Hydrophobizing Paper Surfaces Using Soybean Oil And Starch

Abstract

A significant global concern nowadays is plastic pollution, which is highly damaging to ecosystems and public health. Consequently, development of alternative materials derived from biodegradable natural polymers is important in curbing this threat. In this study, starch was modified to be water resistant by treating starch-DMSO solutions with soybean oil at high temperature in the presence of sodium carbonate. The modified starch was evaluated by FTIR analysis and contact angle value measurement of paper coated with it. FTIR analysis of modified starch samples confirmed the substitution of hydroxyl groups with fatty acid ester and provided an estimate of the degree of substitution (Machell & Richards). The hydrophobicity of the coated paper was quite high, and was a combination of two factors: changes in starch particle surface features by replacement of hydroxyl groups with fatty acid chains and the high-roughness surface of coated paper. The contact angle measurement of starch-coated paper surfaces revealed values as high as 121o, demonstrating the high hydrophobicity of the modified starch coating and its potential as a water-resistant treatment for non-plastic materials, though some water absorption was still present due to shortcomings of the coating and modification process. Overall, with more research and refinement, this process has the potential to allow the widespread adoption of similar hydrophobic modified biomaterials to replace plastic in daily life.