Surface hydrophobic modification of starch with bio-based epoxy resins to fabricate high-performance polylactide composite materials

The surface hydrophobic modification of starch was firstly made by use of two bio-based epoxy resins to fabricate the fully bio-based polylactide (PLA)/starch composites with superior mechanical and thermal properties. As demonstrated by FT-IR and 1H NMR, the surface of starch was successfully modified with the epoxidized itaconic acid (EIA) or epoxidized cardanol (Epicard) to produce hydrophobicity with the contact angle increasing from 44° to ∼100°. After modification, the interfacial adhesion between starch and PLA was obviously improved, which can be clearly observed by SEM. As a result, an obvious increase of tensile strength from about 35 MPa to over 50 MPa was obtained. Moreover, with the strong interaction formed at the interface between modified starch and PLA, the crystallization ability of PLA was also enhanced as confirmed by DSC and DMA. This study suggested us a simple but effective surface modification technique by utilizing the bio-based epoxidized modifiers to improve interfacial adhesion in fabricating fully bio-based PLA/starch composites with superior properties.