The effects of filler size on the properties of thermoplastic polyolefin blends

The effects of filler size on the properties of a thermoplastic polyolefin (TPO) blend were examined by using wollastonite and talc with particle size s ranging from 1.2 to 40 mu m. While addition of filler produced significan t changes in the mechanical properties of the blend, filler size affected o nly impact strength. However, filler size, filler coating, and injection sp eed had a major effect on the surface properties of the blend. Faster injec tion produced denser "shear zone layers" which exhibited better scratch res istance and poorer paint adhesion than those obtained with slower injection . Scratch resistance and paint adhesion also decreased with Increasing fill er particle size. Filler coatings altered the scratch and adhesion properti es of the polypropylene (PP) blends.