Physical and thermal properties of polypropylene/rice straw biocomposite foam

Abstract

Polymer foam biocomposites based on polypropylene/rice straw (PP/RS) were successfully prepared by using an extrusion foaming process. The compounding of PP and RS was performed in a twin-screw extruder which was blended with crosslinker; dicumyl peroxide (DCP), blowing agent; azodicarbonamide (AZ) and different compatibilizers; polypropylene maleic anhydride (PPMAH) and ULTRAPLASTTM TP10. Compatibilizers were utilised to improve poor interfacial interaction between hydrophilic rice straw and hydrophobic matrix polypropylene. The foam biocomposite was extruded at temperatures of 180, 190, 190 and 200 °C respectively, which set from the feeder until the die zone. Each sample has five different series of formulations. The density test, water absorption test and gel content test were conducted to study the physical properties of PP/RS biocomposite foam. The thermal properties were also investigated by using differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). Meanwhile, the morphologies of the biocomposite foams were observed through scanning electron microscopy (SEM). The incorporation of PPMAH or TP10 improved the compatibility and processability of PP/RS biocomposite foam. This formulation has produced a good cell structure, lower density of biocomposite, improved the water uptake resistance and exhibited the best crosslinking density.