立构规整性对PAN大分子天生缠结及溶解性的影响

Influences of Chain Stereoregularity on Inborn Entanglement and Solubility of Polyacrylonitrile

对各种立构规整性的聚丙烯腈(PAN)样品的大分子天生缠结和溶解性能进行研究发现,当立构规整性相同时,PAN样品随着分子量的增加,其天生缠结指数(EI)增加,溶解性降低;对于分子量和化学构造相近的样品,PAN样品随着分子链等规立构(mm)的含量增加,其EI降低,溶解性也降低.天生缠结指数与溶解性并不总是表现出一致性.

The effect of chain stereoregularity on inborn entanglement and solubility of polyacrylonitrile (PAN) was examined. The three PAN samples of various stereoregularity were prepared by three different ways, namely matrixanionic polymerization (MAP), radiation - induced radical polymerization and aqueous suspension radical polymerization. The inborn entanglement index (EI) is defined by (Mro - Mre)/Mro, where Mro and Mre are the measured apparent molecular weights ( Mr) of PAN before and after shear modification, and the triad tacticity was measured by IR spectroscopy. It is shown that under nearly the same chain stereoregularity, the value of EI increases with the increasing Mr, while, the solubility of PAN samples decrease with the increasing Mr, and that under nearly the same Mr, the value of EI and the solubility decrease with the increasing triad content (mm) in the PAN chain. The experimental results suggested that EI may not always consistent with solubility of PAN.