Preparation And Properties Of Glutamate / Chitosan Composite Membrane For Crosslinking Wheat

With the development of oil industry, synthetic polymer was widely used in almost every area in our daily life nowadays. However, it also caused some serious problems, such as overconsumption of oil and environment pollution all over the world, which has resulted in the fact that biodegradable package films becomes a hot research area.Gliadin/chitosan composite film have not only the excellent cohesive and elastic properties, ductility, and easily film forming property of gliadin, but also the antimicrobial and good mechanical properties of chitosan. But the relatively low mechanical strength still limits the application of the composite film without crosslinking.Glutaraldehyde and L-cysteine were two kinds of crosslinker with different mechanisms. They were used separately to crosslink gliadin/chitosan composite film through solution-casting method in this paper to study the influence of the species and addition of the crosslinker on the morphology, mechanical properties, water absorption and solubility of the composite film. Impact of the environment relative humidity was also tested. The influence of thermal treatment that was also researched.According to the results, the two kinds of crosslinker mentioned above can both significantly enhance the mechanical properties of the composite films, which are much better than gliadin-based films modified by several ways or gliadin/chitosan composite film without crosslinking. Glutaraldehyde initiates strong interface interaction between gliadin and chitosan, degree of phase separation was lowered as a result. Therefore, water absorption and solubility of the composite film decreased with the increase of glutaraldehyde. L-cysteine has no effect on phase separation of the composite film out of a totally different crosslinking mechanism. Solubility of the film slightly increased with more L-cysteine added in while water absorption kept constant broadly despite of the addition of L-cysteine crosslinker.Properties of both the two kinds of crosslinked composite films have a dependence on environment relative humidity. When the RH goes up, mechanical properties of the crosslinked composite film deteriorated obviously and water absorption increase greatly. In comparison, glutaraldehyde crosslinked composite film was superior to L-cysteine crosslinked composite film, with less sensibility to environment relative humidity. Thermal treatment can enhance the crosslinked network, so that elongation at break, swelling degree, solubility were reduced, while moisture absorption stayed still. Tensile strenth of glutaraldehyde crosslinked composite film was improved and that of L-cysteine was reduced slightly as contrast.