Thermo-Mechanical Processing of Chitosan Using Cyclic Carbonates as Green Plasticizers

Chitosan is processed employing cyclic carbonates (ethylene carbonate (EC), propylene carbonate (PC), their mixture, and carbonated diglycidyl ether of bisphenol A (CDGEBA)) and sorbitol (S) (control) as plasticizers by melt mixing and compression molding. It is observed that 5% of cyclic carbonates (by weight of chitosan) is optimum for plasticizing chitosan to achieve desirable mechanical properties compared to 30% S. The tensile and tear strength of the cyclic carbonate-based films are on par with the S-based films. Morphological observations showed the presence of microfibrils in all samples. Structural and thermal analysis revealed the presence of two different phases in the plasticized chitosan namely amorphous and crystalline. Interestingly, all the plasticized films are found to have good antimicrobial activity. PC is a better plasticizer than S as the resulting films do not show a significant drop in the mechanical properties over three molding cycles.