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首页> 外文会议>Photonics for Space Environments XI >Polyhedral Oligomeric Silsesquioxane (POSS) Polyimides as Space-Survivable Materials
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Polyhedral Oligomeric Silsesquioxane (POSS) Polyimides as Space-Survivable Materials

机译：多面体低聚倍半硅氧烷（POSS）聚酰亚胺作为空间可生存材料

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Polyimides (PIs) such as Kapton~® are used extensively in spacecraft thermal blankets, solar arrays, and space inflatable structures. Atomic oxygen (AO) in low Earth orbit (LEO) causes severe degradation of Kapton~®. SiO_2 coatings impart remarkable oxidation resistance and have been widely used to protect Kapton~®, yet imperfections in the SiO_2 application process and micrometeoroid/debris impact in orbit damage the SiO_2 coating leading to Kapton~® erosion. A polyimide that is self-passivating by the formation of a silica layer upon exposure to AO has been achieved by the copolymerization of a polyhedral oligomeric silsesquioxane (POSS) diamine with the Kapton~® monomers, pyromellitic dianhydride and 4,4'-oxydianiline, resulting in POSS-Kapton~®-polyimide. The self-passivating properties have been shown by monitoring a 1 micron deep scratch in POSS-PIs after exposure to AO. Kapton H~®, SiO_2-coated Kapton HN~®, and 8.75 weight % Si_8O_(11) cage "main-chain" POSS-polyimide (8.75 wt % Si_8O_(11) MC-POSS-PI) were exposed to equivalent AO fluences before and after being scratched. During the first AO exposure and outside of the scratch, these samples eroded 5.0 microns, 0 microns, and less than 200 nm respectively. During the second AO exposure, the samples eroded an additional 5.0 microns within the scratch and outside of the scratch, 7.0 microns within the scratch and 0 microns outside of the scratch, and 200 nm within the scratch and 0 microns outside of the scratch respectively. Surface analysis of MC-POSS-PI films exposed to a hyperthermal O-atom beam shows evidence for the formation of a SiO_2 passivation layer upon AO exposure. This is exemplified by erosion yields of 3.5 and 7 wt % Si_8O_(11) MC-POSS-PI samples which were 3.7 and 0.98 percent, respectively, of the erosion yield for Kapton H~® at a fluence of 8.5 x 10~(20) O atoms cm~(-2). Comparison of MC-POSS-PIs and "side-chain" POSS-PI (SC-POSS-PI) shows that these polymers have similar resistance to atomic oxygen and physical properties similar to Kapton H~®. Erosion yields and imaging of POSS-PIs flown on MISSE1, in a sample tray exposed to all elements (AO, UV light) of the space environment, demonstrated the greatly extended lifetime of POSS-PIs over polyimide.
机译：聚酰亚胺（PI），例如Kapton®®广泛用于航天器的隔热毯，太阳能电池板和太空可充气结构中。低地球轨道（LEO）中的原子氧（AO）导致Kapton〜®严重降解。 SiO_2涂层具有出色的抗氧化性，已被广泛用于保护Kapton〜®，但是SiO_2涂覆过程中的缺陷以及轨道上的微流星体/碎屑撞击会损坏SiO_2涂层，从而导致Kapton〜®腐蚀。多面体低聚倍半硅氧烷（POSS）二胺与Kapton®单体，均苯四酸二酐和4,4'-氧二苯胺的共聚反应可实现一种通过在暴露于AO时形成二氧化硅层而自钝化的聚酰亚胺。产生POSS-Kapton〜-聚酰亚胺。通过监测暴露于AO后的POSS-PI中1微米深的划痕，可以显示出自钝化性能。将Kapton H〜®，涂覆SiO_2的Kapton HN〜®和8.75 wt％的Si_8O_（11）笼状“主链” POSS聚酰亚胺（8.75 wt％的Si_8O_（11）MC-POSS-PI）暴露于等效的AO通量被划伤之前和之后。在第一次AO曝光期间和在划痕外部，这些样品分别腐蚀了5.0微米，0微米和小于200 nm。在第二次AO曝光期间，样品分别在划痕和划痕外部另外腐蚀了5.0微米，在划痕内部腐蚀了7.0微米，在划痕外部腐蚀了0微米，在划痕内部腐蚀了200纳米，在腐蚀作用外部腐蚀了0微米。暴露于高温O原子束的MC-POSS-PI膜的表面分析表明，在AO暴露后会形成SiO_2钝化层。以3.5和7 wt％的Si_8O_（11）MC-POSS-PI样品的腐蚀产率为例，在8.5 x 10〜（20）的通量下，Kapton H〜®的腐蚀产率分别为3.7和0.98％。 ）O原子cm〜（-2）。 MC-POSS-PI和“侧链” POSS-PI（SC-POSS-PI）的比较显示，这些聚合物具有与Kapton H〜®类似的对原子氧的抗性和物理性质。在暴露于太空环境中所有元素（AO，紫外线）的样品盘中，MISSE1上流失的POSS-PIs的腐蚀率和成像结果表明，POSS-PIs的使用寿命大大超过了聚酰亚胺。

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