ON THE STRUCTURE OF GLASSY POLYMERS - 4. SMALL-ANGLE X-RAY SCATTERING FROM RIGID POLYVINYL CHLORIDE.

In the reported experiments, the small-angle x-ray scattering (SAXS) from quenched and annealed rigid PVC has been measured using a Bonse-Hart system. The scattering from annealed (6 days at75 degree C) and unannealed PVC was identical within experimental error, varying with scattering angle in a manner similar to the SAXS from other amorphous polymers. The intensity decreases rapidly with increasing scattering angle over the ranges from 20 sec to 20 min. The angular variation of intensity is well described by the scattering from heterogeneities of various sizes and concentrations superimposed on the scattering from thermal density fluctuations. It is pointed out that the results obtained are inconsistent with the presence of nodular features as representative of the bulk polymer. Rather, it is suggested that they are associated with surface effects. It is further suggested that previously indicated volume fractions of crystallinity in rigid PVC are incorrect, and that the model of a three-dimensional network of crystallites should be re-examined.