湿热环境对PMI泡沫夹芯复合材料性能的影响

Effects of hydrothermal condition on properties of polymethacrylimide(PMI) foam cored sandwich structure

采用聚甲基丙烯酰亚胺(PMI)泡沫、碳纤维增强环氧树脂(EW220/5258)复合材料面板制备了PMI泡沫夹芯复合材料,研究了PMI泡沫夹芯复合材料、EW220/5258复合材料面板及PMI泡沫芯材的吸湿特性,并讨论了湿热对PMI泡沫夹芯复合材料的压缩性能及介电性能的影响。结果发现:PMI泡沫夹芯复合材料的饱和吸湿时间为96h,饱和吸湿率为1.7%,EW220/5258复合材料面板会对PMI泡沫芯材起到一定的保护作用,阻止水汽进入泡沫,提高PMI泡沫夹芯复合材料的耐湿热性;由于水分子的增塑作用,湿热处理后PMI泡沫夹芯复合材料的压缩强度有所下降,强度保持率约为65.87%,湿热处理初期对其影响较大;湿热处理后,在7～18GHz的测试范围内,PMI泡沫夹芯复合材料的损耗角正切从0.008上升到0.012,介电常数几乎不变。

The polymethacrylimide（PMI） foam cored sandwich structure was prepared by using PMI foam,carbon fiber/epoxy resin（EW220/5258）composites panel.The absorption curves of PMI foam cored sandwich structure,EW220/5258 composite panel and PMI foam were investigated,and the effect of the hydrothermal condition on the compressive and dielectric properties of the PMI foam cored sandwich structure was also determined.The results indicate that the saturated hygroscopic time of the PMI foam cored sandwich structure is 96 hours and its absorption ratio is 1.7%,the EW220/5258 composite panel can protect its PMI foam from water to improve its hydrothermal resistance.Due to the plasticization of water,the compressive strength of the PMI foam cored sandwich structure decreases in hydrothermal environment with the retention ratio of 65.87%.Additionally,the initial stage has more influences on the properties than other stages of hydrothermal treatment.After hydrothermal treatment,the loss tangent of the PMI foam cored sandwich structure increases from 0.008 to 0.012 within the range of 7~18 GHz,while the dielectric constant is almost unchanged.