Morphological progression and elasticity development in the single-screw extrusion of rigid PVC

The morphological progression of rigid PVC compounds during single-screw extrusion is examined in relation to the melting mechanism and elasticity development. It is shown that no grain destruction occurs in the solid bed. 100-μm domains persist in the solid bed after extensive intergrain fusion has occurred. The melt pool is composed of clusters of primary particles in the early screw flights, but shows no evidence of particulate structure of this size in later flights. A capillary rheometer entrance pressure test is used to demonstrate the development of elasticity in both the solid bed and melt pool. Development of elastic response progresses at a higher rate in the solid bed of mass resin-based compounds. Elasticity of the melt pool is high at all stages of extrusion, but also shows a progression.