Influence of pre-treatments on the mechanical properties of palmyra palm leaf stalk fiber–polyester composites

Palmyra palm leaf stalk fibers were subjected to various chemical pre-treatments like Mercerization, benzoylation, and permanganate treatment with the aim of improving the adhesion with the matrix. Composites were prepared by reinforcing untreated and pre-treated fibers in unsaturated polyester matrix and mechanical performances are studied. The Mercerized and benzoyl-treated fiber composites had an improvement of around 60% in tensile strength while the tensile modulus increased by 37% and 60%, respectively. In the case of permanganate-treated fiber composites, the flexural strength increased by 70% and flexural modulus increased by 110% in comparison to the untreated composites. The impact strength for the Mercerized and permanganate-treated fiber composite improved by 55% and 42% in comparison to the untreated fiber composites, respectively. Chemical pre-treatment of fibers reduced water absorption of the composites. The benzoyl chloride treated fibers absorbed less water in comparison to the untreated fiber composites. Thermogravimetric analysis showed that the reinforcing-treated fiber has enhanced the thermal stability of the composites. Scanning electron microscope fractographs of the composites revealed the presence of good adhesion between the fibers and matrix compared to the untreated fiber composites. The composites exhibited comparable properties with other composites based on natural fibers.