Fushe yanjiu yu fushe gongyi xuebao (Dec 2022)
Hexagonal boron nitride/acrylic rubber composites: preparation, thermal and mechanical properties, and effect of γ-radiation
Abstract
The development of heat- and radiation-resistant rubber composite materials is a key future research direction for advanced rubber materials. In this work, raw acrylic rubber (ACM) prepared via emulsion polymerization was first melt-blended with hexagonal boron nitrite (BN) particles with average particle sizes of 0.25 μm, 1.00 μm, and 10.00 μm (which were correspondingly labeled as BN-0.25, BN-1, and BN-10) and then in situ cured to obtain a variety of BN/ACM composites. The effects of mass fraction and particle sizes of BN fillers, as well as γ radiation on thermal stability, conductivity, electrical resistivity, and mechanical properties of BN/ACM composites were investigated. The results showed that when the mass fraction of BN was less than 40%, the thermal stability, conductivity, and electrical resistivity of BN/ACM composites increased with mass fraction and particle sizes of BN. At a mass fraction of BN-10 of 40%, the thermal conductivity of BN-10/ACM composites was as high as 1.438 W/(m·K), which exceeds that for high thermal conductivity polymer materials (>1 W/(m·K)). The mechanical properties, such as tensile strength and elongation at break, also increased with the increase of the mass fraction and the decrease of the particle sizes of BN. When the mass fraction of BN reached 40%, the overall mechanical properties of composites worsened due to the agglomeration of BN particles. The γ radiation effect on ACM and BN/ACM composites was studied. The results showed that when the absorbed dose reached 200 kGy, the thermal stability and conductivity of ACM and BN/ACM composites were improved, while electrical resistivity slightly decreased. Pure ACM matrix showed a tendency of hardening under γ radiation through crosslinking, resulting in decreased tensile strength of BN/ACM composites. However, the tensile strength and elongation at a break of the BN/ACM composites irradiated by γ-ray remained as high as those of the pure ACM, when the mass fraction of BN was less than 20%. Our results indicated that a BN particle size of 10 μm and mass fraction of 30% were optimal in the preparation of BN/ACM composites with a good radiation resistance and high thermal conductivity. This work provides theoretical and experimental guidance for the development of ACM composites with high thermal conductivity and radiation resistance for high-temperature oil seals, thermal interface materials for electronic components and high-energy radiation environment.
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