Preparation And Properties Of KH-SiO₂/PES/MBMI-EPN Composites

Bismaleimide（MBMI）and phenolic epoxy resin（EPN）have good electrical insulation and processing fluidity,but the poor mechanical properties of crosslinking cured material limit the development and application of MBMI and EPN.In this paper,KH-SiO₂/PES/MBMI-EPN composites had been prepared and studied,which bismaleimide-phenolic epoxy resin（MBMI-EPN）,polyethersulfone（PES）,and functionalized nano SiO₂（KH-SiO₂）were used as the matrix,the toughening agent,and the modifier,respectively.The curing kinetics of the resin system was studied by the non-isothermal differential scanning calorimetry and the optimum curing process was deduced,which was 120℃/1 h,+150℃/1 h,+180℃/1 h,+200℃/2 h,+230℃/1 h.The apparent activation energy of the resin system was calculated by Kissinger method and Ozawa method,which was 96.03 kJ/mol and 99.18 kJ/mol,respectively.The average activation energy was 97.61 kJ/mol.The results of Fourier transform infrared spectroscopy（FT-IR）showed that the unsaturated double bond in MBMI resin and the epoxy group in EPN resin were substantially eliminated,and a chemical reaction occurred.PES resin and KH-SiO₂ did not participate in the reaction of resin system but existed in a multi-phase structure through interface interaction.The results of scanning electron microscopy（SEM）indicated that PES resin and KH-SiO₂ had good compatibility in the resin matrix and formed a multi-phase structure,and the interfaces were stable.The properties of KH-SiO₂/PES/MBMI-EPN composites revealed that PES resin and KH-SiO₂ had good synergistic effect and could significantly improve the comprehensive properties of the composites.When the content of PES resin was 4wt%and KH-SiO₂ was 1.5 wt%,bending strength and impact strength of the composites were 156.23 MPa and 20.89 kJ/m²,which were 49.7%and 82.8%higher than those of resin matrix,respectively.And the thermal decomposition temperature of the composites was 393.1℃and was 15℃higher than that of resin matrix.Furthermore,the dielectric constant and dielectric loss of the composites reached 4.55 and 0.0029 at 10 Hz,respectively.The volume resistivity and breakdown strength were 1.74×10¹⁴Ω·m and 29.11 kV/mm,respectively,which were68.3%and 35.9%higher than those of resin matrix.