Factors affecting the surface texture in extruded mica-polypropylene composites

A Taylor‐Hobson Talysurf instrument was used to quantify the surface roughness of phlogopite mica‐polypropylene extrudates. The rate of feeding and the speed of rotation of the screw were found to have a significant effect on the surface texture. Under the appropriate conditions of extrusion the roughness of 40 percent (by weight) mica‐filled polypropylene extrudates could be reduced by a factor of three. This effect was found to be independent of the extrusion rate.