退役光伏组件TPT背板热氧化降解特性研究

doi:10.11949/0438-1157.20251307

摘要/Abstract

摘要：

针对退役晶硅光伏组件中的TPT背板在空气氛围下开展热重-红外光谱分析与反应力场分子动力学（ReaxFF-MD）模拟计算，系统探讨了TPT背板的热解反应行为、动力学特征与热解机理。热重实验表明，TPT背板在空气中的热氧化降解为双阶段反应，呈现出较氮气更低的热解起始温度（280 ℃）和更高的热解终止温度（585 ℃）。动力学分析显示两个阶段的平均活化能分别为185和128 kJ/mol。ReaxFF-MD模拟揭示，空气氛围下，氧气主要通过强化碳骨架断裂和氢脱除过程加速聚合物降解，而对脱氟过程的影响较小。TPT的热解由烷氧（C-O）键断裂引发，氧气通过生成过氧自由基参与反应链延伸，促进了含氧小分子如CO₂、甲醇、甲醛、乙醛等的生成。此外，对苯二甲酸等产物数量亦有增加。研究结果为理解氧气参与下TPT背板的热解过程提供了理论支持。

关键词: 退役晶硅光伏组件, TPT背板, 热解, 动力学, 分子模拟, ReaxFF-MD

Abstract:

The thermal degradation behavior of the TPT backsheet from end‑of‑life crystalline silicon photovoltaic (EoL c-Si PV) modules was systematically investigated under an air atmosphere by means of thermogravimetry‑infrared (TG‑IR) analysis and reactive force field molecular dynamics (ReaxFF‑MD) simulations. The thermogravimetric experiment results show that the oxidative degradation of TPT in air proceeds in two distinct stages, exhibiting a lower onset temperature (280 °C) and a higher termination temperature (585 °C) compared with nitrogen conditions. Kinetic analysis yields average activation energies of 185  kJ/mol for the first stage and 128 kJ/mol for the second stage. The ReaxFF‑MD simulations reveal that under air, oxygen predominantly accelerates polymer degradation by reinforcing carbon‑backbone scission and hydrogen removal processes, while exerting a comparatively minor influence on defluorination. The pyrolysis of TPT is initiated by cleavage of alkoxy (C-O) bonds. Subsequently, oxygen participates in chain‑propagation via peroxy radicals, thereby promoting the formation of oxygenated small molecules such as CO₂, methanol, formaldehyde and acetaldehyde. Moreover, an increased yield of terephthalic acid and related aromatic products is observed. These results provide a theoretical basis for understanding the oxidative pyrolysis process of TPT backsheets in oxygen‑rich atmospheres.

Key words: EoL c-Si PV modules, TPT backsheet, pyrolysis, kinetics, molecular simulation, ReaxFF-MD

中图分类号:

X705

王上铭, 李小峰, 方秋宇, 王强, 张国平, 陈渝楠, 陈斌. 退役光伏组件TPT背板热氧化降解特性研究[J]. 化工学报, DOI: 10.11949/0438-1157.20251307.

Shangming WANG, Xiaofeng LI, Qiuyu FANG, Qiang WANG, Guoping ZHANG, Yunan CHEN, Bin CHEN. Thermo-oxidative degradation characteristics of TPT backsheet from end-of-life photovoltaic modules[J]. CIESC Journal, DOI: 10.11949/0438-1157.20251307.

图/表 10

图1 TPT的MD计算模型

Fig. 1 The MD calculation model of TPT

图2 力场对于TPT体系的适用与准确性验证

Fig. 2 Validation of the applicability and accuracy of the force field for TPT system

图3 TPT在空气氛围下的热重特性

Fig. 3 Thermogravimetric characteristics of TPT in air atmosphere

图4 空气氛围下不同方法所得的TPT背板Ea值

Fig. 4 The Ea values of TPT backsheet obtained by different methods in air atmosphere

图5 不同氛围下TPT的热解行为对比

Fig. 5 Comparison of the pyrolysis behavior of TPT under different atmospheres

图6 TPT在空气氛围下的TG-IR谱图

Fig. 6 The TG-IR spectrum of TPT under air atmosphere

图7 不同氛围下TPT模拟体系物种数量与分子数量变化

Fig. 7 The changes in the number of species and molecules in the TPT simulation system under different atmospheres

图8 TPT在氮气和空气氛围中的产物分布

Fig. 8 The product distribution of TPT under nitrogen and air atmospheres

图9 TPT在不同氛围中主要化学键的时序变化

Fig. 9 The temporal changes of the main chemical bonds in TPT under different atmospheres

图10 TPT在空气氛围中的热解机理

Fig. 10 The thermal decomposition mechanism of TPT under air atmosphere

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