Rubber network microstructure effects on the toughness and transparency of acrylic-modified PMMA

Complementary measurements resolved crosslinker-dependent rubber-core network states. • Rubber-core dynamics tracked mechanical and optical performance in PMMA/AIM. • DAM-based PMMA/AIM composites reached an impact strength of 7.2 kJ m −2 . • DAM-based PMMA/AIM composites retained 89.2% transmittance and 7.5% haze. Balancing toughness and optical transparency in poly(methyl methacrylate)/acrylic impact modifier (PMMA/AIM) composites requires control of the crosslinked rubber-core network. Gel content and equilibrium swelling alone cannot distinguish the dynamic states generated by structurally different crosslinkers. Triallyl cyanurate (TAC), diallyl maleate (DAM), allyl methacrylate (ALMA) and ethylene glycol dimethacrylate (EGDMA) were used to tune poly(butyl acrylate-co-styrene) [P(BA-co-St)] rubber cores. Apparent effective crosslink density ( ν e,app ), swelling kinetics and segmental dynamics were evaluated together with particle size, morphology, grafting and dispersion. Although similar apparent crosslink densities were obtained, different crosslinkers generated distinct diffusion–relaxation behaviors and dynamic mechanical responses. Among the systems tested, DAM-based PMMA/AIM composites provided the most favorable balance, increasing impact strength to 7.2 kJ m −2 while retaining 89.2% transmittance and 7.5% haze. The enhanced segmental relaxation behavior, crosslinker-dependent swelling behavior, and enlarged fracture damage zone collectively indicate that the DAM-derived network promotes crack-tip deformation and deformation-assisted energy dissipation during fracture. These findings demonstrate that crosslinker selection provides an effective strategy for tuning rubber-core network dynamics and optimizing the toughness–transparency balance of impact-modified PMMA within the investigated formulation space. Download: Download high-res image (416KB) Download: Download full-size image