含氟聚酰亚胺的辐射交联及其交联度的XPS表征

含氟聚酰亚胺(FPI)是一种耐高温、耐水解的新型聚酰亚胺。到目前为止,尚未见文献报道它的辐射交联。本文发现它能在高温辐射下交联,交联后的含氟聚酰亚胺的玻璃化转变温度以及高温力学性能有明显提高。本文还首次用XPS方法做了它的交联度表征。用XPS方法求得FPI的凝胶化剂量为50Mrad。     

Physical aging of thin 6FDA-based polyimide membranes containing carboxyl acid groups. Part I. Transport properties

The effect of molecular structure on the kinetics of physical aging of thin films (∼350 nm) formed from glassy 6FDA-based polyimides was investigated by tracking the changes in gas permeability (He, O₂ and N₂) at 35 °C for more than 2000 h. The structures studied included homopolymers of 6FDA with 6FpDA and with DAM plus copolymers where a portion of the latter two monomers was replaced with DABA to introduce carboxyl units into the structure for subsequent cross-linking studies. Over this period of aging, the oxygen permeability decreased by a factor of two for the polyimide containing the diamine 6FpDA and by a factor of five for the polyimide containing the diamine DAM. Introduction of DABA units accelerated the aging in the case of 6FpDA and slowed the aging in the case of DAM. Aging rate seems to correlate with the level of free volume of the polymer; the higher the free volume, the faster is the aging. Selectivity for all gas pairs increased upon aging but the rate is not simply explained by free volume alone because the difference in size of the two gas molecules is also reflected in the response to physical aging observed.