Study On The Blended Modification Of Polycarbonate And Highly Branched Polystyrene

In the dissertation, highly branched polystyrene (HBPS) was synthesized by the atom transfer radical polymerization, afterwards, HBPS that has the characteristic of the low viscosity was added to polycarbonate that has the characteristic of the high viscosity, consequently, the two kinds of polymers were blended by the method of melt blending. The series of properties about PC/HBPS blends were studied and discussed, including mechanical properties, morphological structure, thermal properties, compatibility, rheological properties and mechanical relaxation. The main contents are as following:1. Synthesis and characterization of HBPS.(1) Three kinds of highly branched polystyrene had been synthesized by the atom transfer radical polymerization, and they were named HBPS-1, HBPS-2 and HBPS-3.(2)Their structures were characterized by the FTIR, ¹H NMR and GPC. The degree of branching, molecular weights and molecular weights distribution of HBPS-1, HBPS-2 and HBPS-3 are increased in turn. The glass transition temperature(Tg) of HBPS-1, HBPS-2 and HBPS-3 were studied by DSC. Their glass transition temperatures are lower than that of PS and decreased gradually according to the order of HBPS-1, HBPS-2 and HBPS-3.The decomposed temperature(Td) and half decomposed temperature(T₅₀) of HBPS-1, HBPS-2 and HBPS-3 were studied by TGA. The decomposed temperature and half decomposed temperature of HBPS-1, HBPS-2 and HBPS-3 are higher than that of PS. According to the order of HBPS-1, HBPS-2 and HBPS-3, their decomposed temperature is decreased gradually and their half decomposed temperatures have not almost difference.2. Preparation, mechanical properties and morphological structure of PC/HBPS blends. (1)Twelve kinds of blends were prepared by the way of mixed melt blending(2)The izod impact strength, tensile strength and tensile elastic modulus of all the blends were tested. In the matrix PC, when the content of HBPS is less than 2.0ms%, the addition of HBPS has not influence the excellent mechanical properties of PC. when the content of HBPS is 0.5ms%,1.0ms%, the izod impact strength of PC/HBPS blends is higher than that of pure PC.(3)Morphological structure of PC/HBPS blends was studied by SEM. In the SEM photographs, the morphological structure of PC/HBPS blends is the two-phase systems. Especially, for PC/1.0HBPS-1,PC/1.0HBPS-2 and PC/0.5HBPS-3 blends, the ruptured surfaces are accidented and have many honeycomb structure, the above phenomenon validate...