Lauric acid-grafted barley (Hordeum vulagare L.) husk for application in biocomposite films: optimization method in synthesis and characterization

摘要

Lauric acid-grafted barley (Hordeum vulgare L.) husk (BH) samples were prepared in the presence of redox initiators. The effect of reaction time, reaction temperature, dimethyl sulphoxide content, and concentration of lauric acid on the percentage of graft yield of BH was studied through one-variable-at-a-time approach. A second-order mathematical response model was developed using response surface methodology coupled with central composite design to examine the individual and combined effect of grafting reaction parameters on the percentage of graft yield of BH. The regression model showed a good fit with the experimental data with high correlation coefficient (R-20.97). Grafted BH samples were characterized using Fourier transform infrared spectroscopy, X-ray diffractometry, scanning electron microscopy, and thermal analysis techniques. Crystallinity of BH decreased from 55.5 to 30.22% after grafting with lauric acid due to destruction of crystalline structure of BH during grafting reaction. Grafted BH was more thermally stable as compared to BH. Water contact angle of grafted BH was higher than that of BH, indicating the improved hydrophobicity of BH after grafting. Swelling studies of grafted BH samples in different solvents such as water, ethanol, and dimethyl formaldehyde were performed and compared with BH.