Study On High-Pressure Crystallization Behaviors Of Aromatic Polyester, Polyester Blends And Polyether

The Study on the crystallization behaviors of an engineering plastics with general high-performance, such as bisphenol-A polycarbonate (PC), poly (ethylene terephthalate) / bisphenol-A polycarbonate (PET/PC) blends and poly (p-phenylene sulfide), can enlarge its application area and deepen the understanding about the nature of polymer crystallization. In this dissertation, the high-pressure crystallization behaviors of PC, PET/PC blends and PPS were investigated, including melt crystallization of PC, crystallization of PC induced by dioctyl phthalate (DOP), effect of preparation conditions of the starting materials on the thickening growth of the polyester extended-chain crystals in PET/PC blends, analysis of the large polymer extended-chain single crystals and observation of the novel crystal morphologies formed in the PET/PC blend samples, and growth of PPS extended-chain crystals. A large quantity of valuable data and results were obtained, which is of great importance to develop the theory for the designing and controlling of the properties of the crystallizable aromatic polymers. The main work and conclusions were listed as follows:1) PC extended-chain crystals with C-axis thickness exceeding 15μm were cultured through the melt crystallization. Other characteristic morphologies formed at high pressure, i. e. spherulites, cylindrulites and lath crystals, were also presented with the scanning electron microscopy (SEM) measurements. This study suggests that high-crystallinity PC samples with a wide variety of microstructures can be obtained under high pressure by a double-heat treatment, i. e. low-temperature crystallization and subsequent high-temperature annealing.2) The crystallization of PC in the PC/DOP blends could be greatly hastened by the high-pressure treatment, which resulted in a wide variety of morphologies of PC crystals at the same time, including spherulites, spatial dendrites, crystalbars, platelets and regular polygonal crystals of different characteristics. The SEM measurements revealed a granular substructure of the lamellae in a low-crystallinity sample, which indicated that the crystallization of PC in the multiphase system was compatible with the model developed by Strobl. This study also suggested that extended-chain crystals could not be obtained through the crystallization of PC induced by DOP under high pressure.3) Some novel stereo-open spherulitic structures, i. e. peony-like spherulite,...