Thermoformability Study Of CaCO₃ Filled Polypropylene

This work deals with the thermoformability of calcium carbonate CaCO3 filled polypropylene PP sheet intended for packaging applications. The effect of calcium carbonate was investigated. Formulations of virgin polypropylene (PP) and 10, 20, 30 and 40 wt % of calcium carbonate were prepared and melt compounded in a single screw extruder, then compression molded to get an about 1 mm thick sheets. Vacuum forming on a constructed laboratory scale machine seems to be an adequate way to select the appropriate thermoforming conditions (temperatures and draw ratios) for CaCO3 filled polypropylene. Rheological, thermal as well as mechanical tests were performed in terms of filler effect in order to optimize properties while improving processability. The MFI slightly increased, the HDT increased, the tensile properties decreased but the impact strength increased. 30% by weight of CaCO3 filler can be incorporated into polypropylene with relatively minor effects on vacuum forming properties. The presence of CaCO3 leads to 50% reduction the thermoforming cycle time.