【作者】 王伟平；

【导师】 杨蕾；

【作者基本信息】 哈尔滨工业大学 ， 化学， 2018， 硕士

【摘要】 聚对苯撑苯并双噁唑(PBO)纤维以其卓越的机械性能、化学稳定性和阻燃隔热性能广泛的应用在社会生产生活的各个领域,其中包括军事领域中复合材料的增强体部分,高温条件下的耐热材料以及发动机上的隔热材料等。但是,PBO易紫外老化降解的问题,严重限制了其在户外或太空环境下的应用。本论文以提高PBO的耐紫外光老化降解为目的,通过α-TDMACu Pc与PBO聚合物的原位共聚反应,制备出PBO-α-TDMACu Pc纤维,在确保加入的α-TDMACu Pc不影响PBO本体性能的前提下,能够改善PBO的易紫外老化降解问题。首先确定了α-TDMACu Pc与PBO聚合物的最佳共聚温度为140℃,制备了PBO及一系列不同α-TDMACu Pc含量的改性纤维,为了研究α-TDMACu Pc的加入对PBO本体性能的影响,对纤维进行特性粘度和拉伸强度的表征,结果显示改性纤维的粘度和强度随α-TDMACu Pc含量增加呈现先增大后减小的趋势;为了研究α-TDMACu Pc对PBO分子结构和表面元素的影响,利用FT-IR、UV-Vis分析,证明α-TDMACu Pc聚合到PBO分子链中,通过XPS对纤维表面元素分析,发现改性纤维中C、N元素含量高于PBO。其次研究了α-TDMACu Pc对PBO耐紫外老化性能的提高,对老化后的纤维进行特性粘度和强度分析,结果显示紫外老化480h后PBO-2.0wt%α-TDMACu Pc纤维的特性粘度比PBO提高了130%,拉伸强度提高了55%;对老化后的纤维进行表面形貌分析和晶面结构分析发现α-TDMACu Pc的含量越多,老化后纤维的表面破坏程度越弱,α-TDMACu Pc的加入保护了纤维晶体结构受紫外光的破坏。对老化后的纤维进行TG、DTG测试,分析结果发现紫外老化480h后改性纤维的初始分解温度提高了40℃,最大分解温度提高了55℃。最后研究了PBO的老化降解动力学行为,发现其老化降解符合一级反应动力学方程,分别求出了30℃、50℃、70℃和90℃的老化降解速率k,并且结果显示PBO的老化降解速率随温度升高而加快,利用Arrhenius公式求出了纤维的老化活化能Ea为9.22k J/mol。通过实验分析发现α-TDMACu Pc是通过高效能量耗散无辐射机理(分子内氢键的质子转移)完成紫外光能量的吸收及释放过程。更多还原

【Abstract】 Poly-p-phenylene benzobisoxazole(PBO)fiber is widely used in various fields of social production and life for its excellent mechanical properties,chemical stability,and flame retardant and thermal insulation properties.These include reinforced parts of composite materials in the military field,heat-resistant materials under high-temperature conditions,and thermal insulation materials on engines.However,the problem of UV degradation and degradation of PBO fiber severely limits its application in outdoor or space environments.In this paper,PBO-α-TDMACu Pc fibers were prepared by in-situ copolymerization of α-TDMACu Pc with PBO polymer for the purpose of improving the UV degradation resistance of PBO fibers.To ensure that the added α-TDMACu Pc does not affect the bulk properties of the PBO fiber,it can improve the UV degradation and degradation of the PBO fiber.First,the optimal copolymerization temperature of α-TDMACu Pc and PBO polymer was determined to be 140℃.PBO fibers and a series of modified fibers with different contents of α-TDMACu Pc were prepared.In order to study the effect of α-TDMACu Pc addition on the bulk properties of PBO fibers,the intrinsic viscosity and tensile strength of the fibers were characterized.The results showed that the viscosity and strength of the modified fibers increased first and then decreased with increasing α-TDMACu Pc content.In order to study the effect of α-TDMACu Pc on the molecular structure and surface elements of PBO,using FT-IR and UV-Vis analysis,it was proved that α-TDMACu Pc was polymerized into the PBO molecular chain.Through XPS analysis of the fiber surface elements,it was found that the content of C and N in the modified fiber was higher than that of PBO fiber.Second,in order to study the effect of α-TDMACu Pc on the UV aging resistance of PBO fiber,the intrinsic viscosity and strength of the aged fiber were analyzed.The results showed that the intrinsic viscosity of PBO-2.0wt% α-TDMACu Pc fiber was increased by 130% and the tensile strength increased by 55% compared with PBO fiber after 480 h UV aging.The surface morphology analysis and crystal surface structure analysis of the aged fiber shows that the more α-TDMACu Pc content,the weaker the surface damage of the fiber after aging,the addition of α-TDMACu Pc protects the fiber crystal structure from ultraviolet light damage..The TG and DTG tests were performed on the aged fibers.The results showed that the initial decomposition temperature of the modified fibers increased by 40℃ after 480 hours of UV aging,and the maximum decomposition temperature increased by 55℃.Finally,the aging degradation kinetics behavior of PBO was studied and its aging degradation kinetics equation of composite first-order reaction was found.The degradation degradation rate k at 30℃,50℃,70℃ and 90℃ was obtained.The results show that the aging degradation rate of PBO fiber accelerates with the increase of temperature,and the aging activation energy Ea of the fiber is obtained by the Arrhenius formula.Through experimental analysis,it was found that α-TDMACu Pc absorbs and releases UV energy using a high-efficiency energy-dissipation mechanism without radiation(proton transfer in intramolecular hydrogen bonding).更多还原