ABSTRACT

In polymer technology, there are essentially two major classes of fillers, either extracted or fabricated. Minerals such as talc and clays (Al2O3, 2SiO2, 2H2O) are extracted, grinded, and possibly treated and therefore belong to the first class. Calcite (CaCO3) belongs to both classes, as it can be either extracted and grinded or obtained through a chemical process that involves precipitation. Carbon blacks result from the incomplete combustion of hydrocarbon feedstock, and are consequently fabricated fillers, as well as synthetic silica that are obtained through more or less complex chemical operations. Short fibers made either of glass, or of carbon, are fabricated products, and we arbitrarily include cellulose fibers also in the second class, because quite complex treatments are required before they can be used as a polymer reinforcing material. Moreover, many types of natural fibre have been considered for use in polymers as reinforcing materials including flax, hemp, jute, straw, wood flour, rice husks, sisal, raffia, green coconut, banana, and pineapple leaf fibre to name a few, but technical problems such as moisture absorption and low impact strength have sometimes restricted their development. Wood flour nowadays used to prepare so-called woodpolymer composites (WPC), which represents a growing market over the last decades,* can also be considered as a fabricated filler with respect to its preparation mode.