Morphological control and interfacial compatibilization of fully biobased PLA/ENR blends via partial crosslinking ENR with sebacic acid

The fully biobased polylactide/epoxidized natural rubber (PLA/ENR) blend usually shows poor mechanical properties due to the coarse phase-separated morphology with low interfacial adhesion. Herein, we report a novel strategy to tailor the phase morphology and interfacial adhesion of PLA/ENR blend by partial crosslinking ENR with sebacic acid (SA). A series of partially crosslinked sebacic acid modified ENRs (mENRs) with different crosslinking degrees combining with reactive epoxy and carboxyl groups were simply prepared by mixing ENR with SA with 1-methylimidazole as a catalyst. In-situ interfacial compatibilization occurs during melt blending PLA with mENR through reaction between reactive groups of mENR and PLA. The phase morphology especially particle diameter and size distribution of dispersed mENR phase can be regulated by the crosslinking degree of mENR. The morphology and interface of PLA/mENR (80/20, w/w) were tuned finely when mENR-1 (SA/ ENR=1/100, mol/mol) with gel fraction of 51% was used to blend with PLA, thus leading to drastically enhanced toughness with impact strength, elongation at break, and tensile toughness of 477.6 J m(-1), 427% and 100.3 MJ m(-3), which were -13.8, -35.6, and -18.9 times higher than those of neat PLA, respectively. The highly-toughened PLA/mENR blend follows a toughening mechanism of internal mENR cavitation induced matrix shear yielding and plastic deformation.

Automated summary

This study presents a novel strategy to tailor the phase morphology and interfacial adhesion of the PLA/ENR blend by partially crosslinking ENR with sebacic acid. The partially crosslinked sebacic acid modified ENRs (mENRs) were prepared by mixing ENR with SA and a catalyst. The phase morphology and interfacial adhesion of the PLA/mENR blend were finely tuned by adjusting the crosslinking degree of mENR. The resulting PLA/mENR blend exhibited drastically enhanced toughness compared to neat PLA, following a toughening mechanism of internal mENR cavitation-induced matrix shear yielding and plastic deformation.