【作者】 赵炜；

【导师】 顾宜；

【作者基本信息】 四川大学 ， 材料学， 2005， 硕士

【摘要】 本文以3,3’,4,4’-二苯酮四羧酸二酐(BTDA)为二酐类单体,与二胺单体:间苯二胺(m-PDA)、4,4’-二苯醚二胺(ODA)、对苯二胺(p-PDA)和4,4’-联苯二胺(BZD)在N-甲基吡咯烷酮(NMP)中合成了四种不同主链结构的聚酰胺酸。并以这些聚酰胺酸溶液为基础,采用不同的工艺条件进行热酰亚胺化,制备了相应的聚酰亚胺。通过WAXD,PLM,SEM等表征手段,研究了分子主链结构对聚酰亚胺形成聚集态有序性结构的能力、结晶的形貌、结晶度的影响,以及不同的热酰亚胺化工艺对有序性结构的形成过程、结晶形貌的影响。 采用了三种热酰亚胺化工艺对BTDA-m-PDA、BTDA-ODA、BTDA-p-PDA三个体系进行了研究:一步法溶液热酰亚胺化;涂膜快速升温热酰亚胺化;两步法涂膜热酰亚胺化,再进行溶胀,高温处理。通过采用一步法溶液酰亚胺化制备了三个体系的半晶性粉末;采用涂膜快速升温热酰亚胺化工艺获得了BTDA-m-PDA体系的环带球晶,BTDA-ODA体系的不完善的球晶,而BTDA-p-PDA体系在该工艺条件下不能形成有序性聚集态结构;采用两步法涂膜热酰亚胺化,再进行溶胀,高温处理的工艺制备了三个体系的具有低有序性的聚酰亚胺薄膜。对通过一步法溶液热酰亚胺化获得的半晶型粉末的研究表明,所研究的三种酮酐型聚酰亚胺体系都可以形成晶体结构,三个体系按BTDA-m-PDA、BTDA-ODA、BTDA-p-PDA的顺序结晶度分别为:52.2%,40.0%,64.8%。涂膜快速升温热酰亚胺化的研究表明,三个体系聚酰亚胺形成有序性结构的趋势由强到弱的顺序为:BTDA-m-PDA、BTDA-ODA、BTDA-p-PDA。而通过两步法涂膜热酰亚胺化,再进行溶胀,高温处理的工艺制备的低有序性的聚酰亚胺薄膜与无定型结构的薄膜相比,具有更高的拉伸强度和拉伸模量,低的断裂伸长率。 对BTDA-BZD体系研究表明,在通常的两步法酰亚胺化工艺条件下,其结晶结构的形成分成两个阶段进行。首先,在经过100℃/1h处理以后,该体系的聚酰更多还原

【Abstract】 Four types of poly(amic acid)s were synthesized using 3,3’ ,4,4’ -benzophenone tetracarboxylic dianhydride (BTDA) as dianhydride monomer and meta-phenylene diamine (m-PDA), para-phenylene diamine (p-PDA), 4,4’ -oxydianiline (ODA), benzidine (BZD) as diamine monomers respectively. Based on these poly(amic acid)s, four type of corresponding polyimides were prepared through different imidization procedures. The effects of macromolecular chain on the formation of aggregation structures, crystallinity, and morphology were studied using WAXD, PLM, SEM, etc. Also, the effects of imidization procedures on the formation of aggregation structures were studied as well.Three different imidization procedures were used to study BTDA-m-PDA, BTDA-ODA and BTDA-p-PDA systems, such as: imidization in PAA solution at 180°C (procedure 1) ; imidization of PAA coating film at high temperature (procedure 2); swell of the PI films and then processed at 300°C (procedure 3). Semicrystalline polyimide powders were prepared by procedure 1 for all three types of polyimides studied. By using procedure 2, banded spherulite was obtained for BTDA-m-PDA system, and underdeveloped spherulite was observed for BTDA-ODA system. For BTDA-p-PDA system imidized through procedure 2, no ordered aggregation structure was observed. For procedure 3, polyimide films with low-order aggregation structure were prepared for all the systems studied. The semicrystailine polyimide powders showed that all of the three polyimides could form crystal structure and have a crystallinity of 52.2%, 40.0%,64. 8% for system BTDA-m-PDA,BTDA-ODA and BTDA-p-PDA, respectively. Study on polyimides prepared through procedure 2 demonstrated that the ability to form order aggregation structure of these polyimides decreased in an order of BTDA-m-PDA, BTDA-ODA, BTDA-p-PDA. Compared with amorphous polyimide films, the films which were prepared by prepared by procedure 3 and bared low-order aggregation structure had a higher tensile strength and modulus, meanwhile, a lower elongation at break.Study on BTDA-BZD system showed that the process of crystallization consisted of two steps. Firstly, after held in 100°C oven for lh, the poly(amic acid) of BTDA-BZD formed a low-order aggregation structure. When the time in 100 °C oven was prolonged to 7h, the order of the aggregation structure disappeared. Secondly, after processed for 200 "C/lh, the molecular chains formed an order aggregation structure, and the process of 300°C/lh strengthened the order of aggregation structure. During the preparation of BTDA-BZD polyimide by two-step method, these steps of crystallization would affect the aggregation structure of final polyimide. The result of copolymerization illustrated that the polyimides had an order aggregation structure for alternative copolymer and irregular copolymer, but the order of the aggregation structure of polyimide copolymers was not so good as that of BTDA-BZD polyimide. BTDA-BZD polyimide had a lower tensile strength and elongation at break than those of polyimide copolymers, but a higher tensile modulus. There was no difference between the tensile properties of alternative copolymer and irregular copolymer.At last, computer molecular modeling was adopted to study the differences between the ability to crystallize and order of the aggregation structure of polyimides with different backbones. Simulation of conformation and energy needed to change conformation of single polyimide chains offered a kinetic reference to judge the ability of different polyimides to crystallize. Simulation of 3-D periodic boundary,from a thermodynamic point of view, explained the differences between the order of the aggregation structure of different polyimides.更多还原