In this research, pure kenaf composite and kenaf/glass fiber hybrid composite was prepared by using hand lay-up process. The effect of weather on mechanical, morphology and thermal properties of pure kenaf composite and kenaf/glass fiber hybrid composites were studied. Tensile strength of kenaf I glass fiber hybrid composite was found to be at 130 MPa and tensile modulus was at 3030 MPa before weathering. Unfortunately, tensile modulus of both materials starts to decrease after the first weathering month through to the weathering periods with constant reduction of tensile modulus. However, the different of reduction between pure kenaf composite and glass fiber reinforced kenaf composite indicates that, glass fiber can be a good reinforcement candidate for high performance composites. From the flexural strength result obtained, it is clearly seen that natural fiber and their composites are not able to with stand environmental condition because they have poor wettability, incompatibility with some
polymeric matrices and high moisture absorption. Due to the high moisture absorption properties, there are formations of void in the composites which can reduce the mechanical properties of composite such as flexural strength or flexural modulus which is clearly supported by SEM results. For both pure kenaf composites and hyprid kenaflglass fiber composites before exposure to natural weathering show slow and steady initial weight loss until major weight loss at 390 °C The exposure to weathering the weight loss process started at 290 °C. This is due to photo-oxidation and thermooxidation which lead to surface oxidation, chain scission and breakdown of the tie molecules.
