Effect of Dicumyl Peroxide on the Interfacial Structure, Crystallization Behavior, and Properties of PBAT / PHBH Blends

ABSTRACT

The poor interfacial compatibility between PBAT and PHBH limits the mechanical properties of their blends, restricting their potential use in biodegradable packaging applications. In this study, dicumyl peroxide (DCP) was used as a reactive compatibilizer to modify PBAT/PHBH (50/50, wt/wt) blends, and the effects of DCP content on the interfacial interaction, melt rheology, phase morphology, crystallization behavior, mechanical and barrier properties were systematically investigated. FTIR, dynamic mechanical analysis, and rheological measurements indicated enhanced interactions between PBAT and PHBH after DCP addition, accompanied by restricted molecular relaxation and increased melt elasticity. SEM observations showed that the dispersed PHBH domains were progressively refined and the interfacial boundaries became less distinct with increasing DCP content, indicating improved interfacial adhesion. DSC and polarized optical microscopy revealed that DCP modified the crystallization behavior of both components, particularly promoting PHBH crystallization while slightly suppressing PBAT crystallization. The improved interfacial adhesion and refined phase morphology enhanced stress transfer between the two phases, resulting in a substantial improvement in tensile properties. At 0.1 wt% DCP, the tensile strength increased from 13.56 to 39.29 MPa, while the elongation at break increased from 17.47% to 841.33%. Further increasing the DCP content to 0.2 wt% resulted in a decrease in tensile properties, probably due to excessive radical‐induced reactions and the resulting restriction of molecular mobility. In contrast, the barrier properties were only slightly affected, with WVP and OP remaining within 1.04–1.11 × 10 ⁻¹³  g cm·(cm ²  s Pa) ⁻¹ and 3.58–4.04 × 10 ⁻¹¹  cm ³  cm cm ⁻²  s ⁻¹  cmHg ⁻¹ , respectively, after DCP addition. Overall, 0.1 wt% DCP provided the best balance between interfacial structure, mechanical and barrier properties, demonstrating the potential of reactive compatibilization for developing high‐performance biodegradable PBAT/PHBH packaging materials.