New type of thermoplastic bio composite: nature of the interface on the ultimate properties and water absorption

A new type of thermoplastic bio composite with coir fibre derived from coconut was fabricated by means of plasma modification of the polymer surface. Plasma modification is an effective and eco friendly method to create hydrophilic polymer surfaces. Plasma modified polyethylene (PE) was used as the matrix for coir fibre reinforced composites. The use of compatibilizers, and chemical modification of fibre or polymer is a usual practice to improve the interfacial adhesion and to make the fibre and polymer matrix compatible. Here, plasma modification of PE was introduced as a new method to improve the compatibility. The present study involves the preparation and characterisation of plasma modified PE (PPE) and coir fibre composites. Different preparation methods were followed and the composites prepared by a hot press method proved to be better. The mechanical properties of the composites were compared with unmodified PE/coir fibre composites. The newly prepared thermoplastic composites based on PPE and modified coir fibre showed lower water absorption due to better fiber/matrix interaction. We could observe different kinds of interfaces in the composites. In the plasma modified one, a good wetting of fibre by the matrix eliminated the possible microvoids. Finally, it is important to add that plasma modification of the polymer was found to be an effective technique to improve the compatibility between polyethylene and natural fibre.