Fusion of particulate structure in polyvinyl chloride during powder extrusion

It has been recognized recently that suspension polyvinyl chloride granules consist of particles ca 1μ in diam which are linked together to form a three‐dimensional, sponge‐like lattice. This paper deals with the fusion process of this particulate structure of PVC resin during powder extrusion. Extrudates prepared under various extrusion conditions are investigated through the electron microscope using a methyl methacrylate (MMA) embedding method followed by ultrathin sectioning. The MMA embedding method has been proven to be an effective means of revealing the detailed structure of molded PVC. Results showed that the 1μ‐particles were subjected to breakdown due to heat and shear into fibrils 100‐300 Å in thickness, which were the final structure attainable by extrusion. Discussion was focused on the fibrillar structure especially in relation to the elasticity in plasticized PVC.