JournalTOCs

Advances in Polymer Technology
Journal Prestige (SJR): 0.299

Citation Impact (citeScore): 1
Number of Followers: 14

This is an Open Access Journal

Open Access journal
ISSN (Print) 0730-6679 - ISSN (Online) 1098-2329
Published by Hindawi

[339 journals]

Categories and Application Fields and Manufacturing Process and Action
Mechanism of Water Retaining Agent
- Abstract: Water retaining agent (WRA) is a kind of functional polymer material with strong water absorption capacity. It can absorb and release water repeatedly and is often used for crop growth in water shortage areas. It is of great significance to the development of water-saving agriculture. There are many kinds of water retaining agents, and with the development of science and technology, the raw materials for making water retaining agents tend to be diversified. And they are more and more widely used in many fields closely related to our life, such as industry, food production, medical treatment, and greening, and the manufacturing process is more and more mature. In addition, the water absorption capacity of water retaining agent is not only related to its own components but also related to the external environment. The water absorption mechanism and the factors affecting water absorption capacity of water retaining agent were explored as follows.
  PubDate: Thu, 16 Jun 2022 07:05:01 +000
Water Absorption Behavior of Teff (Eragrostis tef) Straw Fiber-Reinforced
Epoxy Composite: RSM-Based Statistical Modeling and Kinetic Analysis
- Abstract: Recently, reinforced polymeric composites prepared from natural fibers have received a significant interest among the researchers because of its appreciable sustainability, environmentally friendly, and low cost. However, one particular issue, that is, hydrophilic property, still needs to be addressed for its successful applications. Since the hydrophilic tendency of natural fibers is extremely undesirable, it leads to the quick degradation of fiber-based polymer composites. Hence, the fiber property, hydrophilic nature, is influenced by the presence of noncrystalline and voids part of these fibers that significantly influences the polymer matrix adhesion. Hence, it is very important to understand the water absorption behavior of reinforced fiber composites. In this study, a crop residual material specific to Ethiopia, teff straw (Eragrostis tef), was used as fiber material. The fiber was treated with 1% NaOH followed by 1% CH2=CHCOOH at room temperature for improving the bonding strength between the fiber and polymer, which leads to suppress the water absorption. The investigation on mathematical model for water absorption property at different fiber loadings (4%, 8%, 12%, 16, and 20%) was carried out, and the analysis on the kinetic behavior of water absorption was also investigated. In addition, the response surface-based statistical modeling which correlates water absorption, fiber loading, and time has been analyzed.
  PubDate: Wed, 15 Jun 2022 05:50:02 +000
Investigation of Curing Mechanism and Mechanical Properties of
Polypropylene/Aliphatic Epoxy Composites
- Abstract: Temperature-sensitive cure kinetics based on bisphenol A oligomeric diglycidyl ether and branching diphenylmethane di-isocyanate, polymer aliphatic or lower molecular weight aromatic amines, and polypropylene and epoxy composites were examined. Polypropylene networks are formed initially, followed by amine hardeners interfering with epoxy oxirane rings to frame linear oligomers. Finally, the system is formed by a reaction between amines obtained in the second phase and epoxy oxirane rings during the curing step. This three-stage treatment was illustrated. The activation energy was calculated using the Flynn-Wall-Ozawa and Kissinger-Akahira-Sunose isoconversational approaches to cure degree. The Ea-to- correlation was determined using these approaches, revealing that the research curing systems exhibited autocatalytic effects. Among the materials studied, compounds with low molecular weight aromatic amines had the strongest and longest-lasting tensile characteristics. There are numerous advantages to slow curing and discrete stages of composite creation, including better mechanical properties.
  PubDate: Mon, 13 Jun 2022 12:20:01 +000
Design and Optimization of Fuel Cells: A Case Study on Polymer Electrolyte
Membrane Fuel Cell Power Systems for Portable Applications
- Abstract: Fuel cells are energy conversion devices that directly convert chemical energy of fuels such as hydrogen to useful work with negligible environmental impact and high efficiency. This study deals with thermodynamic analysis and modeling of polymer electrolyte membrane fuel cell (PEMFC) power systems for portable applications. In this regard, a case study of powering a computer with a PEMFC is presented. Also, an inclusive evaluation of various parameters such as voltage polarization, overall system efficiency, power output, and heat generation is reported. In addition, a parametric study is conducted to study the effect of many design and operation parameters on the overall efficiency. Results show the direct influence of current density and temperature values on optimization of the design parameters in PEMFCs.
  PubDate: Mon, 13 Jun 2022 08:35:01 +000
Investigation on Reinforcement Effects of Nanocellulose on the Mechanical
Properties, Water Absorption Capacity, Biodegradability, Optical
Properties, and Thermal Stability of a Polyvinyl Alcohol Nanocomposite
Film
- Abstract: This paper presents the reinforcement of nanocellulose (NC) in polyvinyl alcohol (PVA) to examine the effect of the amount of reinforcement on the properties of PVA. The nanocellulose was successfully extracted by sulfuric acid hydrolysis method and ultrasonication, and successively reinforced with polyvinyl alcohol by the solvent-casting method. After incorporating nanocellulose into the PVA matrix, the effect of nanocellulose on the tensile strength, elongation at break, water absorption capacity, transmittance, thermal stability, and biodegradability of PVA was investigated. The tensile strength increased from to and with the addition of 2%NC and 5%NC, respectively. The elongation at break increased from to with 2%NC, and after the reinforcement of 7%NC, it decreased to . The water absorption capacity result reveals that neat PVA absorbs the highest amount of water which is and is reduced to by adding 2%NC. By increasing the nanocellulose loading to 7%, the water intake capacity was reduced to which illustrates the water intake was reduced linearly with the increment of NC. The ultraviolet-visible (UV-Vis) result implies that the transmittance of neat PVA and PVA-2%NC composite film was 85.4% and 78.2% at 600 nm, respectively, which indicates the decrement in transmittance. The thermogravimetry analysis (TGA) reveals that the thermal stability of polyvinyl alcohol after incorporating nanocellulose particles was reduced. The weight loss of neat PVA is after 90 days while the weight loss of the PVA composite films reinforced with 1%, 3%, 5%, 7%, and 9% was ,,,, and , respectively. The scanning electron microscopy micrograph for the PVA-6%NC nanocomposite film reveals a dispersion of nanocellulose in a matrix.
  PubDate: Fri, 03 Jun 2022 08:05:01 +000
Effect of Nanoclay Filler on Fatigue Life of Natural
Rubber/Styrene-Butadiene Blend
- Abstract: In this paper, the fatigue life of natural rubber (NR)/styrene-butadiene rubber (SBR) compound is evaluated experimentally. The parameters investigated are the NR, SBR, and nanoclay loading in the composition, strain amplitude, and the frequency of the fatigue test. Fracture surfaces of NR/SBR/nanoclay compound are investigated using scanning electron microscopy (SEM). The results show that by increasing NR and the nanoclay loading in the rubber composition, the fatigue life of the rubber increases. For the nanoclay, a threshold value exists beyond which the fatigue life of the rubber compound decreases. It is also observed that by increasing the test frequency, the fatigue life of the rubber compound decreased. Tensile, hardness, and dynamic mechanical thermal analysis (DMTA) tests were also performed to evaluate the mechanical and thermal properties of the compound. SEM results show that by increasing the strain amplitude, the test specimens fail softly, and the addition of nanoparticles roughens the fracture surface and increases the fatigue life.
  PubDate: Sat, 28 May 2022 08:35:00 +000
Mechanical Properties of Arecanut and GFR Hybrid Polypropylene Composites
- Abstract: The mechanical characteristics of hybrid polypropylene composites may be enhanced by adjusting the fibre loading and ratio, according to this study. The hot press technique was utilised to generate a variety of composites with four different amounts of fibre loading. In addition, the fibre ratio in composites with a 20-weight-percent fibre loading was changed. The composites were characterised using Fourier transform infrared analysis as well as tensile, flexural, and hardness tests. In the composites that have been created, Fourier transform infrared examination showed that hemicelluloses, lignins, and moisture were present, all of which have the potential to reduce tensile strength. Fibre loading resulted in a decrease in tensile strength but an increase in Young’s modulus. With increasing fibre loading, flexural modulus and hardness rose, whereas flexural strength declined. The best mechanical qualities were found in a composite made primarily of arecanut and glass fibres, with a weight ratio of 1 : 3.
  PubDate: Mon, 16 May 2022 12:20:00 +000
Fiber Orientation Analysis of Overflow Water-Assisted Injection Molding
with Short Glass Fiber Reinforced Polypropylene
- Abstract: The fiber orientation is playing an important performance indexed for glass fiber reinforced polypropylene for water-assisted injection molding. Based on the viscoelastic constitutive equation (White-Metzner) and the fiber orientation model (iARD-RPR), the effects of fiber mass content, water injection delay time, water injection pressure, and melt temperature, which are on the fiber orientation along the flow direction and shear rate distribution of the melt, were investigated. Studies found that the orientation degree of the fiber along the flow direction was reduced with the increase of the fiber mass content, the extension of the water injection delay time, and the improvement of the melt temperature and that the orientation degree of the fiber along the flow direction was raised with the increase of the water injection pressure flow in the laminar flow state, but it was reduced with the increase in the turbulent state. It can be further learned from the shear rate distribution that decreasing fiber mass content, reducing the water injection delay time, lower melt temperature, and increasing water injection pressure in laminar flow conditions will increase the shear rate in the channel layer and the shear rate gradient along the thickness direction of the melt, while the water injection pressure in the turbulent state is on the contrary.
  PubDate: Fri, 13 May 2022 23:58:02 +000
Preparation and Characteristic of Polyurethane Powder Adhesives with
Heating Resistance Modified by Nanosilica
- Abstract: Polyurethane powder adhesives (PPAs) have a great application prospect in various areas. However, the weakly adhesion property at high temperature greatly hindered its application. In this study, nanosilica as reinforcing agent and dispersing agent has been introduced during the preparation of PPAs. A series of the polyurethane powder adhesives modified by nanosilica were prepared and the influence of adding order of nanosilica on the heat resistance and adhesive strength properties of PPAs has been investigated. The results showed that the T-peel strength of most samples after second heat (heated at 70°C for 24 hours) decreased about 60-80% comparing with the original T-peel strength. However, PPSY only decreased 17.5%, which indicated the nanosilica added after the chain extension reaction, in the prepolymer synthesis could increase the heat resistance performance of polyurethane powder adhesives. It also means the nanosilica was doped between the PU chains keeping the original form as enhancement reagent adding the nanosilica after the chain extension reaction. The excellent heat resistance performance of PPSY could meet the requirements of the industrial gluing in the fields of footwear.
  PubDate: Fri, 13 May 2022 10:50:01 +000
Polymer Processing under Microwaves
- Abstract: Over the last decades, microwave heating has experienced a great development and reached various domains of application, especially in material processing. In the field of polymers, this unusual source of energy showed important advantages arising from the direct microwave/matter interaction. Indeed, microwave heating allows regio-, chemio-, and stereo-selectivity, faster chemical reactions, and higher yields even in solvent-free processes. Thus, this heating mode provides a good alternative to the conventional heating by reducing time and energy consumption, hence reducing the costs and ecological impact of polymer chemistry and processing. This review states some achievements in the use of microwaves as energy source during the synthesis and transformation of polymers. Both in-solution and free-solvent processes are described at different scales, with comparison between microwave and conventional heating.
  PubDate: Fri, 06 May 2022 12:20:01 +000
Production and Characterization of Maximum Liquid Oil Products through
Individual and Copyrolysis of Pressed Neem Oil Cake and Waste Thermocol
Mixture
- Abstract: In this study, individual and copyrolysis experiments were performed with pressed neem oil cake (NOC) and waste thermocol (WT) to produce high grade liquid oil. The effects of reactor temperature, heating rate, feed ratio, and reaction time on product yields were investigated to identify the optimum parameters for maximum oil yield. The maximum oil yield of 49.3 wt%, 73.4 wt% and 88.5 wt% was obtained from NOC pyrolysis, copyrolysis, and WT pyrolysis under optimized conditions. During copyrolysis, the maximum oil product was obtained under NOC/WT ratio of 1 : 2 and at the temperature of 550°C. The liquid oils obtained from thermal and copyrolysis were subjected to detailed physicochemical analysis. When compared to biomass pyrolysis, the copyrolysis of WT and NOC had a substantial improvement in oil properties. The copyrolysis oil shows higher heating value of 40.3 MJ/kg with reduced water content. In addition to that, the copyrolysis oil obtained under optimized conditions is analyzed with Fourier transform infrared spectroscopy (FT-IR) and Gas chromatography–mass spectrometry (GC-MS) analysis to determine the chemical characterization. The analysis showed the presence of aliphatic and aromatic hydrocarbons in the oil.
  PubDate: Thu, 05 May 2022 11:50:02 +000
Mechanical Properties of Ramie/Hemp Hybrid Composites Influenced by
Stacking Arrangement and NaOH Treatment
- Abstract: This research is aimed at seeing how different stacking sequences and chemical treatments impact the mechanical characteristics of ramie–hemp composites. Hand-lay-up procedures were used to create a blend of woven ramie and hemp fibers. The woven ramie was treated with a diluted 6% sodium hydroxide (NaOH) solution to compare the mechanical properties of preserved and unpreserved ramie hybrid composites. According to the findings, the tensile properties of hybrid composites are better in three-layer composites than in four-layer composites. Hemp-based hybrid composites outperform other hybrid composites in terms of mechanical properties. Hybrid composites that have been treated have better tensile and flexural properties than hybrid composites that have not been treated. The sample H/R/H/R was found to have the best impact characteristics. This research is part of a more extensive investigation of hybrid composite’s application in high-velocity impact applications.
  PubDate: Thu, 05 May 2022 06:35:01 +000
Model-Based Study of Creep and Recovery of a Glassy Polymer
- Abstract: Polyvinyl chloride specimens were subjected to three different constant loads at ambient temperature, and the creep is monitored as a function of time. After a certain time, the load was withdrawn and the strain recovery was followed with time. Although the deformational behavior of such material is conventionally described by the Burger model consisting of elastic, viscoelastic, and viscous components, in the present work, it is shown that the whole creep recovery process is reversible and is described by three viscoelastic components connected in series. Depending on the relative value of the observation and the relaxation times, the viscoelastic components appear pseudo- elastic or viscous. It is found that the model parameters evaluated from the creep data fail to predict the recovery data in both the initial and the end phases, while those from the recovery data can partially reproduce the creep data (satisfactorily in the late phase and with high deviation in the initial phase). The model parameters vary with stress values, but with a good approximation, they could be averaged for a certain stress range to describe creep processes for a specified time period. The proposed model describes creep data better than the Finley and the Weibull models.
  PubDate: Mon, 02 May 2022 05:05:02 +000
Mechanical Behaviour of Alkali-Treated Fabric-Reinforced Polymer Matrix
Composites
- Abstract: Polyethylene (PE) was used as a composite material to create a fabric containing 40% pineapple, 30% jute, and 30% cotton fibres by weight. The physical characterisation is carried out, like deterioration and water absorption tests. PE-based composites were shown to have a lower water absorption rate when dipped in deionized water to perform an absorption test. Fabric/PE composites decomposed slowly in the soil during the degradation test. Alkali solution of 5 percent, 7 percent, and 9 percent sodium hydroxide by weight for 60 minutes was studied as alkali impact mechanical characteristics: mechanical testing’s like tensile strength and modulus, elongation at break, bending strength, and modulus. Data investigation exposed that the tensile strength and modulus, elongation at break, bending strength, and composite modulus values were 64 MPa and 871 MPa, 23.14 percent, 45 MPa, and 512 MPa. There were tensile strength and modulus, elongation at break, bending strength, and modulus of the neat polyethylene sheet that were 32Mpa and 342 MPa, 79 percent, 22 MPa, and 234 MPa, respectively. Compared to a polyethylene sheet, composite values for tensile strength and modulus, bending strength, and modulus raised by 107%, 156%, 110%, and 115% as a result of fabric reinforcing.
  PubDate: Thu, 28 Apr 2022 11:35:01 +000
Investigation on Physical and Mechanical Characteristics of Date Palm
Fiber Reinforced Aliphatic Epoxy Hybrid Composites
- Abstract: Automotive industry attention in using date palm fiber as an internal material has been sparked by its use as a polymer reinforced composite. Date palm fiber-reinforced aliphatic epoxy composites for semistructural applications are the key goals of this work. To make the various composites, they used a combination of manual lay-up and adhesive bonding. Date palm fiber/bamboo hybrid composite and uncontaminated composites were tested through density, tensile, flexural, and impact tests and also studied the effects of swelling, water absorption, and physical performance in greater depth. According to studies, hybrid composites constructed from date palm fiber and bamboo had the best mechanical properties. The date palm/bamboo hybrid composite was created to impact the toughness of 12.72 J/m in tensile, flexural strength, and impact toughness measurements. The reduced swelling and water absorption were 27.66 percent and 15.37 percent, respectively, when testing a date palm fiber/bamboo hybrid composite. Density ranged from 1.15 g/cm3 to 1.25 g/cm3 for bamboo fiber composite material and from 1.23 to 1.27 g/cm3 for date palm fiber/bamboo composite material. High flexural strength is achieved by the bamboo composite specimen (bamboo: 6.18 MPa), followed by (PDF-/: 61.12 MPa, date palm fiber-AA/: 61.08 MPa, date palm fiber-/: 60.82 MPa, and date palm fiber-/: 61.47 MPa), and the PDF composite specimens (date palm fiber-/: 61.112). Hybridized materials (date palm fiber/bamboo fiber) with a 50 : 50 ratio had higher impact strength.
  PubDate: Tue, 26 Apr 2022 09:05:00 +000
Investigating the Effects of Nonsolvent Additive and Spinning Conditions
on Morphology and Permeation of PAN Hollow Fiber Membranes
- Abstract: In this study, polyacrylonitrile hollow fiber (PAN HF) membranes were designed and fabricated with desired morphology and permeability for low pressure-driven applications via the dry-wet phase-inversion spinning process. The effects of multiple design and fabrication parameters on permeation, morphology, thickness, and pore size of membranes were investigated using various techniques. Moreover, the effects of water as the nonsolvent additive, chemical composition of the bore solution, dope solution flow rate, air gap, coagulation bath temperature, and tensile ratio (take-up speed) were investigated. The addition of 3% wt. water as the nonsolvent additive into the dope solution resulted in a seventeen-times increment in the water flux up to 495 L m-2 h-1 bar-1. It showed a significant improvement in membrane porosity compared with those prepared without water nonsolvent additive. Utilization of 90% wt. of the solvent in water solution as the bore solution instead of pure water showed the most significant effect on the water flux and membrane structure among the fabrication parameters. It resulted in a reduction in threshold permeation pressure by more than ten times. The results revealed that whichever variation, including increased dope solution flow rate or coagulation bath temperature, or reduced air gap or traction, leads to promotion of membrane water flux. Still, different effects on the structure and morphology of the membranes were observed. Based on the outcomes of this study and according to the SEM images, one can conclude that outer surface pore size reduction from about 300 nm resulted in decreased water flux from 448 to 226 L m-2 h-1 bar-1, so that no pores were observed in the outer surface until 50 K magnification of the SEM image. The findings in this study provide instructive guidelines for the design and fabrication of high-performance hydrophilic PAN-based hollow fiber membranes with the desired morphology and water flux. Best ranges of investigated parameters for relatively high permeate water flux and desired membrane morphology were reported.
  PubDate: Fri, 22 Apr 2022 07:50:03 +000
Mechanical Properties of Polymer Composites Reinforced with
Alkaline-Treated Natural Fibre
- Abstract: The mechanical characteristics of a high impact polyethylene composite (HIPC) reinforced with abaca fibre (AF) are investigated in relation to fibre loading. An alkaline behaviour was used to improve the characteristics of the abaca fibre. With a fibre length of 100 mm, five different fibre loadings of the abaca fibre were used to create the samples of the composite (25, 35, 45, 55, and 65 wt percent). The object was made using compression moulding with unidirectional fibre orientation. The influence of fibre loading was investigated using tensile, hardness, and density tests. In an experiment, it was shown that with 55 percent fibre loading, tensile strength was 312 percent higher than without, and Young’s modulus was 545 percent higher than without. While this was happening, the hardness and density of the AF/PE composites were found to be quite similar, with minor increases from 25 wt percent to 65 wt percent AF loading in comparison to the control sample’s zero wt percent AF loading. 67.42 Shore-D and 1.014 g/cm3 are the highest values. The alkaline treatment of the AF/PE composite had a substantial influence on mechanical characteristics, according to the findings.
  PubDate: Thu, 21 Apr 2022 06:20:00 +000
Mechanical Behaviour and Thermal Properties of Pine Apple Leaf Fiber
Reinforced Vinyl Ester Composites
- Abstract: Despite its mechanical and environmental properties, pineapple leaf fibers (PALF) are used as a home threading material in India. In addition, the effects of abrasive combing and pretreatment techniques on fiber and composite characteristics were examined in this work. Using PALF vascular bundles separated from different regions of the leaves did not affect the mechanical aspects of pineapple leaf fiber-vinyl ester composites. PALF fibers performed equally in strengthening composite flexural properties under static loading, regardless of diameter or location, with a much lower weight percentage and combined pressure. Tests at higher speeds revealed that the PALF-vinyl ester composite was more robust with more delicate bundles. Reinforcing composites that do not require a high degree of hardness can benefit from the cleaner, more delicate bundles produced by abrasive combing.
  PubDate: Tue, 19 Apr 2022 09:50:00 +000
Mitochondria-Targeting and ROS-Responsive Nanocarriers via Amphiphilic
TPP-PEG-TK-Ce6 for Nanoenabled Photodynamic Therapy
- Abstract: Designing targeted-delivering and stimuli-responsive nanocarriers for photodynamic therapy (PDT) is an appealing method, especially, targeting delivery of photosensitizers to mitochondria as the most sensitive cellular organelles to reactive oxygen species (ROS) could significantly enhance the therapeutic efficacy of PDT. In this study, we synthesized triphenylphosphonium bonded PEG-NH2 (TPP-PEG-NH2) and bridged to chlorin e6 (Ce6) via thioketal (TK) linkage to obtain red light-triggered, amphiphilic copolymer (TPP-PEG-TK-Ce6), which could self-assemble into micelles with an average size of 160 nm and zeta potential of +20.1 mV. The in vitro release behavior of TPP-PEG-TK-Ce6 nanocarriers showed a light-activated way and was dependent on the H2O2 concentration. TPP-PEG-TK-Ce6 nanocarriers exhibited high cytotoxicity against C6 cells with illumination. Confocal laser scanning microscopy observation indicated that TPP-PEG-TK-Ce6 nanocarriers were efficiently internalized into the mitochondrion of C6 cells, released Ce6 via light activated. By contrast, in the case of TPP-PEG-NH2 directly bonded Ce6 (TPP-PEG-Ce6) nanocarriers, little Ce6 was found in the mitochondrion. The stronger fluorescence in the mitochondrion of TPP-PEG-TK-Ce6 nanocarriers originated from the mitochondrial-targeting capability of TPP and the cleavage of TK linkages activated by light irradiation, which greatly improved the cellular uptake of TPP-PEG-TK-Ce6 nanocarriers and released more Ce6 in the mitochondrion. This work provided a facile strategy to improve PDT efficacy.
  PubDate: Wed, 13 Apr 2022 10:20:04 +000
Investigation on Mechanical Properties of Bamboo and Coconut Fiber with
Epoxy Hybrid Polymer Composite
- Abstract: The present study focused to improve material characteristics and quality in terms of the NaOH concentration for treating the coconut and bamboo fiber to enhance the mechanical properties of natural fiber polymer-based hybrid composites. The NaOH-treated fibers were washed thoroughly using distilled water and allowed to dry for 24 hours. Composition of each specimen, bamboo (B) and coconut (C) fiber with epoxy composite, was prepared by hand layup process as per the American Society for Testing and Materials (ASTM) standard. The proportionality of the material was carefully fulfilled according to the previous literature reports. The weight fraction of the composite material content was set to be 30% and 70% of epoxy (E) resin and isolated fibers. Three distinct criteria were used to calculate mechanical parameters such as tensile strength, flexural strength, and material hardness. It was found that the combination of 70% E with 30% BC of hybridized composite had a maximum tensile strength of 62.42 MPa, whereas the flexural strength and hardness of the other combinations, such as 70% E with 30% C and 70% E with 30% B, were observed to be 58 MPa and 185 HRC (Hardness Rockwell C), respectively.
  PubDate: Tue, 12 Apr 2022 07:50:02 +000
Adhesive and Impact-Peel Strength Improvement of Epoxy Resins Modified
with Mono and Diamine Functionalized Elastomers
- Abstract: Epoxy resins are widely applied in the automotive and electronic industries. However, pure epoxy resins are brittle and thus possess poor mechanical properties. Herein, we report a facile method for improving the impact-peel and adhesive strengths of epoxy resins via the incorporation of two different types of polyether amines (monoamine-based and diamine-based prepolymers). A comparative study was performed to investigate the potential advantages of incorporating a prepolymer into an epoxy resin matrix. It was discovered that the incorporation of a diamine prepolymer significantly improved the impact-peel strength of the epoxy resin system at low (-40°C) and room (23°C) temperatures. For 15 wt% adhesive loading, the diamine prepolymer-based epoxy system demonstrated a 130% (low temperature) and 32% (room temperature) higher impact-peel strength than the monoamine prepolymer-based epoxy system. Moreover, the 15 wt% diamine prepolymer-based epoxy system exhibited a significantly improved shear strength (~36 MPa) and T-peel strength (260 N/25 mm) owing to the effectively reduced crack propagation and cohesive interactions between the epoxy molecules. Our results suggest that the modification of epoxy resins with an appropriate amount of mono and diamine-functionalized elastomers provides a novel route for the development of highly efficient adhesive materials for various applications.
  PubDate: Mon, 11 Apr 2022 12:20:00 +000
The Effect of Starch and Magnetite on the Physicochemical Properties of
Polyurethane Composites for Hyperthermia Treatment
- Abstract: In this study, modified polyurethanes (PUs) with starch and magnetite were synthesized in the form of scaffolds for potential applications in orthopedics. Polyurethanes were synthesized using a one-step method. PU synthesis was carried out using poly(ε-caprolactone) 2000 as soft segments and 4,4-methylenediphenyl diisocyanate (MDI). Various molar ratios of starch and 1,5-pentanediol (PDO) as crosslinker/chain extender were applied, and the effects of incorporating different amounts of magnetite, as well as the role of PDO to starch ratio, were studied. The use of the additive in the form of magnetic particles was to feature the polyurethane materials for use in hyperthermia. The prepared polyurethanes were investigated using Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetry (TG), and dynamic mechanical analysis (DMA) methods. Scanning electron microscopy (SEM)/energy-dispersive X-ray spectroscopy (EDX) analysis and preliminary bioactivity assessment were also performed. The addition of magnetic particles did not cause significant changes in the properties of the obtained materials compared to starch. The tested materials have the potential to be used to fill or replace bone defects in orthopedics, where they can undergo hyperthermia treatment.
  PubDate: Wed, 06 Apr 2022 14:50:02 +000
Impact of Placement of Aminopropyl Triethoxy Silane and Tetraethoxy
Silicate on SSBR Chains: Analysis of Rolling Resistance, Wet Grip, and
Abrasion Resistance
- Abstract: Solution styrene-butadiene rubber (SBR) and silica filler have attracted a significant attention because of their superior properties in cured rubber mixtures used in automobile tire industry. One of the challenges ahead of using these materials is the hard dispersion of silica with its polar surface in SBR nonpolar rubber. In the present study, the synthesis of styrene-butadiene rubber by solution polymerization method with polymer chain modification using copolymer functionalization was performed. For this purpose, two materials, namely, aminopropyl triethoxy silane (APTES) and tetraethoxy silicate (TEOS), were employed to improve the silica dispersion in the mixture. The results of postsynthesis structural tests show the successful placement of functional groups on the polymer chain. The results of mechanical, dynamic, and imaging analyses of the cured mixtures showed an improvement in the APTES-containing samples rolling resistance, wet surface grip, and abrasion resistance by 39%, 18%, and 17%, respectively, due to having stronger physical and chemical bonds with silica and also the usage of end agents in the polymer chain. The samples containing TEOS had also better results than the conventional SBR rubber. In addition, a sample containing emulsion styrene-butadiene rubber was prepared to compare its properties with those of the solution SBR. Another SBR sample containing silane coupling agent was also prepared to investigate its performance compared to that of the agents placed on the polymer chain. The abrasion resistance, rolling resistance, and wet grip of the coupling agent containing sample showed 2%, 10%, and 30% improvement, respectively, which were very close to those of the sample containing the TEOS agent. In this work, various techniques including, rheometry, wear, rolling, hardness, bound rubber content, dynamic mechanical thermal analysis (DMTA), and field emission scanning electron microscopy (FE-SEM) were employed to analyze the synthesized rubber.
  PubDate: Tue, 05 Apr 2022 08:50:01 +000
Manufacturing and Separation Characteristics of Hemodialysis Membranes to
Improve Toxin Removal Rate
- Abstract: With the recently growing interest in health care, hemodialysis is being performed not only to treat patients with renal disease but also to improve blood circulation. At present, filters used for hemodialysis are manufactured only in certain countries, and all other countries must rely on imports. In this study, polyethersulfone (PES), which has excellent blood compatibility, was used as the main material to develop hemodialysis membranes for hemodialysis filters, and these hemodialysis membranes were prepared by adding a hydrophilic polymer, polyvinylpyrrolidone (PVP), and varying the type of nonsolvent during the manufacturing process to improve the toxin removal rate and biocompatibility. The addition of PVP was confirmed through attenuated total reflection Fourier transform infrared (ATR-FTIR), and the structure of the membranes depending on the nonsolvent was analyzed through scanning electron microscopy (SEM) and atomic force microscopy (AFM) images. The contact angle results indicated that the hydrophilicity of the membrane surface was improved as the concentration of PVP increased. The results of the toxin filtration efficiency experiment using urea, creatinine, and bovine serum albumin (BSA) confirmed removal rates of 58.8% and 56.87%, respectively, and a protein loss of less than 8%. Also, cell viability was over 90% at the PVP concentration of 2% or higher. A preliminary study was conducted on the improvement of toxin filtration efficiency and the development potential of these hemodialysis membranes with excellent biocompatibility.
  PubDate: Sun, 27 Mar 2022 12:05:03 +000
Development of Starch-Based Bioplastic from Jackfruit Seed
- Abstract: In this article, jackfruit seed starch plasticized with common plasticizers was developed and characterized. At the first step, the research papers that dealt with the fabrication and characterization of starch-based bioplastics were synthesized and analyzed. Next, jackfruit seeds were selected as a source for starch because of their large availability, low price or even free, and high starch capacity. Afterward, a starch-based bioplastic fabrication procedure was proposed. From preliminary tests, plasticizers were sufficiently selected, including water, glycerol, natri bicarbonate, and acid citric. Using different combinations of these plasticizers, four types of bioplastics were then fabricated to study the effect of the plasticizers as well as to characterize the properties of the corresponding bioplastics. A cutting tool for ASTM D412 type A standard tensile testing specimen was then designed and fabricated. Using these dog-bone specimens, tensile results showed that the hardness of the fabricated bioplastic was positively proportional to the ratio of the starch. Furthermore, from SEM characterization, the bioplastic specimens were fully plasticized. Although the fabricated bioplastic has lower mechanical properties than petroleum-based plastics, its environmental friendliness and high potential added value promise to be a material of the future.
  PubDate: Sat, 26 Mar 2022 08:05:02 +000
Date Palm Fiber-Reinforced Recycled Polymer Composites: Synthesis and
Characterization
- Abstract: In this research study, Recycled Polymer (RP) composites are synthesized by using compression molding process, initial mixtures of RP and Date Palm Fibers (DPF) with four different lengths (e.g., 2.5, 5, 7.5, and 10 mm) and weight ratios (e.g., 5, 10, 15, and 20 wt%). The RP composites utilized in this study are polyethylene and polypropylene. The mixtures of RP and DPF are heated at 80°C and then poured into a priori prepared mold. The mold is designed to have three cavities for three specimens in order to characterize them through impact, creep, and tensile tests. The results showed that the hardness and impact increased with this process. In addition, an increase in the DPF up to 15 wt% was observed with a small increase in the DPF length. High creep resistance was also observed to be 10 mm with 20 wt% in the DPF specimens. The maximum strain was obtained in a 2.5 mm fiber length with 5% of DPF due to ductility of the plastic matrix. Moreover, with a small ratio of tough DPF, short fibers are unable to block or resist rapid plastic deformation in specimens. In fact, the DPF specimens of 10 mm length with 20 wt% exhibit a high tensile strength of 78 N/mm2 in comparison with other composite specimens. This is due to the length and content of fibers, which improve transferring action and microfailure modes.
  PubDate: Wed, 23 Mar 2022 12:05:01 +000
Laminarin Alleviates the Ischemia/Reperfusion Injury in PC12 Cells via
Regulation of PTEN/PI3K/AKT Pathway
- Abstract: Objective. To investigate the protective effect of laminarin on PC12 cells damaged by oxygen glucose deprivation/reoxygenation (OGD/R) and its molecular mechanism. Methods. PC12 cells in the logarithmic phase were randomly divided into the control group, OGD/R group, and OGD/R+laminarin (0.5, 2.5, and 5 μg/ml) group. CCK-8 activity assay kit was used to detect cell viability. ELISA kit was performed to examine the levels of proinflammatory factors (TNF-α, IL-1β, and IL-6) and oxidative stress markers (ROS, LDH, and MPO). In addition, flow cytometry was employed to determine cell cycle and apoptosis. The expression of cell proliferation-related proteins (PCNA and Ki67), apoptosis-related proteins (Bcl-2, Bax, and Caspase-3), and PTEN/PI3K/AKT pathway-related proteins was evaluated by Western blot. Results. Compared with the control group, the cell viability was decreased significantly in the OGD/R group. CCK-8 results showed that laminarin could attenuate the damage of PC12 cell viability induced by OGD/R in a concentration-dependent manner. Meanwhile, the highest concentration of 5 μg/ml laminarin could significantly promote the viability of PC12 cells and the expression of PCNA and Ki67 than the OGD/R group. Additionally, ELISA assays showed that laminarin significantly inhibited the expression of proinflammatory factors (TNF-α, IL-1β, and IL-6) and the levels of oxidative stress markers (ROS, LDH, and MPO). Flow cytometry results demonstrated that laminarin promoted the cell cycle. And laminin upregulated the expression of apoptotic protein Bcl-2, while downregulated the expression of apoptotic proteins Bax and Caspase-3. Finally, laminarin significantly suppressed the expression of PTEN and facilitated the expression of PI3K and p-AKT compared to the OGD/R group. Conclusion. Laminarin could alleviate the OGD/R-induced PC12 cell neuronal injury via promoting cell activity and cycle and inhibiting inflammation, oxidative stress, and apoptosis. The mechanism may be related to the downregulation of PTEN protein and the activation of the PI3K/AKT pathway.
  PubDate: Fri, 18 Mar 2022 11:05:02 +000
Utilization of Waste Textile Cotton by Synthesizing Sodium Carboxymethyl
Cellulose: An Approach to Minimize Textile Solid Waste
- Abstract: This research uses waste textile cotton (WTC) from the textile industry as a raw material to synthesize sodium carboxymethyl cellulose (CMC) by adapting a modified etherification methodology. Yields of technical CMC (TCMC), semipurified CMC (SPCMC), and purified CMC (PCMC) were g, g, and g, respectively, per gram of cotton waste. Degree of substitution (DS) values of PCMC, SPCMC, and TCMC was ,, and , respectively. For PCMC, SPCMC, and TCMC, the purity of the prepared different grades of CMC was %, %, and %, respectively. Fourier transform infrared spectroscopy (FTIR) peak values were 3437 cm-1, 1609 cm-1, and 1427 cm-1, proving WTC conversion to CMC. Furthermore, values of X-ray diffraction (XRD) peaks were 9.7 and 20.5, confirming the transformation of WTC to CMC as well. Thermogravimetric analysis (TGA) and scanning electron microscope (SEM) have been assessed to define CMC’s thermal stability and morphology, respectively.
  PubDate: Fri, 11 Mar 2022 07:50:00 +000
Electroresponsive Hydrogel-Based Switching Components for Soft,
Bioelectrical, and Fluidic Circuits
- Abstract: The development of various soft components for fluid circuits is conducive to the further development of soft robots. The electroresponsive hydrogel is applied to build a functional oscillator in the study conducted. Based on the multiphasic mixture model, the deformation of the hydrogel under external electric fields is analyzed through COMSOL Multiphysics simulator. Owing to the characteristics of the hydrogel that it will deform in response to electric field, the hydrogel is employed to control fluidic circuits, resulting in a novel controllable functional soft oscillator.
  PubDate: Tue, 08 Mar 2022 08:50:02 +000
Development of Biodegradable Delivery Systems Containing Novel
1,2,4-Trioxolane Based on Bacterial Polyhydroxyalkanoates
- Abstract: In this work, delivery systems in the form of microparticles and films containing 1,2,4-trioxolane (ozonide, OZ) based on polyhydroxyalkanoates (PHAs) were developed. Main systems’ characteristics were investigated: the particle yield, average diameter, zeta potential, surface morphology, loading capacity, and drug release profile of microparticles, as well as surface morphology and release profiles of OZ-containing films. PHA-based OZ-loaded microparticles have been found to have satisfactory size, zeta potential, and ozonide loading-release behavior. It was noted that OZ content influenced the surface morphology of obtained systems.
  PubDate: Mon, 28 Feb 2022 14:05:02 +000