Effect of chemical treatment on mechanical and thermal properties of kenaf fiber mat reinforced unsaturated polyester biocomposites

Kenaf fiber mat (KFM) reinforced unsaturated polyester (UPE) biocomposites have been prepared using hand lay-up and compression moulding technique. To improve fiber matrix adhesion, the KFM was chemically treated with 6% alkaline (NaOH) solution at different soaking time range from 0 to 6 hours. Fourier transform infrared red (FTIR) and thermogravimetric analysis (TGA) were used to investigate the changes of fibers chemical constituents and thermal behavior after alkaline treatment. Mechanical properties such as tensile and flexural strength, tensile and flexural modulus and elongation at break of untreated and alkaline treated KFM-UPE biocomposites were also studied and compared. The incorporation of the alkalized KFM resulted in composites better tensile and flexural properties and 3 hours treatment showed best results. Thermal stability of the KFM-UPE biocomposites were significantly enhanced after alkaline treatment compared to those of untreated KFM-UPE biocomposites. FESEM morphological studies showed that the alkali treatment provided adhesion of the fiber-matrix interaction better. Thus, the chemical treatment on KFM improved fiber-matrix adhesion, which also contributed to the improvement of mechanical properties and thermal stability compared to those of untreated KFM-UPE biocomposites.