The Effect of CaCO3 Fillers on Processing and Mechanical Properties of UPVC Pipes

The effect of the particle size of natural calcium carbonate fillers on fusion behav ,LI! during processing, and subsequent mechanical properties of UPVC pipes has been investigated. Fine fillers were shown to aid fusion, while coarser particles hindered the process. Adequate tensile and impact strengths depended o n the achievement of optimum levels of fusion. This could further be modified by the presence of stearate coating on the fillers. The observed behaviour depends on the relative amounts of bound calcium stearate and unreacted stearic acid, which act as internal or external lubricants respectively.