有机纤维长度对EPDM绝热层耐烧蚀性能的影响

Effects of organic fiber length on ablation resistance of EPDM insulation

为确定三元乙丙橡胶(EPDM)绝热材料配方中有机纤维长度对绝热层材料烧蚀性能的影响,采用光学显微镜和SEM分别表征混炼后纤维长度和形貌,并采用氧乙炔和高过载模拟烧蚀发动机研究不同长度芳纶纤维(PPTA)和聚酰亚胺纤维(PI)对EPDM绝热材料烧蚀性能影响规律。研究结果表明,混炼后初始长度1~6 mm的PPTA纤维经过混炼后形貌严重破损,长度均在1 mm左右,而PI纤维形貌无明显变化,仅初始长度4~6 mm的PI纤维断裂为2.5~3.5 mm;相同纤维长度下,PI纤维填充绝热层氧乙炔线烧蚀率明显低于PPTA纤维填充绝热层;随着PPTA纤维和PI纤维初始长度的增加,氧乙炔线烧蚀率和高过载模拟烧蚀发动机线烧蚀率降低,且PPTA纤维和PI纤维分别在初始长度4 mm和2 mm处氧乙炔线烧蚀率趋于稳定;1、3和5 mm的PPTA纤维与2~6 mm PI纤维共用填充绝热层氧乙炔线烧蚀率相当,但高过载模拟烧蚀发动机线烧蚀率则随着PI纤维长度的变短而降低,PPTA纤维长度变化对其无明显影响;采用初始长度2~3 mm的PI纤维单独或与一定比例PPTA纤维共用,其耐烧蚀性能最佳。

In order to determine the effect of organic fiber length in EPDM insulation formulation on ablation performance of insulation material, the length and morphology of fibers after calendering were characterized by optical microscope and SEM respectively.The effects of different lengths of aramid fiber(PPTA) and polyimide fiber(PI) on ablation performance of EPDM insulations were studied by using oxyacetylene and high overload ablation experimental motor.The results show that after calendering, the morphology of PPTA fiber with initial length of 1~6 mm are seriously damaged, and the broken fibers are all about 1 mm in length, while the morphology of PI fiber has no obvious change, only PI fiber with initial length of 4~6 mm are broken into 2.5~3.5 mm in length.The oxyacetylene linear ablation rate of PI fibers-filled insulation is obviously lower than that of PPTA fibers-filled insulation at the same fiber length.With the increase of initial length of PPTA fiber and PI fiber, the linear ablation rate of oxyacetylene and high overload ablation experimental motor decreased.And the oxyacetylene linear ablation rate of PPTA fiber and PI fiber tends to be stable at the initial length of 4 mm and 2 mm respectively.The oxyacetylene linear ablation rates of insulation filled with length of 1 mm, 3 mm and 5 mm PPTA fibers and length of 2~6 mm PI fibers is equivalent.However, the linear ablation rate of high overload ablation experimental motor decreased with the shortening of PI fiber length, and the change of PPTA fiber length has no obvious effect on it.When PI fibers with initial length of 2~3 mm are used alone or used with a certain proportion of PPTA fibers, its ablation resistance is the best.