The effect of lubricants on processing-part I. detection by PVC melt flow

For decades it has been recognized that one can detect molecular structural changes in the processing of PVC by using ASTM D 3364 [PVC Melt Flow Test]. In the course of this work, we also realized that this Melt Flow Test could detect small changes in the ingredients as well. Through a special design of experiment, the effect of three lubricants on extrusion of dry blends of PVC (with and without calcium stearate) has now been investigated. The effects of extrusion on extruded pellets have also been studied as part of this design. To detect the changes in lubricity, the techniques of ASTM D 3364 have been modified to include new higher pressures on the ram as well as other revisions. This report shows how the various lubricants at differing concentrations and types can alter the PVC Melt Flow Test results and imply differences in processing.