Tensile and Thermal Properties of Crosslinked Chitosan/Empty Fruit Bunch Biofilms by Phthalic Anhydride

Abstract

Chitosan (CS) has high potential applications in packaging, agriculture and food. However, the cost associated with CS application is high. Therefore, the addition of agriculture waste such as empty fruit bunch (EFB) in CS has been studied in order to reduce the cost of CS. The CS/EFB biofilms are prepared through solvent casting method. This paper studies the effect of phthalic anhydride (PA) crosslinking agent on tensile, morphological and thermal properties of CS/EFB biofilms. The results indicated that the tensile strength and elongation at break of uncrosslinked CS/EFB biofilms decreases. However, the modulus of elasticity increases with the increasing EFB content. In addition, the glass transition temperature (T g) of CS/EFB biofilms increased with EFB content. The crosslinked CS/EFB biofilm with PA showed higher tensile properties (i.e., tensile strength, elongation at break and modulus of elasticity) in comparison with uncrosslinked biofilms. The T g of crosslinked CS/EFB biofilms, meanwhile, was higher than the uncrosslinked biofilms due to formation of amide linkages. The formation of amide bonds between CS and PA was analysed using the Fourier transform infrared (FTIR) spectroscopy. The better filler dispersion and filler-matrix adhesion were proven by scanning electron microscopy (SEM). It was further observed that the percentage gel fraction of both uncrosslinked and crosslinked CS/EFB biofilms increased with increasing of EFB content. On the other hand, the crosslinked CS/EFB biofilms exhibited higher gel fraction than uncrosslinked biofilms due to the formation of amide crosslinkages in crosslinked biofilms.