Effect of fiber size, cyclic moisture absorption and fungal decay on the durability of natural fiber composites

Abstract

This research investigated the effect of different lignocellulosic fiber sizes and additives on the durability of wood plastic composites (WPCs) after water absorption/desorption. WPCs were prepared by blending wood flour (20, 80, 120 mesh) with polypropylene (PP). Polypropylene grafted maleic anhydride (MA) and zinc borate (ZB) were added in the formulation to improve the properties of the WPCs. Our results show that the fiber size significantly affects moisture absorption and that the damage accumulates during the cyclic absorption tests and affects the mechanical properties. WPCs with finer wood particulates absorbed less moisture. Adding MA helped maintain the modulus and reduced the moisture absorption of the WPCs during cyclic moisture absorption tests. Because ZB may dissolve in water during the moisture absorption experiment, the addition of ZB did not retard a fungal attack. Although cyclic moisture absorption reduced the mechanical properties, it did not enhance the fungal attack.