Natural fibres moisture sensitivity

It has also been found that moisture absorbance of the natural fibre-polymer composite can be prevented if the fibre-matrix adhesion is optimized [15, 24]. Indeed, whereas composites based on standard PP and cellulosic fibres displayed high water content at the interphase, due to the presence of microcavities, the encapsulation of the fibres with MAPP decreased the water sensitivity of the composites in terms of both the water uptake and its diffusion coefficient [25], as shown in Fig. 19.9. 

Pott GT (2004) Natural fibres with low moisture sensitivity. Chapter 8 of book natural fibres, plastics and composites.In Frederick T (ed) Wallenberger, Kluwer Academic Publishers,... 

G.T. Pott, Natural fibres with low moisture sensitivity, in Natural Fibers, Plastics and Composites, ET. Wallenberger and N. Weston, (Eds.), pp. 105-122, Springer (2004). 

Several proteins have been extensively studied for their materials applications. Among them, soy protein is one of the most popular. Indeed, since the early 1930s it was used in phenol-formaldehyde blends for automotive applications. However, soy protein is sensitive to moisture and exhibits relatively low strength properties. Thus stabilization by plasticization, compatibilization or crosslinkage is required to maintain long-term performance of soy protein-based plastic materials. Also, several studies on soy protein-based blends with other natural polymers or their reinforcement by natural fibres have been performed. More recently studies on soy protein-nanoclay composites and polyfbutylene adipate-co-terephthalate) (PBAT) blends were also performed. 

The use of natural fibres does, however, have limitations. In particular, they are moisture sensitive, and their bonding with polymer matrices is relatively weak. In addition, there are concerns over natural fibre quality and consistency, as well as fogging and odour emissions, and processing temperature limits cannot go higher than 200°C. 

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