The effect of alkalization and bleaching treatment of Sorghum fibre on the crystallinity index of PP composite

Natural fibres are increasingly being employed as the reinforcing material for polypropylene (PP). However, the fibre surface needs to be modified with particular treatment to improve the interfacial adhesion and thus mechanical properties of the composite. The aim of this work was to study the effect of alkalization and bleaching treatment to the structure of sorghum fibre and how it affects the crystallinity of polypropylene (PP)-sorghum composite. For the alkalization treatment, the fibre was soaked in NaOH solution 10% v/v while for the bleaching treatment NaClO2 solution 1.7% v/v was used. The FTIR and SEM analysis of the sorghum fibres indicated that the alkalization and bleaching process eroded some part of amorphous structure in the fibre. It was found that using the treated fibre as the reinforcing agent in PP matrix could increase the crystallinity of the resulting composite compared to the crystallinity of pure PP.