Fuente: Journal of applied polymer Lugar: RESEARCH ARTICLE To obtain PLA/RPHA blends with balanced strength and toughness, P34HB was first cross-linked using the peroxide BIBP, yielding modified P34HB (RPHA) with a controlled cross-linking density. The RPHA was then melt-blended with PLA, during which a multi-epoxy chain extender (ECE) was introduced to enhance the interfacial adhesion. The resulting blend exhibits strong interfacial bonding and an optimal size range for the elastomer dispersed phase.

ABSTRACT
Blending with bio-based elastomers is an effective strategy for toughening polylactic acid (PLA), but it often requires high elastomer loadings (≥ 20 wt%), leading to a severe loss of strength. In this study, a cascade strategy was proposed based on micro-crosslinking synergistic compatibilization to achieve a high strength–toughness balance in PLA with only 10 wt% of poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P34HB). A micro-crosslinked reactive P34HB (RPHA) was first constructed via in situ crosslinking initiated by bis(tert-butylperoxy) diisopropyl benzene (BIBP). It was then melt-blended with PLA and a multi-epoxy chain extender (ECE) to tailor the interfacial adhesion. The resulting PLA/RPHA-0.2 blend exhibits a high fracture energy of 141.8 MJ/m3—more than ten times that of the un-crosslinked counterpart—while maintaining a high yield strength of 55.2 MPa, only 7.7% lower than neat PLA. The micro-crosslinking strategy enables optimized interfacial strength and finely tuned dispersed phase morphology (only 0.3 μm), which synergistically contribute to the superior toughness. This work provides a novel and sustainable approach to fabricating fully bio-based PLA materials with excellent mechanical properties for green packaging applications.