Processing, morphology, and properties of PVC

This article describes the effect of the extrusion conditions on PVC processing, morphology, and physical properties. In agreement with several previous reports, the PVC particulate hierarchy is successively broken down during processing. In particular, the 100—150-μm PVC grains are broken down to 10-μm agglomerates and these in turn reduce to 1-μm primary particles which appear to be the major flow unit in most processing operations. These results support prior suggestions that the primary particles can become the major flow unit. In addition, our work shows that the method and rate by which the primary particles become the major flow unit depends on the extrusion condition. The ultimate physical properties are dependent on the degree of homogenization achieved, whereas the small strain (yield) properties are independent for the conditions used.