| Abstract: | Unidirectional isora fibre reinforced polyester composites were prepared by compression moulding. Isora is a natural bast fibre separated from the Helicteres isora plant by a retting process. The effect of alkali treatment on the thermal properties of the fibre was studied using TGA, DTA and DSC in oxygen and nitrogen atmosphere. Mechanical properties like tensile strength, Young's modulus, flexural strength, flexural modulus and impact strength of the composites containing untreated and alkali-treated fibres have been studied as a function of fibre loading. The optimum loading for tensile properties of the composite containing untreated fibre was found to be 45% by volume and on alkalization of the fibre, the optimum loading increased to 66%. For flexural properties the loading was optimized at about 56% and 66%, for the composites containing untreated and alkali treated fibres, respectively. From DMA studies it was observed that the alkali-treated fibre composites have higher E′ and E″ values compared to untreated fibre composites. From swelling studies in styrene it was observed that the mole percent uptake of the solvent by the treated fibre composites is less than by the untreated fibre composites. From these results it can be concluded that in composites containing alkalized fibres there is enhanced interfacial adhesion between the fibre and the matrix leading to better properties, compared to untreated fibre composites. |
