer Composites     Hybrid Journal  
SPE Polymers     Open Access  
Majalah Kulit, Karet, dan Plastik     Open Access  
Cirugia Plastica Ibero-Latinoamericana     Open Access  
Journal of Elastomers and Plastics     Hybrid Journal  
Journal of Cellular Plastics     Hybrid Journal  
Similar Journals
Journal Cover
Polymer Bulletin
Journal Prestige (SJR): 0.443
Citation Impact (citeScore): 2
Number of Followers: 6  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1436-2449 - ISSN (Online) 0170-0839
Published by Springer-Verlag Homepage  [2469 journals]
  • Dynamic mechanical characteristics of aged silicone rubber blend

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      Abstract: Abstract The effect of aging on the mechanical properties of silicone rubber (SR) was investigated by means of ultrasonic, dynamic mechanical analysis, and FTIR techniques. Both longitudinal and shear (Ultrasonic wave velocities) were measured at room temperature and at frequencies of 2 MHz. Density, molar volume, ultrasonic wave velocities, tensile strength, mechanical properties, and FT–IR showed the improvement of the silicone rubber network with aging time from 0 to 70 days, while loosening of the network structure was observed at 14 days and 50 days aging. These behaviours were explained in terms of the change in cross-link density and average stretching force constant of bonds with aging. Thermogravimetric analysis and differential scanning calorimetric techniques showed quite low thermal stability and temperature performance for aged SR at 14 and 50 days than virgin SR which was confirmed by the cracks and voids appeared under scanning electron microscope.
      PubDate: 2022-10-02
       
  • CMC-based edible coating composite films from Brewer's spent grain waste:
           a novel approach for the fresh strawberry package

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      Abstract: This study points to the coated strawberry with new edible films originating from the components of Brewer's spent grain (BSG) obtained as a large amount of waste during brewing. The aim of this study was to measure the high protein, phenolic compounds and cellulose from the BSG waste, which is created as waste in the brewing and mostly used as animal feed, with a new approach to coating strawberries. Cellulose, protein and phenolic compounds were extracted from BSG which is high in these components. Carboxyl methylcellulose (CMC) was synthesized from the obtained cellulose to produce edible films incorporated with different concentrations of protein and phenolic compounds of BSG. The production of the films was characterized by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), scanning electron micrographs (SEM) and mechanical analysis and their antioxidant activities. Weight loss, titration acidity, pH, soluble solids and anthocyanin content were determined for uncoated and coated strawberries with each formulation. Total phenolic was observed to be 2.28 mg GAE/g, and the total protein amount in BSG was observed to be 26.81 g per 100 g dry weight. The results showed that the protein and phenolic compounds used in CMC benefited the CMC film-coated strawberry and could be used as a food packaging material in future. The appearance of composite film-coated strawberry was better than that of uncoated films at the end of the 5 days of storage at room temperature due to the protective properties of the film. Graphical abstract
      PubDate: 2022-10-02
       
  • Selective detection of Fe (III) via fluorescence turn-on mechanism with
           Rhodamine tethered poly(vinyl amine) microbeads

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      Abstract: New reusable rhodamine tethered microbeads-based chemosensor was prepared and its fluorescent behaviors toward various transition-metal ions were investigated. Firstly, almost monodisperse (~ 2–5 µm in size) poly(vinyl formamide-co-ethylene glycol dimethacrylate) microbeads (Poly(VFA-co-EGDMA)) were prepared via precipitation polymerization. After hydrolysis of the microbeads in basic medium, terephthalaldehyde was tethered onto the microbeads via imine linkages. Subsequently, rhodamine hydrazide was linked to the resulting aldehyde functional microbeads in the same manner. The structural transformation of each step and the morphology of the microbeads were evaluated by FTIR and SEM, respectively. Rhodamine-decorated microbeads exhibited selective detection abilities on Fe (III) ions with high precision through the fluorescence turn-on mechanism. The limit of detection was found to be 1.5 µM. The job’s plot indicated a complexation ability as 1:1 stoichiometry between the chemosensor and Fe 3+ ion. The Benesi–Hildebrand plot revealed a binding constant (Ka) of 7 × 104 mol/L and the average fluorescence lifetime was measured as 48.9 ± 3.0 ns. From the material point of view, either the small particle size with a high surface area or crosslinked nature provided excellent sensing ability and stability of the microbeads in a heterogeneous medium. Besides, due to its densely crosslinked structure, rod beads can be easily reused after the ligand exchange process by simple filtration, which is a very important advantage for chemosensor recycling. These features offer a potential application as a chemosensor of Fe 3+ ion in aqueous solution. Graphic abstract
      PubDate: 2022-10-01
       
  • Effect of chain extender length and molecular architecture on phase
           separation and rheological properties of ether-based polyurethanes

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      Abstract: Abstract Different types of chain extenders in the synthesis of polyurethanes affect its structural, mechanical, and rheological properties. Effects of chain extender length, functionality, and molar ratio of the reactants on different properties of polyurethane elastomers based on poly (oxytetramethylene)glycol as the soft segment and toluene diisocyanate as the hard segment were investigated. Polyurethane samples were synthesized using different chain extenders including glycerol as the trifunctional and 1,2-propanediol, 1,4-butanediol, and 1,6-hexanediol as the bi-functional hydroxyl-containing chemicals. Fourier-transform infrared spectroscopy, X-ray diffraction, rheomechanical analysis, dynamic mechanical thermal analysis, differential scanning calorimetry, and stress–strain analysis were used for characterization of the products. By phase separation of the hard and soft segments, two different glass transition temperatures were observed. Increasing phase separation and degree of hydrogen bonding between the chain extender and diisocynates in the hard segments were resulted in higher mechanical properties. With increasing the amount of hard segment, a higher polymer toughness is determined due to higher degree of hydrogen bonding.
      PubDate: 2022-10-01
       
  • Microalgal biomass as renewable biofiller in natural rubber compounds

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      Abstract: Abstract Microalgal biomasses, consisting of micronized Spirulina Platensis and its low protein fraction, were investigated in this work as possible renewable biofillers in natural rubber compounds, with the aim of replacing the commonly used carbon black. Natural rubber, in some cases blended with 10% of epoxidized natural rubber to improve the matrix-filler affinity, was compounded with 25, 35, 50 and 75 phr of each biomass. Compounds with 25, 35 and 50 phr of carbon black N990 were also prepared as benchmarks. After compounding, vulcanization times were determined by dynamic mechanical analysis. Rubbers were vulcanized by compression moulding and characterized by means of morphological analysis (scanning electron microscopy), thermal analysis (thermogravimetric analysis, dynamic mechanical thermal analysis) and mechanical tests (tensile tests, strain induced crystallization detection by X-ray diffraction, pure shear fracture tests). Microalgal biomass turned out to be homogeneously dispersed in natural rubber matrix and the materials obtained required lower curing times compared to carbon black compounds. It was found that, up to 50 phr, Spirulina has the ability to increase rubber tensile strength and modulus, acting similarly to N990, while decreasing rubber thermal stability and fracture toughness.
      PubDate: 2022-10-01
       
  • Batch and column studies for adsorption of naphthalene from its aqueous
           solution using nanochitosan/sodium alginate composite

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      Abstract: Abstract The current experimental study involves the synthesis and characterization of nanochitosan/sodium alginate composite (NC/Na-Alg) and utilized for the adsorptive removal of naphthalene from its aqueous solution. The NC/Na-Alg was primarily characterized using electron microscopy, Fourier transform spectrometer and X-ray diffractometer analysis. The operating process conditions such as pH, time, initial concentration, composite dosage and temperature were investigated on percentage degradation. The isotherm pattern and kinetic follow-up were fitted well with Freundlich mechanism and pseudo-second order, respectively, and the adsorption equilibrium capacity was estimated to be 55 mg/g. The thermodynamic analysis of adsorption revealed the physical and exothermic process. The column experiments produced optimum values at bed height, inlet flow rate of solution and initial naphthalene concentration of 150 mm, 10 mL/min and 50 mg/L, respectively. Also, the current study exhibited that the application of deacetylation method for NC/Na-Alg synthesis could be a productive approach for competing sequestration of naphthalene in the environment.
      PubDate: 2022-10-01
       
  • TPU nanocomposites tailored by graphene nanoplatelets: the investigation
           of dispersion approaches and annealing treatment on thermal and mechanical
           properties

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      Abstract: Abstract The present work investigates the combined effect of the addition of graphene nanoplatelets (GNPs) to the thermoplastic polyurethane copolymer (TPU) and thermal treatment evaluation of the resultant TPU/GNP nanocomposite. Thus, this factor can be evaluated through a variety of dynamic mechanical and thermal measurements. The TPUs as nanocomposites were synthesised by three different approaches of mixing (in situ polymerisation melt compounding and solution mixing) with different weight ratios. Various dispersion processes were employed to obtain better dispersed GNP and thus strong interaction, leading to an effective performance of the TPU/GNP system. X-Ray diffraction and Raman spectroscopy tests displayed the inter-spacing planar quality of GNP nanofillers. Dynamic mechanical analysis revealed that the storage modulus (Eʹ) of TPU nanocomposites how a significant performance particularly at 20 wt.%, 10 wt.% and 5 wt.% of GNP for in situ polymerisation melt compounding and solution mixing, respectively. The microphase-separated structure of TPU nanocomposite samples after thermal treatment (at 80 °C for 4 days) was investigated from for all dispersion methods. Consequently, the overall TPU crystallinity decreased after thermal treatment compared with untreated samples, presuming an ordering suppression of hard segments that involved with GNP. Dispersion and interaction of GNP can play a crucial role in enhancing the thermal and mechanical properties, and thus, a significant improvement for TPU nanocomposites. The tensile test showed significant enhancement with GNP incorporation before thermal treatment. On the contrary, a deterioration in tensile modulus and tensile strength resulted from thermal treatment. A modified Halpin–Tsai model was utilised to predict the mismatch between the empirical and theoretical results. It found a clear diversity in modulus of TPU/GNP samples, in particular at greater GNP content.
      PubDate: 2022-10-01
       
  • Optimization of microencapsulation of metronidazole in alginate microbeads
           for purpose of controlled release

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      Abstract: To obtain the optimum conditions for encapsulation of metronidazole in sodium alginate, a response surface methodology (RSM) was used to find out the effect of independent variables (alginate concentration and drug to alginate ratio) on dependent variables including mean particle size, yield, drug loading, and encapsulation efficiency. Furthermore, the effect of alginate concentration on swelling behavior of microbeads was evaluated, and the mechanism of drug release was also studied. On the basis of the results, it can be declared that spherical microbeads with mean particle sizes of 443–665 µm were obtained with process yields, drug loading, and encapsulation efficiencies of almost 79.5%, 54.9%, and 79.9%, respectively. The metronidazole release was found to be 68% in 7 h with a formulation containing the drug to polymer ratio of 2:1. The optimum values for alginate concentration and drug to alginate ratio were determined to be within 1.4% (w/v) and 2.85 (w/w), respectively. Graphic abstract
      PubDate: 2022-10-01
       
  • Polybutylene succinate (PBS)/acrylonitrile butadiene styrene (ABS)
           membrane with improved mechanical properties for wastewater treatment

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      Abstract: Abstract The low mechanical properties of polybutylene succinate (PBS) limit its applications in the preparation of biodegradable filtration membranes. In this work, acrylonitrile butadiene styrene (ABS) was used to improve the mechanical properties of filtration membranes for the first time. Polybutylene succinate (PBS)/acrylonitrile butadiene styrene (ABS) blends containing 10, 20, and 30 wt% ABS were prepared by dissolving in N-methyl-2-pyrrolidone (NMP), and then membranes were prepared through immersion precipitation. Surface and cross-sectional scanning electron microscopy (SEM), porosity measurement, Fourier transform infrared spectroscopy (FTIR), water contact angle and water content measurements, tensile test, and thermogravimetric analysis (TGA) were conducted to characterize the membranes. Filtration experiments were performed to treat fruit juice production wastewater to determine the rejection of turbidity and chemical oxygen demand (COD). Also, the membrane tendency to fouling was assessed. The results of mechanical properties showed that with increasing the amount of ABS, the mechanical properties of the samples improved so that by increasing the ABS loading to 10, 20, and 30 wt%, the tensile strength increased by 44%, 131%, and 188%, and the elastic modulus increased by 17%, 78%, and 99%, respectively, compared to the mechanical properties of pure PBS. The blend membranes had less tendency to irreversible fouling than the neat PBS membrane regarding the filtration results. The results of wastewater filtration indicate that the COD rejection dropped and steady permeate flux raised with increasing ABS amount. All the membranes rejected 100% of turbidity and thus can be utilized in wastewater pretreatment.
      PubDate: 2022-10-01
       
  • Multiscale effect of graphene oxide with short carbon fiber for property
           improvement of room temperature vulcanized silicone rubber

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      Abstract: Abstract Graphene oxide (GO) has been widely used as a multi-functional filler in various composites. In order to improve the properties of room temperature vulcanized (RTV) silicone rubber, the functionalized GO (FGO) was used as 2-dimensional filler with short carbon fiber (SCF) and silica particle. The effects of the FGO content on the properties of the RTV silicone rubber composites were investigated. When appropriate amount of the FGOs is added in the composite, the interfacial bonding between SCFs and silicone rubber matrix could be effectively enhanced and the properties of the composites are improved. For the composite with 0.5 phr FGO, the tensile and tear strengths are about 4.7 MPa and 21.9 kN/m, respectively. Meanwhile, the corresponding values of the composite without FGO are only 4.0 MPa and 20.3 kN/m, respectively. The above said values of the composite with 1 phr FGO are 3.8 MPa and 19.8 kN/m, respectively. In addition, the onset decomposition temperature and temperature at the highest decomposition rate for the composite with 0.5 phr FGO, both remarkably increase from 493.4 to 504.2 °C and 564.4 to 613.1 °C, respectively. The carbon frameworks (dense layer and porous layer) will form during the ablation process and play the key role in protecting the RTV silicone rubber, which leads to the reduction of the ablative rate.
      PubDate: 2022-10-01
       
  • Investigations into Ag
           nanoparticles–carbon–poly(9,9-di-n-octylfluorenyl-2,7-diyl) (PFO)
           composite: morphological, structural, optical, and electrical
           characterization

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      Abstract: Abstract The incorporation of different materials can improve the properties of conductive polymers to become composites. This paper studies the morphological, structural, optical, and electrical effects of adding different weight ratios of silver nanoparticles (Ag NPs)-carbon (C) mixture into poly(9,9-di-n-octylfluorenyl-2,7-diyl) (PFO) polymer by a low-cost and straightforward method. The thin films are prepared by drop-casting the prepared composite onto silicon substrates. Transmission electron microscopy shows Ag NPs embedded into the carbon. Field emission scanning electron microscopy images show increased Ag NPs-carbon particle size in PFO. The weight ratio increases due to aggregation, consistent with decreasing band gap trend from the Tauc plot. Ultraviolet–visible (UV–Vis) spectroscopy shows a redshift pattern of the central peak of PFO as the weight ratio increases. Photoluminescence and Raman spectra show that Ag NPs-carbon mixture increases β-phase percentage in PFO due to poor solvent effect. Lastly, the 10% Ag NPs-carbon-PFO sample exhibits the highest electrical conductivity among the three samples studied. A proposed schematic diagram shows how Ag NPs-C particles influence the morphology of the PFO chain and electrical properties of PFO-Ag NPs-C composite.
      PubDate: 2022-10-01
       
  • Replacement of ZnO by ecofriendly synthesized MgO in the NBR vulcanization

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      Abstract: Abstract Rubber compounds contain several additives besides the elastomer matrix, such as fillers, curing agents, activators, antioxidants, among others. However, some of these additives causes a negative impact on the environment, e.g., zinc oxide commonly used as activator in the vulcanization process. Thus, in this study, ecofriendly synthesized magnesium oxide was evaluated as substitute to ZnO in a standard nitrile rubber composition. Additionally, commercial magnesium oxide was also included in study to be used as a reference. All rubber compounds were evaluated in terms of rheometric (minimum and maximum torques, curing times), rheological (dynamic moduli), and mechanical (tear resistance, tensile resistance, hardness, and stress relaxation) properties and crosslink density. The marching-modulus was more noticeable when MgO and green-MgO was employed as activator. The vulcanization of NBR with MgO and green-MgO resulted in rubber materials with higher crosslink density, higher elastic moduli, lower phase angle δ, and lower stress relaxation than ZnO composites. Besides that, no significant difference was observed for the mechanical performance regarding tear strength, tensile strength, and hardness.
      PubDate: 2022-10-01
       
  • Effect of dispersants on cytotoxic properties of magnetic nanoparticles: a
           review

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      Abstract: Abstract Magnetic nanoparticles (MNPs) are widely investigated to evaluate their efficacy for therapeutic carriers, biosensors, contrast agents, therapeutic agents (hyperthermia generators), antimicrobial agents, etc., in extracellular space. When MNPs are used for biomedical applications, the nanoparticles are usually dispersed in phosphate buffer saline or body fluids. Bare MNPs tends  to agglomerate and aggregate due to high specific surface energy and magnetic dipolar interactions. Further non-specific adsorption of proteins and salts on bare MNPs leads to collapse of colloidal properties. In order to mitigate the above problems, bare MNPs are ligated with biocompatible dispersants for colloidal stability. Majority MNPs are ligated with dispersants such as oleic acid, oleylamine, dopamine derivatives, zwitterionic compounds and polyethylene glycol, to obtain surfactant ligand monolayer on MNPs. Sometimes, polymers are also used as capping agent or encapsulation material. Surfactant monolayer can further be functionalized with therapeutics, proteins, immunoreceptor, etc., for a specific application. Hence one need to understand biocompatible properties, especially cytotoxicity, of nanoparticles with different dispersant monolayers. In addition, biocompatibility testing is also important because the presence of extractable chemical compounds and agents from synthesis process may influence biocompatibility. Cytotoxicity is most sensitive of the biocompatibility tests and is useful for evaluating these types of harmful reactions. Effect of dispersants on cytotoxicity of MNPs are not reviewed in the literature. The effect of various dispersant on cytocompatibility of various MNPs are systematically presented here. Among all, polyethylene glycol polymer is a universal dispersant with high colloidal stability and very low cytotoxicity. Short-chain zwitterionic surfactant ligands are next best dispersants.
      PubDate: 2022-10-01
       
  • Assessing two dominant methods of dental composites linear polymerization
           shrinkage management: macromonomers and prepolymerized fillers

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      Abstract: Abstract Recently, many dental composites labeled as low shrinkage have been presented. However, corporations obscure either the production procedure or the brand new formula’s impact on mechanical properties, which led us toward choosing two outstanding controlling routes of polymerization shrinkage (specifically designed macromonomers and prepolymerized fillers (P.P.F.)) to compare their actual advantage and disadvantage in terms of mechanical properties. Macromonomers were synthesized by using a magnetic stirrer during two stages, using HEMA, Caprolactone, IPDI, and 1,6-Hexanediol for the whole macromonomer structure. For P.P.F. synthesis, a composite mixture has been prepared in which instead of photo-initiators, benzoyl peroxide and benzophenone were added following by polymerization in an ordinary oven with a temperature of 100 °C. In this study, we found that any formula with great amount of P.P.F. (20% of fillers portion) results in a brittle composite, which was due to both high viscosity and heterogeneity. Furthermore, great percentage of P.P.F. is accompanied by the lowest ceramic filler percentage among the entire groups, and as a result, such formula shows the lowest microhardness (82.8 kg/mm2). On the other hand, adding high percentage of macromonomer (%20 of resin portion) brings about both high polymerization shrinkage (%2.56) and weakened mechanical properties (97.9 MPa for flexural strength) resulting from lower percent of Bis-GMA in comparison with other groups. Our findings proved that only the combination of two methods has the capability to be considered in mass production and what that greatly impresses the polymerization shrinkage is P.P.F. in the entire groups. The other conclusion of this study is that the application of nanofillers is mandatory if it is intended to control shrinkage with two mentioned routes.
      PubDate: 2022-10-01
       
  • Rheological study of microcrystalline cellulose/pyridinium-based ionic
           liquids solutions

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      Abstract: Abstract Two ionic liquids, N-hexylpyridinium acetate [HPyr][Ac] and N-hexylpyridinium trifluoroacetate [HPyr][TFA], have been synthesized and studied as a dispersing solvent of microcrystalline cellulose (MCC). After the synthesis of both ionic liquids, their chemical structure was confirmed by Fourier-transform infrared spectroscopy. MCC/ionic liquids (ILs) solutions were then prepared at different concentrations (0.25, 0.5, 1, 2, 5, and 10% wt) and characterized in terms of rheological properties. Afterward, the viscosity of MCC/IL solutions was measured using an advanced rheometer under steady-shear flow at different temperatures (20–80 °C). At concentrations less than 2% wt, the solutions of the MCC/ILs exhibit the behavior of a Newtonian fluid, regardless of temperature, indicating the high dispersion of the MCC colloids. Once the concentration reached 2% wt, the MCC/[HPyr] [Ac] solutions exhibited shear-thinning behavior at low shear rates, whereas the MCC/[HPyr][TFA] solutions exhibited shear-thickening behavior. The first behavior was caused by an increase in the concentration of MCCs in contact with the anions [Ac]−, which resulted in a strong repulsion between them. The second behavior was caused by a weak interaction between the anion [TFA]− and the hydroxyl groups of cellulose, which contributed to the formation of a network of MCC molecule aggregates at higher concentrations. Despite this, the MCC/[HPyr][Ac] and MCC/[HPyr][TFA] solutions have the same entanglement concentration (Ce = 5 wt%) at which the polymers start to overlap. Furthermore, with 10 wt% MCC, the activation energy of MCC/[HPyr][Ac] and MCC/[HPyr][TFA] increases by 34.77% and 39.75%, respectively. Similarly, increasing the temperature decreases viscosity and leads to highly homogeneous MCC/ILs solutions. These results confirmed the dispersal ability of [HPyr][Ac] compared to [HPyr][TFA], resulting in increased local intermolecular interactions between polymer chains and [HPyr][Ac] ionic liquid.
      PubDate: 2022-10-01
       
  • Development of PAMAM dendrimer-modified magnetic chitosan: a novel
           platform for α-amylase immobilization

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      Abstract: The two generations of PAMAM-modified magnetic chitosan have been synthesized and are employed as enzyme carriers due to their biocompatibility and high affinity toward the biomolecules. This is the first attempt to use these carriers in the field of enzyme immobilization and is found to be about 93.95% immobilization efficiency by adsorption with second generation of the modified dendritic polymer (CSM-PAMAM G2). Here, α-amylase was also immobilized on CSM-PAMAM G2 by covalent binding method using gluteraldehyde as cross-linking agent in the range of 0.1–1% and found to be optimum immobilized enzyme activity at 0.4% which has been taken for further experimental studies. The immobilized enzymes by both methods have shown wider range of pH stability and exhibited about 60–75% of relative activity at pH 9. They have demonstrated broader temperature stability, and both have shown optimum activity at 60 °C. The effect of polymer concentration on enzyme activity was studied, and the optimum value is found to be at 0.2 g/mL. They have acquired about 85–90% of thermal stability due to their adequate conformational stability that protect from thermal unfolding. The km values 0.53 ± 0.04, 0.85 ± 0.03 and Vmax values 23.25 ± 0.04, 16.67 ± 0.06 for adsorbed and covalently immobilized enzyme confirmed their high affinity and improved activity. They retained 40–60% of relative activities after six months of storage, and the remarkable reuse assay was found to be that the carriers are very easy to handle due to their magnetic separation which will extend their application in many industrial fields. Graphical abstract
      PubDate: 2022-10-01
       
  • Production of biodegradable sodium caseinate film containing titanium
           oxide nanoparticles and grape seed essence and investigation of
           physicochemical properties

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      Abstract: Abstract In this study, sodium caseinate film was produced and the effect of titanium oxide nanoparticles and grape seed essence as factors that enhance film properties was investigated. For this purpose, nanocomposite films based on sodium caseinate were modified with different levels of nanoparticles of 0 to 1.5% and grape seed essence at levels of 0 to 500 ppm based on the central composite experimental design (CCD). The effects of these variables on physical/mechanical properties, water vapor permeability, and antioxidant properties were investigated. The morphology and chemical structure of different films were evaluated by SEM and FTIR techniques. The results showed that the addition of titanium oxide nanoparticles has improved the mechanical properties of the films. In this regard, films prepared from 1.5% and 500 ppm nanoparticles have the highest tensile strength. The results of scanning electron microscopy test showed that the addition of nanoparticles led to the indirect penetration of water, which reduced the permeability of the films to water vapor to 4.89 kg/m. The addition of grape seed essence caused the antioxidant effects of the produced films, so that the films containing 250 ppm showed antioxidant activity of 86.74%. Overall, the results showed that the addition of nanoparticles and grape seed essence had positive effects on the physical and chemical properties of sodium caseinate.
      PubDate: 2022-10-01
       
  • Evaluation of electrospun nanofibers fabricated using PCL/PVP and
           PVA/β-TCP as potential scaffolds for bone tissue engineering

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      Abstract: Abstract In order to create a perfect bone scaffold, nanocomposites are the best options, as they can be engineered to have the composition, structure and properties of natural bone. In the present study, the layer-by-layer and hybrid nanofiber scaffold are fabricated by electrospinning method using a combination of PCL/PVP and PVA/β-TCP layers. We study and compare the morphological properties (scanning electron microscope (SEM), swelling ratio and porosity), mechanical properties (tensile strength, elongation at break and tensile modulus) and biodegradability of the scaffolds. The average fiber diameter measured for layer-by-layer and hybrid scaffolds is 446 ± 128 nm and 505 ± 261 nm, respectively. The tensile strength for the layer-by-layer and hybrid scaffolds is 7.40 ± 3.40 MPa and 6.57 ± 1.64 MPa, respectively, and the degradation rate for layer-by-layer and hybrid scaffolds is 26 ± 2% and 40 ± 5%, respectively. So the results show the desired mechanical properties and compatibility of scaffolds. The (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) (MTT) assay shows cell viability above 80% and absence of cell cytotoxicity for layer-by-layer and hybrid scaffolds after 3, 5 and 7 days of rat marrow stromal cell (rMSC) culture. The morphology and proliferation of rMSC cells show the suitability of the scaffolds for tissue engineering application. Therefore, both types of scaffolds can be used in several tissue engineering applications, including improvement of bone tissue regeneration.
      PubDate: 2022-10-01
       
  • Adsorption of malachite green on the modified montmorillonite/xanthan
           gum-sodium alginate hybrid nanocomposite

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      Abstract: Abstract In this study, montmorillonite (MMT)/xanthan gum (XG)-sodium alginate (Alg) hybrid hydrogel nanocomposite has been synthesized for adsorption of malachite green (MG) from aqueous solution. The MMT nanoparticles were modified by cetyltrimethylammonium bromide (CTAB), with specific fraction of the critical micelle concentration (CMC) of CTAB, and applied to synthesize MMT(0.5CMC)/XG-Alg, MMT(1CMC)/XG-Alg and MMT(2CMC)/XG-Alg, and unmodified MMT nanoparticles were applied to synthesis MMT/XG-Alg as control adsorbent. BET, FTIR and SEM analyses were conducted, in order to identify the structure and morphologies of hybrid nanocomposites. The results of FTIR, showed that the functional groups of carboxylates and hydroxyl in the structure of the nanocomposite play an important role in the adsorption process. According to SEM analysis, the unevenness on the adsorbents surface has disappeared, due to the adsorption of the MG dye. Also, by the surface modification of MMT nanoparticles using CTAB, the MMT(0.5CMC)/XG-Alg specific surface area increased from 6.38 to 72.48 m2/g, compared to MMT/XG-Alg. Maximum adsorption capacity was occurred in pH = 6, temperature 318 K, contact time 240 min and 0.02 g/50 mL of the hybrid nanocomposites. According to the results, adsorption process was fitted on the Langmuir isotherm model, with maximum adsorption capacity of 769.23 mg/g for the MMT(0.5CMC)/XG-Alg as the best adsorbent, and 476.19, 666.66 and 588.23 mg/g for the MMT/XG-Alg, MMT(1CMC)/XG-Alg and MMT(2CMC)/XG-Alg, respectively. Adsorption kinetics is well described by the pseudo-second order. The thermodynamic parameters, the enthalpy (∆H°) and Gibbs-free-energy (∆G°), indicated that sorption process was endothermic and spontaneous, respectively.
      PubDate: 2022-10-01
       
  • Chia oil performance as healing agent for epoxy resin-based smart coatings

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      Abstract: The drying properties and the performance of the chia oil (CO) as a novel healing agent for self-healing coatings are reported in this work, in comparison with linseed oil (LO). The drying properties of both oils were estimated by their respective drying rates (D.R.) between 0 and 500 h by Fourier-transform infrared spectroscopy. The D.R. of CO at 216 h was 47% higher than LO, which was attributed to its higher polyunsaturated fatty acids content. CO and LO were encapsulated in poly(urea–formaldehyde) microcapsules by in situ polymerization in oil-in-water emulsion, showing mean diameters of 20 and 23 µm, respectively. Coatings loaded with 10 wt% of microcapsules were applied onto AISI 1020 steel surfaces. The effect of these drying oils as healing agents for self-healing coatings was evaluated by artificial scratches and measured by potentiodynamic polarization test (PPT) and electrochemical impedance spectroscopy (EIS) techniques. Scratched samples showed an increasing corrosion potential of only 4 h after the scratch simulation, according to the PPT. EIS results showed that coatings containing CO as a healing agent had lower double-layer capacitance (QPE2-Q), suggesting a slight improved self-healing effect compared to LO. Graphic abstract
      PubDate: 2022-10-01
       
 
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