In this paper, we report the study of degradation for a kind of ideal mandrel material called poly-α-methylstyrene based on theoretical and experimental methods. First-principles calculations reveal two types of process: depolymerization and hydrogen-transfer-induced chain scission. The energy barrier for the former (0.68–0.82 eV) is smaller than that for most of the latter (1.39–4.23 eV). More importantly, reaction rates suggest that the former is fast whereas the latter is mostly slow, which can result in a difference of 5–31 orders of magnitude at 550 K. Furthermore, a thermogravimetric experiment shows that the activation energy of 2.53 eV for degradation is between those of fast and slow processes, corresponding to the theoretical average value of multiple reaction paths. Thus, a mandrel degradation model combining fast and slow processes is established at the atomic level. Our work provides a direction for research into the key technology of target fabrication in inertial confinement fusion.

中文翻译：

---

组合快慢过程的芯轴退化模型

在本文中，我们报告了一种基于理论和实验方法的理想芯棒材料聚-α-甲基苯乙烯的降解研究。第一性原理计算揭示了两种类型的过程：解聚和氢转移诱导的断链。前者的能垒（0.68-0.82 eV）小于后者的大部分能垒（1.39-4.23 eV）。更重要的是，反应速率表明前者快而后者大多慢，这可能导致在 550 K 时相差 5-31 个数量级。此外，热重实验表明，降解的活化能为 2.53 eV介于快与慢过程之间，对应于多个反应路径的理论平均值。因此，在原子水平上建立了结合快速和慢速过程的芯轴退化模型。我们的工作为惯性约束聚变靶制造关键技术的研究提供了方向。