Extraction and Characterization of Calotropis gigantea Bast Fibers as Novel Reinforcement for Composites Materials

The aim of this study is to scrutinize the use of Calotropis gigantea bast fibers as potential reinforcement in polymer composites. The bast fibers were extracted from the Calotropis gigantea plant bark and some of them were treated with alkali (5 wt.%) solution. The chemical composition, physico-chemical structural properties of the untreated and the alkali treated Calotropis bast fibers were studied. The results of chemical composition analysis indicated that alkali treatment removed most of the non-cellulose materials as confirmed by the FTIR analysis. The X-ray diffraction results exhibited that the crystallinity index of the alkali treated fibers increased in comparison with the untreated fibers, which agrees with the results obtained in the mechanical tests. The tensile strength and modulus of the alkali treated fibers were found to be higher whereas the elongation at break was lower than the untreated fibers. Thermal stability of alkali treated fibers was lower than that of the untreated fiber. Scanning electron micrographs showed roughening of the surface of the fiber due to the removal of the surface impurities and non-cellulosic components on alkali treatment. It can be concluded that alkali treatment is an effective method to improve the surface and mechanical properties of Calotropis bast fibers to be used in composite materials.