Rice stubble reinforced polymeric composites: Improvement in hygrothermal durability through fibre pre-treatment

Abstract

Currently, there is a lack of comprehensive scientific knowledge on the response of hygrothermal ageing of rice stubble-based composites, which limits their potential applications. In this work, the effect of alkali and water pre-treatment on the hygrothermal ageing, mechanical strength, contact angle, and morphology of the rice stubble fibre-reinforced polymer composites is presented. The rice stubble-reinforced polymer composites are fabricated using two different weight fractions (50% and 60%) of stubble inside the polymer matrix resin. Accelerated environmental ageing is performed inside the temperature-controlled water bath and moisture-controlled humidity chambers for 7 and 14 days. The results of environmentally aged specimens are compared with untreated virgin specimens. The tensile strength of stubble polymer composites is improved by ∼177% (65%), using water (alkali) pre-treatment. There is a notable improvement in the flexural modulus as well. The mass gain analysis is conducted in temperature-controlled submerged environments. The water pre-treatment reduced the mass gain by ∼20% and the contact angle by ∼18%, in comparison to the untreated composites. Although both pre-treatments resulted in a significant improvement in the hygro-mechanical properties and wettability characteristics of the composites, the water pre-treatment appears to be more promising in comparison to the alkali-treatment. The findings have significant implications for spurring the development of rice straw-based polymer composites through proposed pre-treatments. The usage of stubble waste composites for low to medium load-bearing applications, such as furniture, partition boards, and packaging materials can help curb the stubble burning practice and save the environment.