Relation between Molecular Conformation and Birefringence of Common Olefinic and Vinyl Polymers.

Abstract

The chain conformations of polyethylene (PE), polypropylene (PP), poly(vinyl chloride) (PVC), poly styrene (PS), and poly(methyl methacrylate) (PMMA) were analyzed by MM2(91) in which oligomeric model com pounds composed of several repeating units were used as the initial structures. The optimized steric structures of the model compounds were found to correlate with those of the extended chains of the original polymers both in the crystalline and amorphous states. Therefore, these structures were used for estimating the values of birefrin gence of the polymers, for which a new program called MBES was newly developed. It was found that the resulting values of birefringence based on the structural data of MM2 are more reliable than those calculated by the con ventional estimation method, especially for amorphous polymers.