为了在尽量不影响其透光性的前提下解决含氟聚酰亚胺薄膜热膨胀系数(CTE)过大的问题,以4,4'-(六氟异丙烯)二酞酸酐(6FDA)、4,4'-二氨基-2,2'-双三氟甲基联苯(TFMB)和3,3',4,4'-联苯四羧酸二酐(BPDA)为原料,通过两步法合成了5种BPDA掺杂量分别为0、10％、20％、30％和40％的共聚PI薄膜,并采用红外光谱分析(IR)、热重分析(TGA)、热机械性能分析(TMA)等方法对其性能进行了表征.分析表明:共聚薄膜的热性能相比均聚薄膜有所提高;薄膜的介电常数与BPDA的含量成正比,而其在可见光领域的透光率与BPDA的含量成反比;在BPDA含量较低时,薄膜的拉伸强度和弹性模量随BPDA含量的增加而增大,但当BPDA摩尔分数超过30％时其力学性能开始降低;随着共聚单体含量的上升,薄膜的热膨胀系数大幅减小.%In order to minimize the coefficient of thermal expansion (CTE) of fluorinated polyimide film without reducing its transmittance, 5 kinds of Co-PI thin films whose BPDA content were 0％, 10％, 20％, 30％, and 40％ were prepared by copolymerization of 4, 4'- (six fluoro isopropenyl) two phthalic anhydride (6 FDA), 4, 4'-two amino-2, 2'-double three trifluoromethyl biphenyl (TFMB), and 3, 3', 4, 4'-two four biphenyl carboxylic acid anhydride (BPDA) through a two-step method. Properties of the films were characterized by methods such as Fourier transform infrared spectroscopy (IR), thermogravimetric analysis (TGA), and thermal mechanical analysis (TMA). Results show that compared with homopolymers, copolymer films had better thermal properties. The dielectric constants of films were directly proportional to the content of BPDA, while their transmittances in the visible light zone changed in the opposite way. Tensile test showed that the tensile strength and elastic modulus of the films increased with the increase of the content of BPDA, but when the content of BPDA was more than 30％, the mechanical properties began to decrease. With the increase of comonomer content, the thermal expansion coefficient of the film decreased greatly.
展开▼
