REACTIONS AT FOLD SURFACE OF POLYVINYLIDENE CHLORIDE CRYSTALS

The rate of dehydrohalogenation of polyvinylidene chloride (PVDC) with pyridine was followed by conductometric titration. Kinetic and infrared data of the reaction products indicated that dehydrohalogenation of the polymer proceeded in a step-wise manner. Kinetic data were found to support the calculated percentage of chlorine evolved of a model system, calculations being made from the thicknesses of lamellae observed on electronmicrographs. The thicknesses obtained were in good agreement with those from X-ray small angle data, which also indicated that the crystal fold surface was the site of reaction. D.T.A. results could be explained in terms of block copolymer system, which the reaction site suggested. D.S.C. data indicated changes in crystalline order which were explicable in terms of reactions at the fold. The overall picture of a step-wise dehydrohalogenation at the fold surface may be generated from consideration of the energetic and steric requirements for attack at a proposed fold model. Of the several models available to describe the amorphous" portion of single crystals it is felt that the regular fold structure in a fold surface is most compatible with the data. © 1969."