Physico-chemical Aspects of Fillers in Polypropylene

Fillers and reinforcing materials for thermoplastics are generally solid additives which differ from the polymer matrix by their composition and structure. An exact differentiation, however, between fillers and reinforcing materials is difficult. In general, additives improving the tensile strength and tensile strength at break of filled polymers should be designated as reinforcing materials, whereas additives decreasing these properties are generally termed as fillers or extenders. In thermoplastics, both fillers (excluding air) and reinforcing additives have only four things in common: they increase the volume, enhance stiffness, decrease the elongation and thermal expansion, and improve the dimensional stability of the finished parts.--AA