Effects of high shear rate shearing on material structure and mechanical property of iPP/PC blends

Abstract

Polycarbonate (PC) and crystalline polymer, isotatic polypropylene (iPP), are extruded using a mechanical blending extruder and a reciprocated mechanism for shearing is designed to perform long term shearing at a high shear rate in the packing stage. The present work investigates the effects of high shear rate shearing on the orientation of the phase morphologies and mechanical properties. The experiment utilises the technologies of specimen preparation and observation to examine the change in phase morphology. Additionally, the mechanical properties of injection moulded specimens under different processing conditions are measured. Experimental results show that adding a little PC into the iPP matrix, less than around 20%, increases the tensile strength of specimens. The orientation of the phase is improved and most of the tensile strength of the blends is increased after shearing. The tensile strength of the shearing specimens with a PC content of <25% exceeds that of the normal specimens of pure iPP. A higher iPP content corresponds to a higher tensile strength after shearing. This investigation also considers the possibility of using iPP/PC blends in industrial applications, indicating that shearing is valuable in industrial applications when the PC content in iPP/PC blends is <25%.