老化对聚(1-三甲基硅基-1-丙炔)气体渗透性能的影响

采用溶液浇铸法,制备了厚度为50～202μm的聚(1-三甲基硅基-1-丙炔)(PTMSP)膜,研究了膜厚度、储存温度以及储存气氛对其气体渗透性能的影响。在室温下储存时,PTMSP膜发生物理老化,气体渗透系数先是迅速下降,然后缓慢降低并趋向平稳。在空气气氛中的下降速率要略大于在N2气气氛中。气体渗透系数的下降速率随膜厚度的减小而增大。在高温(100℃)空气气氛中,受物理及化学老化的共同作用,PTMSP膜气体渗透系数的下降速率进一步增大,IR谱图表明,聚合物氧化生成了CO等极性基团。随储存时间的延长,溶解度系数基本不变,扩散系数的下降是导致气体渗透系数下降的主要原因,这与聚合物体积松弛和(或)致密化及极性基团的形成所造成的自由体积的减小紧密相关。

Effect of Aging on the Gas Permeation Properties of Poly (1-trimethylsilyl-1-propyne)

Poly(1-trimethylsilyl-1-propyne)(PTMSP) membranes were prepared by a solution-casting method in thickness ranging from 50 μm to 202 μm to study the effect of aging on their gas permeabilities. These membranes stored at room temperature display substantial decreases in gas permeability with time because of physical aging. The gas permeability decreased rapidly at first, and a slower, more gradual decrease and then almost leveled off was observed. PTMSP membrane stored in air exhibited slightly larger permeability decrement than that stored in N2. The decrease rate of gas permeability increased with the decrease of membrane thickness, and it decreased much more when the PTMSP membrane aged at high temperature of 100 ℃ in air, which is due to both physical aging and chemical aging. IR spectrum of the membrane indicates that storage of PTMSP at high temperature in air results in oxidation of the polymer with formation of C=O groups. The gas permeability coefficient(P) of the membrane was inspected in more detail by determining the gas diffusion coefficient(D) and gas solubility coefficient(S). The S value hardly changed during storage, whereas the D value decreased with aging, which is responsible for the decrease of gas permeability. The decrease of D can be explained by the elimination of fractional free volume due to the volume relaxation and/or densification and the formation of polar groups in the polymer.