Properties of Calcium Carbonate-Filled Polyethylene Bottles Produced From Extrusion Blow Molding Process

This research concerns in property testing of CaCO₃-filled high density polyethylene (HDPE) for blow molding applications. Both uncoated and stearic acid (SA) coated CaCO₃ grades were used at 20%wt filler loading whereas maleic anhydride grafted high density polyethylene (HDPE-g-MA) was used as a compatibilizer (at 0.5-4.0% contents). All compounds were prepared using a twin-screw extruder and an extrusion blow molding machine was used for bottle production. It was found that an addition of CaCP₃ increased the compound viscosity, however, the viscosity did not change when SA or HDPE-g-MA was present. From the below molding process, all the compounds had similar volumetric output rate. The bottle weight of the unfilled HDPE was less than that CaCO₃-filled HDPE, but the bottle thickness gave opposite results. An incorporation of CaCO₃ fillers in HDPE decreased tensile yield strength, elongation at break and impact strength, but these properties could be improved by an addition of SA or HDPE-g-MA. Modulus of the CaCO₃-filled HDPE was greater than that of the unfilled one, but decreased when having HDPE-g-MA. It could be possible to use 20%wt CaCO₃-filled HDPE compounds for the extrusion blow molding applications since the deleterious effect of CaCO₃ incorporation could be reduced by an addition of SA or HDPE-g-MA.

Keywords: Calcium carbonate, Polyethylene, Blow molding process, Mechanical properties

Corresponding author: E-mail: kjsupara@kmitl.ac.th