Preparation, characterization, and properties of polyethylene composites highly filled with calcium carbonate through co‐rotating conical twin‐screw extrusion

A series of highly filled polyethylene (PE) composites in which the calcium carbonate content was as high as 50–75 wt% was prepared by co-rotating conical twin-screw extrusion (Co-RCE). The effects of Co-RCE processing and CaCO3 content on the morphology, structure, and properties were investigated in detail. The results indicated that the Co-RCE processing improved the filler dispersion and thereby enhanced the melt processability of the blends. Observation by polarized light microscopy and analysis by differential scanning calorimetry and wide-angle X-ray diffraction showed that the crystallinity of PE decreased with the increase of CaCO3 content. In comparison with neat PE, an increase of up to 20oC in onset weight loss temperature was observed in the CaCO3-filled PE composites, as confirmed by thermogravimetric analysis. Tensile tests indicated that the elongation at break of the highly CaCO3-filled PE composites was much higher than that of the neat PE. Meanwhile, the highly filled composites still exhibited superior tensile strength. J. VINYL ADDIT. TECHNOL., 20:108–115, 2014. © 2014 Society of Plastics Engineers