Environmental degradation behavior of kenaf fiber mat composite

Nowadays "eco-design" is becoming a philosophy to guide next generation of materials and products as global environmental issue produced by fossil fuels and resource overusing. With an industrial increasing interest in sustainable, eco-efficient and green material's application, natural fiber in polymer composite is guided to develop rapidly. As well know that, natural fibers possess advantages over synthetic or manmade fibers due to its abundance, biodegradability, CO₂ neutrality, excellent price/performance ratio and comparable specific strength properties. However, outdoor applications of natural fiber composite are still constrained and raising concerns in terms of their durability, including UV resistance, moisture resistance and extreme temperature withstand and dimensional stability. Continuing with previous research on kenaf non-woven reinforced unsaturated polyester composites three months degradation performance, in order to get a good knowledge of its degradation process/cycle in complicated outdoor environments, longer degradation periods up to 6 months and 12 months in this paper were added for further investigation and comparison. Initially, three sets of kenaf fiber mat composite samples were located in extreme cold temperature (Harbin), mild sea climate Kyoto (Japan), subtropical marine monsoon climate Shanghai (China) and tropical monsoon climate Zaria (Nigeria) respectively from the same starting time until predetermined ageing periods, afterwards weight change and mechanical behavior in terms of tensile, flexural, impact and fracture toughness were measured instrumentally for ageing effect discussion and comparison. As expected, the aged specimens in those different positions all showed the dropped mechanical properties with increasing ageing periods. Furthermore, the trend of degradation in various mechanical parameters was established, which demonstrated weight loss made more serious effect on aged sample's mechanical properties' reduction than water absorption behavior. In a word, dropped mechanical properties of the degraded composites accompanied with weight change behavior were clarified, in which degradation phenomenon of embrittled the matrix polymer, deteriorated reinforced fiber and interfacial properties were detected.