Non-Toxic Crosslinking of Starch Using Polycarboxylic Acids: Kinetic Study and Quantitative Correlation of Mechanical Properties and Crosslinking Degrees

Abstract

For the first time, kinetics of citric acid crosslinking of starch was studied, and mechanical properties of starch films were quantitatively correlated with crosslinked degrees and structures of polycarboxylic acids. To substitute toxic crosslinkers to improve the properties of bio-derived polymers, non-toxic polycarboxylic acids were widely used to improve the performance properties of starch-derived industrial products, and were proved effective. However, the mechanism of the reaction and relationship between crosslinking extents and performance properties of starch products had not been clarified. In this study, crosslinking of starch by polycarboxylic acids was verified, and logarithmic relationship between crosslinking degree and strength was elucidated. The polycarboxylic acids with more carboxyl groups could more effectively improve the tensile properties of starch films. In general, crosslinking using polycarboxylic acids might improve the mechanical properties of starch products in a controlled manner and thus could facilitate their industrialization.