Thermal and flammability properties of wollastonite-filled thermoplastic composites: a review

Wollastonite has a huge potential to be utilized as a functional filler in the thermoplastic composites, providing an enhancement to the mechanical strength, as well as thermal stability and flame retardancy, thus replacing the other conventional fillers such as glass fibre and talc. Due to the reinforcing ability and good thermal stability of wollastonite, the wollastonite-filled polymer composites have attracted the attention of academicians and industrialists. Many studies are reported on the effect of wollastonite incorporation into the polymers, in the aspect of mechanical, thermal, and flammability properties, meanwhile exploring the potential of wollastonite usage in the desired applications. This review article will be focusing on the thermal and flammability properties of wollastonite-filled thermoplastic composites. The popular thermoplastics used as the matrix are polypropylene, polylactic acid, and poly(ethylene terephthalate). Studies on flammability properties of wollastonite-filled thermoplastic composites are relatively less compared to thermal properties. Generally, the properties of the composites are influenced by the wollastonite dispersion, loading, size and shape of wollastonite, and its interfacial adhesion with the polymer matrix. Most of the previous studies focused on thermoplastic filled natural micro-sized wollastonite composites. Thus, the effect of nano-sized synthetic wollastonite as a functional filler in polymers is worth investigating. Further research on hybrid wollastonite/nanofillers is also interesting to develop high-performance materials to meet the requirements of society and industries.