Preparation and characterization of poly (lactic acid)/saponite grafted poly (methyl methacrylate) nanocomposites and its effect on crystallization via in-situ rheology and FT-IR

In this work, the thiol-ene click chemistry method was successfully used to synthesize saponite grafted poly (methyl methacrylate), namely g-Sap@PMMA. The optimum reaction parameters of g-Sap@PMMA were sifted via orthogonal experiments and range analysis as follows: the mass ratio of g-Sap, 2, 2’-azobis (2-methylpropionitrile), and tetramethylammonium fluoride of 0.5: 0.03: 0.4, the reaction time of 10 h and the reaction temperature of 60 °C. Moreover, poly (L-lactide) (PLA) based nanocomposites were prepared with g-Sap@PMMA as fillers by melt intercalation. Subsequently, the mechanical and rheological properties of PLA/g-Sap@PMMA nanocomposites were investigated, which confirmed that 0.5 wt% g-Sap@PMMA as a critical addition improved the impact strength and elongation at break of PLA/g-Sap@PMMA nanocomposites to 16.0 kJ/m2 and 64.3%, respectively. In addition, the crystallization behavior of PLA/g-Sap@PMMA nanocomposites were soundly explored with the Rheonaut technology. The analysis of characteristic carbonyl group and corresponding storage modulus demonstrated that g-Sap@PMMA facilitated the non-isothermal crystallization kinetics of PLA. Meanwhile, isothermal crystallization showed that half crystallization time of PLA/g-Sap@PMMA (0.5 wt%) nanocomposites were decreased to 28.1 min compared with pure PLA (66.9 min). Finally, the screw shear induces crystallization results showed that the addition of g-Sap@PMMA could actually accelerate the crystallization behavior of PLA in real production environment.