Compatibility, Microstructures and Performance of Polylactic Acid, Epoxidized Soybean Oil and Cellulose Fiber Eco‐Composites

ABSTRACT

Nowadays, natural fibers reinforced bio‐composites have achieved remarkable development, but their shortcomings in low toughness, high hydrophilicity and poor heat resistance cannot be ignored. Herein, epoxidized soybean oil (ESO) and wood‐based cellulose fiber (CF) are used as the plasticizer and reinforcing filler to modify polylactic acid (PLA). In order to boost interfacial adhesion and compatibility of the composites, the silane coupling agent KH 580 (3‐mercaptopropyl triethoxysilane) was used to treat CF. The epoxy‐carboxyl and epoxy‐thiol dual reactions during the melt‐blending are utilized to promote the compatibilization of ternary components. The tensile strength of 1 wt% K0‐CF composite is 47.25 MPa, which is 1.22 times greater than that of unmodified CF composite; meanwhile, the notched impact strength of 1 wt% K0‐CF composite is 6.23 ± 0.38 KJ/m ² , which is 1.2 times higher than that of pure PLA. The addition of K0‐CF enhances the hydrophobicity, interfacial adhesion, melt viscosity and elasticity of the composites. The initial decomposition temperatures and residues of the composites are significantly increased due to excellent thermal stability of CF. Both fibers promote the crystallization of PLA, especially for unmodified CF. Due to excellent mechanical, rheological and thermal properties of PLA/ESO/K0‐CF composites, they show potential applications in packaging fields.