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<p>Polyborosiloxane (PBDMS) exhibits promising potential in the modification of ethylene‑vinyl acetate copolymer (EVA) owing to its unique dynamic B‑O bonds. However, the significant polarity difference between the two components leads to poor compatibility, distinct macroscopic phase separation, and weak interfacial adhesion in PBDMS/EVA blends, resulting in inefficient stress transfer and an inability to fully exploit the energy dissipation and recovery properties of the dynamic bonds. In this work, maleic anhydride‑grafted EVA (EVA‑g‑MAH) was used as a reactive compatibilizer, and PBDMS/EVA blends with EVA‑g‑MAH mass fractions ranging from 0 to 12 wt% were prepared via melt blending. The effects of compatibilizer content on the micromorphology, thermal behavior, interfacial interactions, and mechanical properties of the blends were systematically investigated using scanning electron microscopy, differential scanning calorimetry, Fourier transform infrared spectroscopy, and uniaxial tensile characterization. EVA‑g‑MAH optimizes the interfacial state through strong polar interactions, effectively suppressing macroscopic phase separation, significantly refining the size of the PBDMS dispersed phase, and improving interfacial stress transfer efficiency. With increasing EVA‑g‑MAH content, the crystallization and melting temperatures of the EVA phase decrease overall, while the crystallinity decreases first, then increases, and decreases again. Under the present conditions, at a compatibilizer loading of 9 wt%, the system forms numerous small and imperfect crystals, characterized by high crystallization enthalpy and low melting enthalpy. Shifts in infrared characteristic peaks directly confirm significant molecular chain entanglement and interfacial polar interactions between PBDMS and the EVA matrix. The blends achieve optimal comprehensive mechanical performance at this ratio, with a tensile strength of 15.5&#xa0;MPa (50.7% improvement) and an elongation at break of 399.5% (94.0% improvement) compared with the uncompatibilized system. When the compatibilizer content is further increased to 12 wt%, excessive molecular aggregation occurs at the interface, leading to a slight decrease in tensile strength, although excellent toughness is maintained. EVA‑g‑MAH demonstrates high compatibilizing efficiency for the PBDMS/EVA system, providing a feasible technical route for the development of high‑performance EVA‑based composites used in high‑end sports protective equipment.</p>

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Multiscale structure and properties of EVA-g-MAH compatibilized PBDMS/EVA blends

  • 期刊论文

  • 发表日期：

    2026年6月1日

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  • Zhe Zhai,
  • Feng Li,
  • Qiang Li,
  • Hongyu Liu,
  • Wei Chen

摘要

Polyborosiloxane (PBDMS) exhibits promising potential in the modification of ethylene‑vinyl acetate copolymer (EVA) owing to its unique dynamic B‑O bonds. However, the significant polarity difference between the two components leads to poor compatibility, distinct macroscopic phase separation, and weak interfacial adhesion in PBDMS/EVA blends, resulting in inefficient stress transfer and an inability to fully exploit the energy dissipation and recovery properties of the dynamic bonds. In this work, maleic anhydride‑grafted EVA (EVA‑g‑MAH) was used as a reactive compatibilizer, and PBDMS/EVA blends with EVA‑g‑MAH mass fractions ranging from 0 to 12 wt% were prepared via melt blending. The effects of compatibilizer content on the micromorphology, thermal behavior, interfacial interactions, and mechanical properties of the blends were systematically investigated using scanning electron microscopy, differential scanning calorimetry, Fourier transform infrared spectroscopy, and uniaxial tensile characterization. EVA‑g‑MAH optimizes the interfacial state through strong polar interactions, effectively suppressing macroscopic phase separation, significantly refining the size of the PBDMS dispersed phase, and improving interfacial stress transfer efficiency. With increasing EVA‑g‑MAH content, the crystallization and melting temperatures of the EVA phase decrease overall, while the crystallinity decreases first, then increases, and decreases again. Under the present conditions, at a compatibilizer loading of 9 wt%, the system forms numerous small and imperfect crystals, characterized by high crystallization enthalpy and low melting enthalpy. Shifts in infrared characteristic peaks directly confirm significant molecular chain entanglement and interfacial polar interactions between PBDMS and the EVA matrix. The blends achieve optimal comprehensive mechanical performance at this ratio, with a tensile strength of 15.5 MPa (50.7% improvement) and an elongation at break of 399.5% (94.0% improvement) compared with the uncompatibilized system. When the compatibilizer content is further increased to 12 wt%, excessive molecular aggregation occurs at the interface, leading to a slight decrease in tensile strength, although excellent toughness is maintained. EVA‑g‑MAH demonstrates high compatibilizing efficiency for the PBDMS/EVA system, providing a feasible technical route for the development of high‑performance EVA‑based composites used in high‑end sports protective equipment.