分别采用均苯四甲酸二酐(PMDA)和氢化均苯四甲酸二酐(HPMDA)与4,4'-二氨基二苯醚(ODA)通过两步法制备了两种聚酰亚胺(PI)薄膜。比较了两种PI薄膜的物理化学性质,包括树脂的特性粘度,薄膜的耐热稳定性以及光学透明性等。结果表明,HPMDA-ODA薄膜在可见光区具有优良的透明性,450 nm处的透过率超过80%。该薄膜的折光指数为1.598 6,双折射接近0。薄膜的玻璃化转变温度为339.6℃,5%失重温度为451.9℃,氮气中750℃时的残余重量百分数为37.2%。
Two polyimide (PI) films were prepared by reacting the diamine 4, 4'-oxydianiline (0DA) with two dianhydrides, pyromellitic anhydride (PMDA) and hydrogenated pyromellitic anhydride (HPMDA), respectively, via a two-step polymerization procedure. The physical and chemical properties, including inherent viscosities, thermal stability, and optical transparency were investigated and compared. The results show that the HPMDA-ODA film have good optical transparency with the transmittance of higher than 80% at 450 nm, refractive index of 1. 598 6, and birefringence of near 0. In addition, the film have good thermal stability with the glass transition temperature of 339.6℃, 5% weight loss temperature of 451.9℃, and residual weight of 37.2% at 750 ℃ in nitrogen atmosphere.