Vibrational analysis of chain folding in polyethylene crystals

Abstract

The vibration frequencies of a polyethylene crystal lattice have been computed for various structures in which a fully deuterated chain is mixed with a normal chain. Intermolecular potential functions previously developed by the authors were used in the calculation. It is shown that such structures make it possible to distinguish experimentally between chain folding in the (110) plane and folding parallel to the (100) plane. Calculations have also been done for a regular polymer of (CH 2 CD 2 ). Such a structure would permit the determination of the parity of the number of methylene groups in the fold.