Effect of injection velocity on the structure and mechanical properties of micro injection molded polycarbonate/poly(ethylene terephthalate) blends

A method of investigating the relationship between morphological evolution and mechanical properties of blends prepared by Micro injection moulding through regulating the process conditions was presented in this paper. The microstructure and microscopic mechanical properties of polycarbonate/poly (ethylene terephthalate) (PC/PET) microparts prepared by micro injection moulding were investigated with respect to the effects of the injection velocity. The PC/PET microparts exhibited typical skin-core morphology. Thickness of the skin layer is greater than that of the core layer near the gate of micropart. With an increase in the injection velocity, the core layer became thicker. It was detected that the PET microdomains were selectively located in the core layer in preference to the shear layer with high injection velocity. In addition, the degree of orientation for main chain and pendant group in the PC/PET molecular chains increased first and then decreased with an increase in the injection velocity. Nanoindentation testing showed that the modulus decreased along the flow direction and increased with an increase in the injection velocity, except at very high values. Among the different layers, the highly oriented shear layer had the highest indentation modulus. (C) 2017 Elsevier Ltd. All rights reserved.