石英纤维/KH308复合材料的介电性能

为研究石英纤维/聚酰亚胺（KH308）复合材料介电性能与纤维体积分数、频率、温度和吸水率之间的关系，通过热压成型法，制备了4种不同纤维体积含量的石英纤维/KH308复合材料，采用高Q谐腔法分别测试这4种复合材料在不同状态下的介电常数和介电损耗。结果表明：石英纤维/KH308复合材料的介电常数随着纤维体积分数增加而变大，介电损耗随纤维体积分数变化不大；7~18 GHz频率下，复合材料的介电常数和介电损耗基本不随频率变化；25~300℃下，复合材料的介电常数随温度增加变化比较平缓，而介电损耗随温度的增加而降低；复合材料吸水后，介电常数和介电损耗都会增加；复合材料介电常数ε<4，介电损耗tanδ<0.1，能满足导弹天线罩透波材料介电性能的要求。

Dielectric properties of quartz fiber reinforced KH308 composites

In order to investigate the relationship between dielectric properties of quartz fiber/polyimide (KH308) composites and fiber volume fraction of composites, frequency, temperature and water absorption, four kinds of quartz fiber reinforced KH308 composites with different fiber volume fractions were prepared by hot pressing technology. Dielectric constant and dielectric loss of these composites were characterized by high Q resonance cavity method in different conditions. The results show that dielectric constant of quartz fiber/KH308 composites increases with increasing fiber content, and the dielectric loss basically does not vary with fiber content. At 7-18 GHz, dielectric constant and dielectric loss of the composites do not vary with frequency. The dielectric constant increases with temperature slowly, while the dielectric loss decreases with increasing temperature at 25-300℃. Dielectric constant and dielectric loss of the composites increase with water content. Fiber/KH308 composites with low dielectric constant (ε<4) and low dielectric loss (tanδ<0.1), can satisfy the requirements of dielectric properties of the missile radome wave-transparent materials.