Rheology of PVC compounds. II. Effects of lubricants on fusion

The effect of calcium stearate and paraffinic wax on the progression of fusion of PVC compounds was investigated by a rheological method based on the capillary entrance pressure loss. It was found that calcium stearate can increase or delay fusion. The way in which fusion is affected changes with temperature and the presence or absence of paraffinic wax. Increased calcium stearate levels in compounds with wax enhance the fusion process. Increased calcium stearate levels in compounds without wax decrease fusion at relatively low temperatures but accelerate fusion at higher temperatures. Paraffinic wax delays the resin particle breakdown and the fusion process. At the same level of calcium stearate, simple compounds without wax fuse faster than compounds with wax.