太阳辐照对芳纶纤维及其复合材料性能的影响

Effect of solar radiation on the properties of aramid fibers and composites

选择K49和F-Ⅲ两种芳纶纤维及其5224A环氧树脂基复合材料为研究对象,以单丝拉伸强度、FTIR、DSC、SEM、复合材料力学性能和介电性能作为表征手段,研究太阳辐照对芳纶纤维的结构性能以及芳纶/环氧复合材料的结构透波性能的影响作用。结果表明:K49在辐照过程中表现出显著的自我屏蔽效应,400h的强度保持率为82%,F-Ⅲ未观察到明显的自我屏蔽效应,强度保持率为50%。辐照前后的FTIR,XPS,DSC,SEM结果证明纤维表层出现了降解,氢键破坏与结晶度下降是引起纤维性能下降的主要原因。太阳辐照前后复合材料的性能测试结果证明辐照对材料的性能无明显影响,辐照后复合材料的弯曲、层间剪切和介电性能基本无变化,拉伸强度略有升高,压缩强度轻微下降,K49/5224A的压缩强度下降了11.8%,F-Ⅲ/5224A的压缩强度下降了6.6%,这主要是由于太阳辐照老化仅引起复合材料表面树脂基体轻微降解所造成的。

K49 and F-Ⅲtwo kinds of different structure aramid fibers and their 5224A epoxy matrix composites were selected.The tension strength of single fiber,FTIR,XPS,DSC,SEM,mechanical and dielectrical properties was used to characterize the physicochemical properties of fibers and structure/wave-transmitting properties of composites.It is found that different fibers result in different changes under the same solar radiation condition.The obvious“self-shield”phenomenon is observed in K49 fibers,but there’s no proof that F-Ⅲhas the same ability.A tension strength conservation rate of 82%is obtained after 400 hours solar radiation.F-Ⅲfibers,by contrast,are sensitive to solar radiation and a conservation rate of 50%is obtained at the same condition.The decreased tension strength is due to physicochemical degradation on the surface of the fibers and the decrease of crystallinity degree.It is proved that solar radiation has no obvious effect on the properties of composites.The flexibility,ILSS and dielectric properties has little change.The tensile strength is slightly improved,and the compression strength is slightly decreased.A decrease of 11.8%is obse-rved on K49/5224A composites and 6.6%for that of F-Ⅲ/5224A.It is because of that the degrad-ation occurred on the surface of composites.