Molecular Weight Distribution of a Branched Epoxy Polymer: 1,4-Butanediol Diglycidyl Ether with Cis-1,2-Cyclohexanedicarboxylic Anhydride

摘要

Laser light scattering (LLS) and size exclusion chromatography (SEC) have been used to study the curing of an epoxy resin, 1,4-butanediol diglycidyl ether,with cis-1,2-cyclohexanedicarboxylic anhydride. During the curing process, the branched epoxy polymer product formed before its gelation threshold is soluble in either methyl ethyl ketone (MEK) or tetrahydrofuran (THF). LLS could be used successfully to determine the weight-average molecular weight (Mw) and to estimate the molecular weight distribution (MWD) of the branched epoxy polymer at each stage of the polymerization reaction before the gelation threshold. The MWDs obtained from LLS were compared with those determined by conventional SEC. From the comparison, we were able to develop a new absolute calibration procedure for SEC of specific branched polymers. For branched epoxy polymers before its gelation threshold, we were able to confirm the scaling behavior of the size distribution with a critical exponent Tau value of 2.1 plus 0.1. Reprints.