Study On Preparation Characterization And Flame Retardancy On Polycarbonate Of Carboxyl-Polysiloxane And Hydroxyl-Polysiloxane

Wide applications of polymer materials are driving the rapid development of flame retardants. As the technology of flame retardant developing to the direction of environmental protection, low toxicity and high efficiency, environment-friendly fire retardants have become one main research direction of flame retardant technology. Organic polysiloxane is just one of the ideal environmental-friendly flame retardants. The thermal degradation and combustion products of organic polysiloxane after introduced into the polymers are SiO2 and other silicon-containing compounds, which are almost environmentally friendly. Moreover, low concentration of smoke and toxic gas will be released during the combustion of silicon-containing polymers, and the propagation of flame is slow. So the application of organic polysiloxane in polymer flame retardants has attracted the researchers very much.The newly progress about organic polysiloxane, polycarbonate (PC) and the flame retardants uses reviewed in this dissertation were based on the investigation of a large amount of literatures. In the dissertation, two kinds of organic polysiloxane containing carboxyl and hydroxyl(POS-COOH, POS-OH) were also synthesized from methyldiethoxysilane (containing a certain amount of triethoxysilane), acrylic acid and allyl alcohol, some characterizations of these two organic polysiloxane's structure were investigated, too. In addition, two series of flame retardant PC hybrids prepared were based on PC, POS-COOH and POS-OH by melt blending method. The thermal stability, flame retardant properties of the hybrids, mechanical properties were investigated. The flame retardant mechanism of POS-COOH and POS-OH had been discussed in the paper in detail. The paper is mainly divided into some parts following:(1) Study on preparation and impact factors of OSI-COOH and OSI-OH.Two kinds of organic silicone intermediates containing carboxyl and hydroxyl(OSI-COOH, OSI-OH) were synthesized by hydrosilyation reaction, using methyldiethoxysilane (containing a certain amount of triethoxysilane), acrylic acid and allyl alcohol. Time, the impact of temperature and molar ratio of monomers on the yield were discussed, we obtained the most reasonable experimental conditions:for OSI-COOH, the molar ratio of Si-H and unsaturated compound was 1.2:1, the optimal reaction temperature was 85℃for 24 h; for OSI-OH, the molar ratio of Si-H and unsaturated compound was 2.0:1, the optimal reaction temperature was 90℃for 20 h, the yield were 97.86% and 95.48%.(2) Preparation and characterization of carboxyl-polysiloxane (POS-COOH) and hydroxyl-polysiloxane (POS-OH).Then POS-COOH and POS-OH were prepared by hydrolysis condensation reaction, using OSI-COOH and OSI-OH prepared by the reaction of the previous step, and the reactions were catalysted by sulfuric acid aqueous solution (containing 40-50% sulfuric acid) under 30-35℃for 1-2 hours, and the yield were 88.92% and 92.77%. The molecular structures of two were characterized by FTIR,29Si-NMR, SEM, TEM, XRD. We also use TGA to investigate thermal properties of them.(3) Study on preparation, flame retardancy, thermal property and mechanical properties of polycarbonate (PC) composite materials.POS-COOH (POS-OH) particles were well dispersed in the PC matrix and there was no chemical reaction between the POS-COOH (POS-OH) particles and PC matrix during the melt blending. The results of LOI and UL-94 test showed that POS-COOH and POS-OH played a flame-retardant effect well, LOI of the two kinds of composite materials were raised up to 32.3 and 31.1 and could pass UL-94 V1 test (3.2mm). The results of TGA showed that the addition of POS-COOH and POS-OH raised thermal stability of composite materials under high temperature. The initial decomposition temperatures of composite materials raised 43.5℃and 33.8℃; the temperatures decomposition rate raised 31.1℃and 30.6℃at maximum; POS-COOH and POS-OH also could enhance the char formation in high temperature to form stabile. The results of mechanical properties test showed that POS-COOH and POS-OH raised tensile strength and flexural strength, but reduced the izod impact strength of composite materials.