A review on the enhancement of composite’s interface properties through biological treatment of natural fibre/lignocellulosic material

Natural fibre or lignocellulosic fibres have aroused the attention of scientists in the polymer industry, given their eco-friendly, low density, and biodegradability. Nevertheless, the major obstacle to wide commercial applications is the incompatibility between polar natural plant fibres with non-polar polymer matrix due to different chemical constitutions. Therefore, surface treatment of natural fibres before they are implemented to prepare fibre-reinforced composites is considered. Chemical and physical treatments are not preferred as it involves hazardous chemicals and high energy consumption. This review article provides an overview of various environmentally friendly approaches, such as introducing bacterial nanocellulose, pre-treatment with bacterial cellulase, fungal treatment, and enzymatic treatments aimed to treat natural fibres. The implications of working mechanisms on the characteristics of fibre itself and polymer composites with reinforcement are reviewed. The application of treated fibres reinforced composites and comparison of biological treatment with other treatments are discussed in this article. It is evidenced that fibre that undergoes biological modifications facilitates better fibre-matrix interfacial adhesion, has stronger mechanical bonding with the matrix, along with the reduction of water uptake of the composites.