Search

This work proposes a new understanding of the side effect of mineral fillers in polymer compounding that caused different levels of thermo‐mechanical degradation (TMD) during extrusion. Three mineral fillers, silica (random shape), kaolin (platy), and wollastonite (needle‐like), were selected and compounded with the polypropylene‐ethylene copolymer (PPcoE) using a twin‐screw extruder. Their influences on the TMD of PPcoE were examined by checking the substances in the extrudates using Fourier transform infrared spectroscopy. The built‐up shear stress causing by mineral filler in PPcoE composite (Δτcom) as the root of TMD was measured and estimated using capillary rheometer. In this study, TMD is classified as two levels: chain scission and oxidization. These fillers were found to accelerate the TMD mechanism and generate the oxidised products during extrusion. The silica filler caused the highest Δτcom, the lowest tensile strength, and elongation at break of PPcoE composites. The kaolin filler gave the most potent accelerating effect on oxidization, resulted in the formation of tertiary alcohol, and the highest ester contents in PPcoE composites; although, its composite had the lowest Δτcom among the fillers. Lastly, wollastonite filler provided higher Δτcom than kaolin composite, the second‐highest formation of alkene products, yet better retention in elongation at break compared to the silica‐filled PPcoE composite. In general, the side effect of mineral filler on TMD was a larger particle size always comes with higher chain scission, simpler particle morphology gives a smoother built‐up shear stress and minimizes TMD, and filler having hydroxyl groups catalyzes the oxidization TMD. [ABSTRACT FROM AUTHOR]

The recycled high density polyethylene/ethylene vinyl acetate (RHDPE/EVA) blend was prepared by using Brabender Plasticoder mixer. Taro powder (TP) filler was added to produce RHDPE/EVA/TP composite. The effect of TP filler and different modifications approached: by treatment of TP filler with methyl methacrylate (MMA); by addition of commercial compatibiliser of polyethylene grafted maleic anhydride (PE-g-MAH); and by addition of hybrid compatibiliser of caprolactam-maleic anhydride (CLMAH) were studied. Tensile properties, swelling behaviour, morphology, and thermal properties were also investigated. Findings indicated that the addition of TP filler led to the reduction in tensile strength and elongation at break while showing increment in modulus of elasticity. Upon modifications, the tensile strength and modulus of elasticity increased while the elongation at break decreased slightly. The composites exhibited an increased chemical uptake resulting in increased percentage mass swell once TP filler was added and after modification of the composites. The usage of compatibiliser and treatment of filler enhanced interfacial adhesion of matrix and filler with improvement in dispersion of filler as evidenced by scanning electron microscopy (SEM). [ABSTRACT FROM AUTHOR]

The effect of the chemical modification of wood fibre (WF) using salicylic acid/ethanol on the tensile properties, water absorption, thermal degradation and morphology of recycled high density polyethylene/WF (rHDPE/WF) composites was studied. Both of the composites: rHDPE/WF and rHDPE/WFM (modified with salicylic acid and ethanol) were prepared using a Brabender Plasticorder at 160°C with a rotor speed of 50 rpm. The results indicate that the rHDPE/WFM composite has a greater tensile strength, a higher modulus of elasticity, greater thermal stability, greater resistance to water absorption and a lower elongation at break than the rHDPE/WF composite. SEM micrographs show that better interfacial adhesion occurs between the WF phase modified with salicylic acid and ethanol (WFM) and the rHDPE phase in the rHDPE/WFM composite. [ABSTRACT FROM AUTHOR]