Synthesis and characterization of starch/fiber-based bioplastic composites modified by citric acid-epoxidized palm oil oligomer with reactive blending

In the present work, starch and empty fruit bunch-based bioplastic composites were modified with epoxidized palm oil (EPO) or citric acid-epoxidized palm oil (CEPO) oligomer using melt blending in order to improve the mechanical and water resistance properties. As evidenced by the FTIR, CEPO generated strong interactions with starch/fibers via citric acid-inspired esterification reaction. The X-ray diffraction patterns of the composites were apparently changed by CEPO because of the crosslinking effect. The SEM micrographs showed that EPO was immiscible with starch and hence migrated to the composite's surface. The compatibility between starch and CEPO was obviously improved. EPO contributed to a noticeable decrease in melting temperature (T-m) of the composites, while CEPO improved T-m due to its crosslinking effect. As a result, the blending of CEPO in the composites led to the higher evolution in the tensile strength and young's modulus than EPO. The tensile strength and young's modulus of the control sample increased from 3.67 MPa to 6.90 MPa and from 27.19 MPa to 88.74 MPa, respectively, after the addition of 0.75 wt% CEPO. Higher concentrations of EPO or CEPO toughened the composites. The water sensitivity and permeability of the composites were also slightly reduced upon the addition of both oils. This study proposed a simple and effective modification technique by utilizing the CEPO oligomer to fabricate the bioplastic composites with superior properties.

Automated summary

In this study, starch and empty fruit bunch-based bioplastic composites were modified with epoxidized palm oil (EPO) or citric acid-epoxidized palm oil (CEPO) oligomer using melt blending to improve mechanical properties and water resistance. The incorporation of CEPO led to stronger interactions with starch/fibers and changes in X-ray diffraction patterns, resulting in improved tensile strength and young's modulus. EPO decreased the melting temperature of the composites, while CEPO increased it due to crosslinking effects. The addition of both oils also slightly reduced water sensitivity and permeability of the composites.