Mechanical properties and thermal properties of PMMA/EVA/Kenaf short fiber composites prepared by twin screw extruder and injection holding

Abstract

Poly (methyl methacrylate) (PMMA) composites with variation of kenaf short fiber (KSF) was prepared by using twin screw extruder and injection molding. The effect of ethylene vinyl acetate (EVA) on the toughness of PMMA/KSF composites was also investigated. The effect of injection temperature at plasticizing zone was investigated using the sample of PMMA/EVA (70/30) filled 10% weight KSF. It was found that tensile properties of composites at 230°C were higher than those at 220 °C such as tensile strength, Young’s modulus, elongation at break and tensile toughness. The temperature of 230 °C was selected for injection sample of KSF content and EVA content. The KSF content was varied from 0, 5, 10 and 15% filled PMMA/EVA (70/30). The mechanical properties results showed that impact energy, tensile strength, elongation at break and tensile toughness decreased with KSF content. In contrast, Young’s modulus of composites was increased with KSF loading. The addition of KSF also induces increment in the storage modulus, loss modulus of PMMA/EVA/KSF composites. For investigation of PMMA/EVA ratio (100/0, 80/20 and 70/30), the toughness of PMMA/EVA/KSF composites obtained from impact test showed that PMMA/EVA ratio of 80/20 better than 70/30 and 100/0. This was also in agreement with tensile toughness. EVA exhibited not only toughening effect but also plasticizing effect, which causes Young’s modulus, storage and loss modulus of PMMA/EVA/KSF composites lower than those of PMMA composites (without EVA). The presence of EVA also shifted the peak of tan δ of PMMA/EVA/KSF to higher temperature. The root effect originated from melting temperature of EVA around 120 °C which obtained from DSC results. The presence of KSF and EVA content also enhanced thermal stability of PMMA/EVA/KSF composites which obtained from TGA results.