Effect of compatibilizer and coupling agent on properties of recycled high density polyethylene/ ethylene vinyl acetate / eggshell powder composites

The composites of recycled high density polyethylene (rHDPE)/ethylene vinyl acetate (EV A)/eggshell powder (ESP) were studied. The materials were mixed by using Brabender Plasticorder at 160 °C with rotor speed of 50 rpm. The effect of ESP loading, various types of compatibilizers, and coupling agent on mechanical properties, water absorption properties, morphological properties, thermal properties, spectroscopy infrared and XRD characterization of rHDPE/EV A/ESP composites were investigated. The various types of compatibilizer used in this study were maleic anhydride (MAH), poly (vinyl chloride)maleic anhydride (PVC-MAH), and benzyl urea (BU), while 3-aminopropyl-triethoxysilane (APTES) was used as coupling agent for filler modification. The addition of ESP filler to the composites has reduced the tensile strength and elongation at break, but increased the Young's modulus of the composites. The tensile-fractured surface morphology of the composites had shown that as the filler loading is increased, the filler tend to form agglomeration. The equilibrium water absorption of the composites was increased as the filler loading increased, while the thermal study by DSC and TGA shows that the addition of filler did not significantly affect the melting points and reduced the crystallinity of the composites, while increase the thermal decomposition temperature. XRD analysis revealed that the addition of filler loading has increased at 5 to 15 phr filler loading, but reduced at higher loading. Meanwhile the crystal orientation ratio was found decreased with the increased filler loading. The addition of compatibilizers and coupling agent was found to improve the tensile strength and the Young's modulus ofthe rHDPE/EVA/ESP composites, however reduced their elongation at break. The tensile-fractured surface morphology study indicated that the addition of compatibilizer and filler modification by coupling agent was found to improve the adhesion in the composites by the reduced filler detachment and the number of gaps. The resistance to water absorption of the composites also seems improved by the presence of compatibilizer and the filler modification with the coupling agent. The melting points of the composites did not significantly affect by the addition of compatibilizer while increased the percentage of crystallinity of the composites. However, the filler modification by the coupling agent was found to reduce the percentage of crystallinity of the rHDPE/EV A/ESP composites. The thermogravimetric analysis shows that the presence of compatibilizer and coupling agent has increased the thermal resistance of the composites at temperature range of 400-500 °C, however at higher temperature the thermal stability of the composites was deteriorated by the low residual mass than the untreated composites.