Mechanical and thermal properties of kenaf fiber and montmorillonite reinforced recycled polyethylene terephthalate/recycled polypropylene composites

Abstract

The feasibility of developing kenaf fiber (KF) reinforced recycled polyethylene terephthalate (rPET) and recycled polypropylene (rPP) with comparison to two different reinforcing fillers, KF and montmorillonite (MMT) reinforced rPET/rPP was studied. In addition, the compatibilizer of ethylene vinyl acetate grafted maleic anhydride (EVA-g-MA) at composition 0-10 phr was used. Composites were prepared using twin-screw extruder and followed by injection molding. The optimum blend ratio of rPET/rPP was observed at 90 wt% rPET and 10 wt% rPP. Thermogravimetric analysis data showed that thermal stability of uncompatibilized rPET/rPP blend with ratio of 90/10 had maximum degradation temperature at 399.3 oC. Differential scanning calorimetry data revealed that rPET/rPP blend had two melting temperatures. The incorporation of 5 phr EVA-g- MA improved tensile and impact strength of the blends. Besides, the maximum decomposition temperature of rPET/rPP blend also increased. Scanning electron microscopy (SEM) micrographs revealed that by adding EVA-g-MA, uniform particles sizes of rPP was observed, indicating an interaction between both of tertiary carbon of rPP and ester group of rPET with EVA-g-MA. The addition of KF into compatibilized blend decreased mechanical and thermal properties. The maximum value of tensile and impact strength of the blends was obtained at 43.9 MPa and 43.4 J/m respectively, when 1 phr of MMT was added into the rPET/EVA-g-MA/rPP/KF blend. However, SEM micrograph showed that the addition of 4 phr MMT led to filler agglomeration which decreased tensile strength of rPET/EVA-g- MA/rPP/KF/MMT composite.