Cross-Linked Waxy Maize Starch-Based Green Composites

In this research, green composites were fabricated by blending waxy maize starch (WMS) with micro/nanofibrillated cellulose (MFC). Further, an environmentally friendly, sustainable, and water-soluble cross-linker, 1,2,3,4-butane tetracarboxylic acid (BTCA), was used to cross-link WMS to fabricate cross-linked starch-based composites. The method described here provides a benign and convenient way to produce cross-linked starch-based composite films 300 pm in thickness), comparable to commercially available plastic sheets. The process can be easily scaled up for commercial production. Industrially pregelatinized WMS was used to obtain smooth, transparent, and defect-free films. Cross-linking helped in reducing the moisture absorption as well as made the films and composites insoluble in water. MFC (15% MFC)-cross-linked WMS composite films exhibited excellent tensile properties with a Young's modulus of over 2.3 GPa, fracture strain of 3.1%, and fracture stress of 39 MPa, as a result of MFC incorporation. The toughness of these composites was also significantly higher, even without the use of plasticizers such as sorbitol. These materials can be good candidates for replacing petroleum-based resins such as epoxies and their composites.