Key Laboratory of Engineering Dielectrics and Its Application, Ministry of Education, School of Electrical and Electronic Engineering, Harbin University of Science and Technology, Harbin 150080, China.
Molecules. 2020 Jul 8;25(14):3117. doi: 10.3390/molecules25143117.
In order to improve the mechanical and dielectric properties of radome cyanate, a synergistic reinforcement method is employed to develop a resin-based ternary-composite with high heat-resistance and preferable radar-band transmission, which is expected to be applied to fabricate radomes capable of resisting high temperature and strong electric field. According to copolymerization characteristics and self-curing mechanism, epoxy resin (EP) and bismaleimide (BMI) are employed as reinforcements mixed into a cyanate ester (CE) matrix to prepare CE/BMI/EP composites of a heat-resistant radome material by high-temperature viscous-flow blending methods under the catalysis of aluminum acetylpyruvate. The crystallization temperature, transition heat, and reaction rate of cured polymers were tested to analyze heat-resistance characteristics and evaluate material synthesis processes. Scanning electron microscopy was used to characterize the micro-morphology of tensile fracture, which was combined with the tensile strength test and dynamic thermomechanical analysis to investigate the composite modifications on tenacity and rigidity. Weibull statistics were performed to analyze the experimental results of the dielectric breakdown field, and the dielectric-polarization and wave-transmission performances were investigated according to alternative current dielectric spectra. Compared with the pure CE and the CE composites individually reinforced by EP or BMI, the CE/BMI/EP composite acquires the most significant amelioration in both the mechanical and electrical insulation performances as indicated by the breaking elongation and dielectric breakdown strength being simultaneously improved by 40%, which are consistently manifested by the obviously increased transverse lines uniformly distributed on the fracture cross-section. Furthermore, the glass-transition temperature of CE/BMI/EP composite reaches the highest values of nearly 300 °C, with the relative dielectric constant and dielectric loss being mostly reduced to less than 3.2 and 0.01, respectively. The experimental results demonstrate that the CE/BMI/EP composite is a highly-qualified wave-transmission material with preferences in mechanical, thermostability, and electrical insulation performances, suggesting its prospective applications in low-frequency transmittance radomes.
为了提高雷达罩氰酸酯的力学和介电性能，采用协同增强的方法，开发了一种具有高热阻和良好雷达波段传输性能的树脂基三元复合材料，有望用于制造能够耐受高温和强电场的雷达罩。根据共聚特性和自固化机理，选用环氧树脂（EP）和双马来酰亚胺（BMI）作为增强体，混合到氰酸酯（CE）基体中，在乙酰丙酮铝的催化作用下，通过高温粘性流混合方法制备耐热雷达罩用 CE/BMI/EP 复合材料。测试了固化聚合物的结晶温度、转变热和反应速率，以分析耐热特性并评估材料合成工艺。扫描电子显微镜用于表征拉伸断裂的微观形貌，结合拉伸强度试验和动态热机械分析研究了韧性和刚性的复合材料改性。对介电击穿场的实验结果进行了威布尔统计分析，并根据交流介电谱研究了介电极化和波传输性能。与纯 CE 和单独用 EP 或 BMI 增强的 CE 复合材料相比，CE/BMI/EP 复合材料在力学和电绝缘性能方面均获得了最显著的改善，断裂伸长率和介电击穿强度同时提高了 40%，这一点在断裂横截面上均匀分布的横向线明显增加上得到了一致体现。此外，CE/BMI/EP 复合材料的玻璃化转变温度达到近 300°C 的最高值，相对介电常数和介电损耗大多降低到 3.2 以下和 0.01 以下。实验结果表明，CE/BMI/EP 复合材料是一种机械性能、热稳定性和电绝缘性能优异的优质波传输材料，有望在低频透波雷达罩中得到应用。
