Mechanical and morphological behavior of polyolefin blends in the presence of CaCO3

The aim of the present work is to study the properties of blends of Polypropylene (PP) with virgin and recycled high density polyethylene (r-HDPE) (80/20), functionalized and non-functionalized EPR (5 wt%), and calcium carbonate (30%) as it is untreated or treated with a 1% by weight of coupling titanate agent. The mechanical behavior of PP/HDPE/EPR blends showed that functionalization was not effective. When blends of PP/HDPE/EPR with treated or untreated filler were compared to the equivalent ones, but with recycled HDPE and untreated filler, a slight increase was observed in elongation at break and a decrease in Young's modulus and impact strength. This behavior may suggest that recycled HDPE and EPR together act as a plastifier in these blends. It was also found that the use of treated calcium carbonate did not contribute to obtain better mechanical properties. From these results it can be concluded that it is possible to recycle HDPE in blends with PP and non-functionalized EPR (nf-EPR), using untreated calcium carbonate as a filler, and that this offers economic advantages and produces a material with mechanical properties comparable to those of the compounds of PP with filler. (C) 1999 Elsevier Science Ltd. All rights reserved.