Vital importance of moisture level in all stages of processing from calcium carbonate coating through polyethylene/calcium carbonate compounding to film generation

The scope of this work consists of studying the effects of powder premixing and drying conditions on the production of linear low density polyethylene (LLDPE) films containing calcium carbonate (CaCO3) particles surface treated with stearic acid, which are intended for use in breathable film applications. Coated calcium carbonates and powdered LLDPE were physically premixed and dried in different conditions and polymer compounds containing 45 and 55 wt.% coated calcium carbonate were generated using a twin screw extruder. The effects of coating conditions, filler amount, and drying conditions on the prepared compounds were studied by thermal and morphology analyses. In the final stage, cast films were produced and then evaluated in terms of physical appearance. It was revealed that a precise drying regime is required not only for the calcium carbonates before and after coating but also for the polyethylene/calcium carbonate mixtures before compounding and film generation to ensure that films that were free of macropores could be manufactured. (C) 2014 Elsevier B.V. All rights reserved