Improved compatibility of PLA/Starch blends with Binary functional monomers through UV-induced reactive extrusion

In this work, we chose starch as a biomass nucleating agent for PLA to enhance the crystalline properties without affecting the biodegradability of the composite. Under the synergistic effect of glycidyl methacrylate (GMA) and trimethylpropane triacrylate (TMPTA), biodegradable PLA/Starrch composites were prepared by a unique UV-induced reactive extrusion technique. GMA was grafted onto PLA with the help of TMPTA and the modified PLA enhanced compatibility with starch via epoxidation reaction during extrusion. The rheological properties, mechanical properties, and crystallization behavior of PLA/Starch composites were researched. The rheological and FITR results demonstrated that the introduction of GMA/TMPTA in PLA/Starch blends not only promoted the reactive compatibilization of PLA with starch but also produced a certain degree of chain branching effect. Meanwhile, starch provides heterogeneous nucleation sites for PLA crystallization, which improved the crystallization performance of PLA. In addition, the mechanical properties of the composite were improved. Compared with pure PLA, the tensile stress of the composite was increased by 116% and the elongation at break was increased by 118%. In summary, this work provides a new strategy for the preparation of PLA/starch composites, which is expected to expand the application of PLA in the packaging field.