Talcs

Abstract

Talc is a naturally occurring magnesium silicate mineral, widely used as a polymer filler. Its main differentiating features in this context are its softness (it is the softest mineral known) and lamellarity (platiness). Useful deposits are widespread and processed by conventional mining operations to produce filler grade material. The platiness depends on the source and manufacturing methods. The main use for talc is in thermoplastics, such as polypropylene, where it gives a useful balance of strength and stiffness, together with increased heat distortion temperature and creep resistance. The platy nature also provides better gas barrier properties than blocky fillers like calcium carbonate. Significant issues with talcs in composites are the limited response to coupling agents such as organo-silanes and accelerated heat aging due to impurities which varies with the origin of the deposit.