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This research investigates the effects of the frequency of the external electric field during the curing process on the interfacial properties of epoxy composites reinforced by Mendong fiber. Epoxy was used as a matrix with cycloaliphatic amine as a curing agent. The AC electric field by frequencies of 1, 2, and 3 kHz and strength of 750 V/cm were applied during the curing process. The functional groups, structure, interface properties, and morphology of treated epoxy were observed using Fourier‐transform infrared, x‐ray diffraction, scanning electron microscope, and pull‐out test, respectively. The result indicates that after treatment with an electric field of 1 kHz, new peaks were observed in the epoxy diffractogram at the angle of 6.2° and 12.3°, change in morphology, the wettability properties of epoxy were increased and interface shear strength was improved. Increasing the frequency of electric fields results in more damage to the interface and subsequently reduces the shear strength at the interface. Highlights: Interface properties of the composite after curing in an electric field characterized.Exposure to electric field frequency during curing changed epoxy properties.Shear strength of Mendong fiber/epoxy varied post‐exposure to the electric field. [ABSTRACT FROM AUTHOR]

Ecocomposites were produced by incorporating coconut shell powder (CSP) into polylactic acid (PLA) resin. The effect of filler content and chemical modification on the mechanical properties, thermal properties, and morphology of PLA/CSP ecocomposites were investigated. The addition of filler has decreased the tensile strength and elongation at break of PLA/CSP ecocomposites. However, tensile strength and modulus of elasticity of PLA/CSP ecocomposites were enhanced by maleic acid treatment. Meanwhile, glass transition temperature ([T.sub.g]) and crystallinity ([X.sub.c]) of PLA/CSP eco-composites increased at 30 php of filler content and increased the presence of maleic acid (MA). However, the melting temperature ([T.sub.m]) and crystallization temperature ([T.sub.c]) were not significantly changed with the filler content and MA modification The thermal stability of PLA/CSP ecocomposites increased with the CSP content. The MA modification improved the thermal stability of PLA/CSP ecocomposites through better filler-matrix interaction. The improvement was confirmed by scanning electron microscope study. POLYM. ENG. SCI., 53:1109-1116, 2013. © 2012 Society of Plastics Engineers, INTRODUCTION Biodegradable plastic materials have greatly increased the interest among researches and industrials owing to the ecological problem including the accumulation of plastic waste. The rate of plastic waste generation [...]

The aim of the research was to utilize cocoa pod husk (CPH) in polypropylene (PP) biocomposites. Maleated polypropylene (MAPP) was used as coupling agent to improve the properties of PP/CPH biocomposites. The addition of MAPP had increased the stabilization torque of PP/CPH biocomposites. The tensile strength and modulus of PP/CPH with MAPP were higher compared to PP/CPH biocomposites without MAPP, except the elongation at break decreased. The crystallinity and thermal stability of PP/CPH biocomposites with MAPP increased. These improvements were due to the enhanced interfacial bonding between CPH and PP matrix, which were proved by SEM analysis. [ABSTRACT FROM AUTHOR]

Cocoa pod husk (CPH) is a waste material from cocoa industry. This work describes the development of biocomposites from polypropylene and cocoa pod husk. 3-aminopropyltriethoxysilane (3-APE) is used as coupling agent in filler treatment of CPH. The treated CPH with 3-APE had raised the stabilization torque of PP/CPH biocomposites. The results of tensile test and scanning electron microscope (SEM) indicated that 3-APE given coupling effect on PP/ CPH biocomposites. The presence of covalent bonds between CPH and 3-APE was confirmed by Fourier transmission infra-red (FTIR) analysis, while the improvement of thermal stability and crystallization were evidenced by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). [ABSTRACT FROM AUTHOR]

This paper compares the effects of different forms of vulcanized natural rubbers on the physical, mechanical, thermal, and electrical performances of filled epoxy systems. In this study, natural rubber (NR), liquid natural rubber (LNR), and recycled natural rubber (rNR) were introduced into filled epoxy systems. The results show that flexural strength, modulus, and toughness properties of filled epoxy system were enhanced with NR phases, as compared to those with LNR and rNR. Scanning electron micrograph revealed that the particle sizes of NR phases dispersed within epoxy matrix were smaller and more uniform, as compared to those with LNR and rNR phases. Incorporation of NR phases has improved the thermal stability of filled system, followed by LNR and rNR. This is attributed to more heat energy needed to overcome good interfacial bonding between epoxy matrix and small NR phases. X‐ray diffraction analysis result showed that filled epoxy/NR/GNP system has higher 2θ values, indicated that d‐spacing in between GNP nano‐fillers has the closer distance. Electrical bulk conductivity values of filled epoxy/NR/GNP system were the highest. Small NR phases acted as elastomer spacers, which provided better "GNP packing efficiency" and realigned the GNP nano‐fillers to form more effective conductive pathways for electrons hopping. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47188. [ABSTRACT FROM AUTHOR]

This paper focus in comparing un-vulcanized and vulcanized NR as toughening agent in epoxy resin. The incorporation of graphene nano-platelets (GNP) into two-matrix system has yield conductive materials whilst maintained their polymeric characteristics. Filled systems were prepared via magnetic stirring method and dispersion of GNP in the filled systems using ultrasonic water bath. The aim of this study is to investigate the effect of NR content on physical, mechanical, thermal and electrical performances of un-vulcanized and vulcanized filled systems. There is a great improvement in mechanical properties of vulcanized filled systems as compared to un-vulcanized filled systems. The results showed that the addition of vulcanized NR content at 5 vol% has improved flexural strength, modulus and toughness by 41.28%, 11.9% and 36.26% as compared to un-vulcanized filled system, when comparing at the same NR content. This improvement is attributed to the semi-efficient vulcanization (semi-EV) has transformed soft-like NR phases into high elastic NR phases, at which small vulcanized NR phases acted as energy dissipating center that can bear higher applied load without chain slippage. The flexured and fractured surfaces of filled systems were investigated using scanning electron microscope (SEM) technique to determine particle sizes of NR phases and its toughening mechanism. The formation of more conductive pathways in the vulcanized filled systems was agreed by the XRD analysis. Vulcanized filled systems have higher cross-link density in which implied that vulcanized NR phases are resistant to chemical penetration and cannot be easily removed. [ABSTRACT FROM AUTHOR]