【作者】 陈友财；

【导师】 周文君；

【作者基本信息】 杭州师范大学 ， 应用化学， 2012， 硕士

【摘要】 随着现代科学技术的发展,高分子材料在越来越多的领域得以广泛的应用。其中的聚碳酸酯(PC)因具有良好的透明性,较好的机械强度、耐热性能、耐紫外辐射及电绝缘等综合性能,用途更为广泛。随着电子、电气、建筑、汽车等领域对PC需求的日益扩大,对PC的阻燃性能、综合性能以及环境保护的要求也越来越高。因此迫切需要开发无卤高效的阻燃剂或复配阻燃体系对PC实施阻燃处理以满足在相关领域的应用要求。本文采用水解缩合法制备了环保无卤的聚铝硅氧烷阻燃剂,并将其应用于PC的阻燃处理,研究内容主要有以下三个方面：聚铝硅氧烷阻燃剂的制备及其阻燃性能；聚铝硅氧烷阻燃剂对PC物理性能的影响；纳米Si02对PC／聚铝硅氧烷阻燃材料性能的影响。以二苯基二甲氧基硅烷(DDS)、二甲基二甲氧基硅烷(DMM)等烷氧基硅烷和异丙醇铝(MSDS)为原料,采用水解缩合法合成了一种新型的聚铝硅氧烷阻燃剂。应用极限氧指数(LOI)法和锥形量热仪分析了聚铝硅氧烷对PC的阻燃作用。聚铝硅氧烷能明显提高PC的LOI,聚铝硅氧烷的结构对其阻燃性能影响较大,侧链中Ph/Me为6：4,R/Si为1.2的聚铝硅氧烷的阻燃效果最好,在PC中添加5%该聚铝硅氧烷可使PC的LOI从25.5%提高到30.4%。同时聚铝硅氧烷可使PC的最大热降解速率降低,800℃残炭率显著提高,PC/聚铝硅氧烷阻燃材料的800℃残炭率大约比纯PC高30-45%,表明聚铝硅氧烷在PC材料中具有降低降解速率,促进成炭的作用,尤其是Si-0链具有支链结构的R/Si=1.2的聚铝硅氧烷,这种促进成炭的作用更加显著。在燃烧过程中,聚铝硅氧烷会迁移到PC表面,与PC的降解产物发生相互作用,产生交联结构,Si和Al积聚在材料表面形成富含Si、Al的绝缘炭层,完全燃烧时阻燃PC形成了均匀、致密的炭层,正是这一富含Si、Al的致密炭层起到了良好绝缘保护层的作用,抑制了材料进一步降解,有效阻碍了可燃性气体的产生及向燃烧区的传递,从而有效地改善了PC的阻燃性能。锥形量热仪测试结果表明,在PC中添加聚铝硅氧烷阻燃剂可以延长PC的点燃时间,有效降低PC燃烧过程中产生的烟、热及CO、CO2等有害气体,显著提高了火灾性能指数,缓和整个燃烧过程,保证热量与外界环境及时传递,减少了火灾的危害。聚铝硅氧烷阻燃PC材料(聚铝硅氧烷的添加量为5WT%)的拉伸强度在55.5MPa-58.6MPa之间,与纯PC的拉伸强度55MPa相比有明显提高。PC的弯曲强度、冲击强度分别为86MPa.16KJ/m2,PC/聚铝硅氧烷的弯曲强度在84MPa-89MPa之间,聚铝硅氧烷对PC的弯曲强度影响较小,聚铝硅氧烷阻燃PC材料的冲击强度比PC提高了15-30%。由此可见,聚铝硅氧烷对PC力学性能的影响,总体上,不仅没有降低,反而有所提高。为获得阻燃性能和综合性能更加优良的阻燃PC材料,从自制的聚铝硅氧烷阻燃剂中筛选出阻燃性能优良的聚铝硅氧烷阻燃剂与PC、纳米Si02共混制得阻燃PC材料,研究该复合材料的阻燃性能和力学性能的变化。结果表明,纳米Si02对PC／聚铝硅氧烷阻燃材料的LOI影响很小,但Si02可使PC／聚铝硅氧烷的热释放速率降低。随着Si02含量的增加,阻燃PC材料的力学性能先增后降,添加适量的纳米Si02可使PC/聚铝硅氧烷阻燃材料的拉伸强度和冲击强度明显提高。纳米Si02对PC/聚铝硅氧烷的冲击强度的影响更为显著,当Si02含量为1WT%时达到最大值,比不含Si02的PC／聚铝硅氧烷的冲击强度提高了48%。更多还原

【Abstract】 With the development of modern science and technology, the polymer materials are widely used in various industries. The polycarbonate (PC), as a major kind of polymers has increasingly applications in those industries because of its superior properties such as good transparency, strong mechanical strength, good heat resistance, good anti-ultraviolet radiation and electrical insulation features. With the growing demand for the PC in the filed of electron, electric, building, automobile and so on, the requirements of its flame retardant property, comprehensive performance and environmentally-friendly features become higher and higher. It is highly needed to develop an efficient halogen-free flame retardant for fire-retardant treatment of PC to meet the requirements in the related fields. In this research we use co-hydrolysis condensation to prepare environmentally friendly halogen-free polyaluminosiloxane flame retardants, and apply it to the PC for its fire-retardant treatments. The research focus on the following three aspects:the preparation of the polyaluminosiloxane and the measuring of its flame retardant properties; the impacts on PC physical properties when the polyaluminosiloxane is added into the PC; the effects of the nano-SiO2on properties of the PC/polyaluminosiloxane.Novel polyaluminosiloxane flame retardants were synthesized through co-hydrolysis condensation reaction using diphenyldimethoxysilicone (PTMS), dimethyldimethoxysilane (DMPS) and aluminum isopropoxide as the raw materials. The flame retardant action of polyaluminosiloxane on PC was analyzed by limiting oxygen index (LOI) method and the cone calorimeter. The presence of the polyaluminosiloxane can significantly improve LOI of PC and the structure of polyaluminosiloxane affects its flame retardancy greaterly. It is found that when the Ph/Me ratio is6:4, and the R/Si is1:2in the branched chain, the polyaluminosiloxane reaches its highest flame retardancy. Adding5%of this polyaluminosiloxane into the PC, the LOI of the PC increased from25.5%to30.4%. The presence of the polyaluminosiloxane in the PC can reduce PC’s maximum thermal degradation rate, and increase its800℃carbon residue significantly. The800℃carbon residue of PC/polyaluminosiloxane system is30-45%higher than that of the pure PC, showing that the polyaluminosiloxane in PC reduced the degradation rate of the blends, and promoted the formation of the carbon layers, especially for the polyaluminosiloxane with1.2Si-O ratio in its branched chain. In the combustion process, polyaluminosiloxane will migrate to the PC surface, and PC degradation product interaction occurs, causing crosslinking structure. Si and Al accumulate in the material surface and form insulation carbon layer which is rich in Si、Al. When it is complete combustion, flame retardant PC forms a uniform, dense carbon layer, which acts as good insulating protection layer effects to inhibite material further degradation, effectively prevent the flammable gas produced and transfer to the combustion zone. Thereby it effectively improves the flame retardancy of PC. The cone calorimeter test results show that adding polyaluminosiloxane flame retardant in PC can prolong PC ignition time, effectively reduce smoke, heat and CO, CO2and other harmful gases generating in the burning process. Besides, it significantly improves the fire performance index, mitigates the whole combustion process, ensure the timely transmission of heat to the external environment, and reduce fire hazard.The tensile strength of the polyaluminosiloxane flame retardant PC (5WT%polyaluminosiloxane) is55.5-58.6MPa, while the tensile strength of the pure PC is55MPa. The presence of the polyaluminosiloxane improved the tensile strength of the PC. The flexural strength and impact strength of the pure PC are86MPa and16KJ/m2respectively, and the flexural strength of the PC/polyaluminosiloxane system is84MPa-89MPa. The effect of polyaluminosiloxane on the flexural strength of the PC is slight. The impact strength of the polyaluminumsiloxane retardant PC is15%to30%higher then that of the pure PC. Thus, on the whole, the effect of the polyaluminosiloxane on mechanical properties of the PC is not reduced but increased.In order to obtain flame retardant PC materials with more excellent flame retardant performance and comprehensive performance, a high performance flame retardant was screened out from the prepared polyaluminumsiloxanes. The polyaluminumsiloxane was then mixed with SiO2nanoparticles and PC to prepare the PC blends. The flame retardancy and the mechanical properties of these blends were investigated. The results show that the presence of the SiO2nanoparticles in the PC/polyaluminosiloxane has a little effect on its LOI value. However, the presence of the SiO2can reduce the heat release rate, and then reduces the fire hazard of the PC/polyaluminosiloxane. When increasing the SiO2content, the mechanical properties of flame-retardant PC material is firstly increased and then drop, adding an appropriate amount of nano-SiO2can improve obviously the tensile strength and impact strength of PC/polyaluminosiloxane flame retardant material. The nano-SiO2has a more significant influence on the impact strength of the PC/polyaluminumsiloxane. When the content of SiO2is1WT%, the influence reaches to the maximum value, and the impact strength is increased by48%than PC/polyaluminosiloxane without SiO2.更多还原