共聚低热膨胀聚酰亚胺薄膜的制备与表征

以4,4′-(六氟异丙烯)二酞酸酐(6FDA)为含氟二酐,4,4′-二氨基-2,2′-双三氟甲基联苯(TFMB)为含氟二胺,通过引入分子结构相对对称的刚性单体1,2,4,5-均苯四甲酸二酐(PMDA)进行共聚合成了5种含氟比例不同的透明聚酰亚胺薄膜,并对其性能进行了表征。分析表明:引入刚性单体共聚后薄膜的热稳定性和耐热性有所提高;薄膜的介电常数随着PMDA含量的上升而增加;共聚薄膜在可见光领域的透光率低于均聚薄膜;拉伸实验显示在添加少量PMDA后,薄膜的拉伸强度和弹性模量有所增大,但当PMDA含量过高时其力学性能反而下降;随着PMDA含量的增加,薄膜的热膨胀系数明显降低。

Preparation and characterization of low expansion transparent copolyimide films

Five transparent polyimide thin films with different proportions of1,2,4,5-,pyromellitic dianhydride (PMDA) were made by copolymerization of4,4′-(six fluoro isopropenyl) two phthalic anhydride (6FDA),4,4′- two amino -2,2′- double three trifluoromethyl biphenyl (TFMB) and PMDA, and their properties were characterized. The results show that thermal stability and heat resistance are increased after the introduction of rigid monomers;the dielectric constant of the films is increased with the increase of PMDA content;homopolymer film has higher light transmission rate than copolymer films in visible light;tensile test shows that adding a small amount of PMDA, the tensile strength and elastic modulus of the film are increased, but when the content of PMDA is higher than 40%, the mechanical properties are decreased;the coefficient of thermal expansion of the films are decreased obviously while PMDA content is increased.