Toughening of Cocontinuous Polylactide/Polyethylene Blends via an Interfacially Percolated Intermediate Phase

• Published in: Macromolecules Vol. 51; no. 10; pp. 3572 - 3581
• Main Authors: Zolali, Ali M, Favis, Basil D
• Format: Journal Article
• Language: English
• Published: American Chemical Society 22.05.2018
• ISSN: 0024-9297; 1520-5835
• DOI: 10.1021/acs.macromol.8b00464

It will be shown that an interfacially percolated rubbery phase in a cocontinuous polylactide (PLA)/linear low-density polyethylene (LLDPE) blend results in a significant increase in the impact strength. All blends possess a tricontinuous phase morphology in which poly­(ε-caprolactone) (PCL), poly­(ethylene–methyl acrylate) (EMA), and ethylene–methyl acrylate–glycidyl methacrylate (EMA-GMA) percolate at the interface of PLA/LLDPE but offer different toughening and compatibilization effects. Among these components, the addition of EMA-GMA to the binary PLA/LLDPE blend reduces the cocontinuous PLA/LLDPE phase thickness from about 25 to 5 μm and yields a very tough material with an impact strength of about 515 J/m, which is approximately 13 times greater than the original cocontinuous PLA/LLDPE blend and more than 32 times that of PLA. The ternary blends show significant improvements in the impact strength within the tricontinuous region; however, the principal differences in the toughening effects are attributed to interfacial interactions between the phases. The interconnected network of the rubbery phase is expected to percolate the stress field throughout the tricontinuous system and reduce the detrimental dilatational stress in the bulk blend.