2. Classification of natural fibers

Natural fibres can be subdivided into three main groups according to their origin (figure 1 ):

• plant fibers, which can come from bast plants (flax, hemp, etc.), leaves (sisal, etc.), fruits (coir, etc.), herbs (arundo donax, etc.), straw (wheat, etc.), wood (softwood, hardwood) and pseudo-trunks (banana, etc.);

• animal fibres, which come from hair, such as animal fleece, and secretions, such as silk;

• mineral fibers such as asbestos. This type of fiber must be handled with great care, as it is highly toxic to the human respiratory system. This family of fibers, mentioned for the record, will not be presented in this article, as previously indicated....