Effect of Adipic acid as crosslinking agent in nanocellulose reinforced chitosan biocomposites

Abstract

Rice straw is one of the residues from rice industry which found abundantly in Malaysia. Huge production of rice for the increased population has created a large amount of biomass waste in the environment and it is underutilized. Poor handling of agricultural waste and management of rice production had causes negative impacts to the environment. The present study investigated the effect of adipic acid on the properties of cellulose nanocrystal (CNC) reinforced chitosan biocomposite films. In this study, the CNC was isolated from rice straw and was used to reinforce chitosan biocomposites with the range of 0, 1, 2, 3, 4 and 5 wt%. Tensile testing, Fourier Transform Infrared (FTIR), Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD) and Differential Scanning Calorimetry (DSC) were carried out in this project. In the tensile test, both the chitosan biocomposites with and without adipic acid showed an optimum content of CNC 1 wt% in tensile strength. The result showed an increase in the tensile strength and Young's modulus but decrease in the elongation at break of chitosan biocomposites with 5 wt% of adipic acid. This outcome was due to the formation of amide linkage between the adipic acid and chitosan. SEM analysis shows the morphology surface of chitosan biocomposites with adipic acid was smoother than chitosan biocomposites without adipic acid. Besides, the high concentration of OH group observed in FTIR analysis signified the presence of crosslink chain between the chitosan and adipic acid. In XRD analysis, the crystallinity and the peak intensity of the chitosan biocomposites decreased after crosslinked with adipic acid. DSC analysis shows that chitosan biocomposites with adipic acid exhibited higher melting temperature (Tm) than chitosan biocomposites without adipic acid. In conclusion, the addition of adipic acid had improved the properties of chitosan biocomposites