Physicomechanical behavior of composites of polypropylene, and mineral fillers with different process cycles

Abstract

In this work, a development of composites of polypropylene [PP] with mineral fillers [M] of talc and calcium carbonate [CaCO3] by co-extrusion and injection techniques were carried out. In the preparation of the mixtures, was used the rheometric analysis to define the optimum temperature of the extrusion process, and a weight ratio of 80:20 PP: fillers was maintained, while for the injection molding process six generations of PP and its compounds were obtained to study the rheological, thermal, morphological and mechanical properties of the new series of PPnM composites formed from a recycled matrix and the PPMn series reprocessed compounds for up to six cycles. The results allowed correlating the changes due to the thermal history and the influence of adding the mineral fillers. The mechanical characterization in the reprocessed matrix indicated a 6.0% decrease in tensile strength and an increase in flexural strength of 9.9%. Likewise, the compounds showed an increase in tensile strength of 11.7%, while flexural strength reached 35.8%. From the thermogravimetric analysis, the degradation temperature in the matrix gradually decreased from 406.5 °C to 364.3 °C, for the sixth generation with respect to the virgin material by the injection process; meanwhile, for the compounds was maintained around 410 °C indicating an optimal interaction, these results could be contrasted with the colorimetric analysis. Finally, re-injection led to a significant decrease in the size of the talc and CaCO3 particles; the sizes were estimated from microstructural analysis from Scanning Electron Microscope.