Mechanical parameters of chitosan film with glycerol and propylene carbonate

Abstract

Chitosan films were prepared by incorporating glycerol (GLY) and propylene carbonate (PC) to enhance their mechanical performance for applications in which material conformability is prioritized over mechanical strength. The addition of GLY significantly increased the flexibility of films, with the elongation at break reaching values approximately four times higher than those of unplasticized chitosan. Although PC is not an effective plasticizer as GLY when used alone, its combination with GLY produced a synergistic effect that further enhanced film flexibility, achieving elongation values up to six times greater than the unmodified chitosan. This improvement was accompanied by a marked decrease in tensile strength and elastic modulus, not only due to the individual plasticizing effects of GLY and PC, but also as a result of their combined interaction, which disrupts interchain hydrogen bonding and increases polymer chain mobility. The optimal mechanical profile was observed at a composition of 30% GLY and 15% PC, yielding an elongation at break about 66%, an elastic modulus of 24 MPa, and a tensile strength of 17 MPa. In addition, thermal analysis revealed improved thermal stability, attributed to structural changes induced by the incorporation of both plasticizers. Overall, the results highlight the potential of using a GLY–PC blend to fine-tune the mechanical and thermal properties of chitosan films, making them promising candidates for sustainable and conformable environmentally friendly materials.