Enhanced foaming performance of crosslinked poly(3-hydroxybutyrate-co-4-hydroxybutyrate)/poly(butylene adipate-co-terephthalate) blends via reactive chain extension

This study investigates the enhanced foaming behavior of partially crosslinked blends of poly(3-hydroxybutyrate-co-4-hydroxybutyrate) [P(3HB-co-4HB)] with poly(butylene adipate-co-terephthalate) (PBAT) using a reactive modification strategy. The crosslinking process employed di-(tert-butylperoxyisopropyl)benzene (DTBPIB) as a radical initiator and triallyl isocyanurate (TAIC) as a coagent. The effects of varying TAIC content on gel fraction, rheological behavior, mechanical properties, and cellular morphology were systematically studied. The modified blends demonstrated significantly increased gel content and complex viscosity, particularly at low angular frequencies, indicating enhanced melt elasticity. Tensile tests revealed improved modulus and strength with increasing TAIC loading, suggesting network formation within the matrix. The foamed structures, prepared using a chemical blowing agent, exhibited higher expansion ratios and finer, more uniform cell morphologies in samples with both DTBPIB and TAIC. These results demonstrate that reactive crosslinking offers a promising route to engineer bio-based foams with improved mechanical integrity and foamability.