The effect of long-term natural aging on the iPB-1 structure and the II – I phase transformation rate

Abstract

The long-term natural aging of isotactic polybutene-1 samples of different molecular weight has shown that the transformation rate from the initial phase II to the stable phase I significantly decreased after natural aging, ranging from 0 to 17 years. It was found that the total crystallinity decreased with aging time and a small amount of phase II remained untransformed for at least 17 years. The transformation rate of a lower molecular weight sample, DP 0400, was higher than the PB 0110 sample, even after repeated polymer melting of aged samples and their new melt crystallization. The major phenomenon of the iPB-1 aging is the change in a ratio of methyl/methylene functional groups; possibly because of a side chain splitting that reduces the geometric regularity of the molecular chain and consecutively slows down the proceeding phase transformation. © 2020