Synergistic effects of polyethylene glycol and organic montmorillonite on the plasticization and enhancement of poly(lactic acid)

ABSTRACT Poly(lactic acid) (PLA)/polyethylene glycol (PEG)/organic montmorillonite (OMMT) composites were prepared by melt blending, and their mechanical, rheological behavior, crystalline behavior, and thermal stability were investigated. Results showed that the elongation‐at‐break and notch‐impact strength of PLA/15PEG/1.5OMMT were 466.45% and 4.34 kJ m −2 , respectively, which were nearly 42 and 2 times higher than those of PLA, respectively. The elongation‐at‐break of PLA/15PEG/1.5OMMT was also 33 times higher than that of PLA/15PEG and 30 times that of PLA/1.5OMMT. With addition of PEG, PLA chains could insert to OMMT effectively and increase the layer space of OMMT. The characteristics of dynamic behavior and fracture morphology showed that the plasticizer PEG could soften the PLA matrix, leading to easy plastic deformation. OMMT was well distributed in the PLA matrix and able to transfer the stress of external forces, thereby contributing to the matrix yielding initiation and expansion of polymer composites. The synergistic effect of OMMT and PEG was determined by studying the mechanical properties of PLA/PEG/OMMT composite. Differential scanning calorimetry and thermogravimetry studies revealed that OMMT as a nucleating agent improved crystallization and thermal stability. Thus, the synergistic effect of OMMT and PEG balanced the stiffness and toughness of PLA. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136 , 47576.