Cellulose is an important part of transformer insulation paper. Thermal aging of cellulose occurs in long-term operation of transformers, which deteriorates the mechanical properties and thermal stability of cellulose, resulting in a decrease in the transformer life. Therefore, improvement of the mechanical properties and thermal stability of cellulose has become a research hotspot. In this study, the effects of different silane coupling agents on the mechanical properties and thermal stability of modified cellulose were studied. The simulation results showed that the mechanical parameters of cellulose are only slightly improved by KH560 (γ-glycidyl ether oxypropyl trimethoxysilane) and KH570 (γ-methylacrylloxy propyl trimethoxy silane) modified nano-SiO₂, while the mechanical parameters of cellulose are greatly improved by KH550 (γ-aminopropyl triethoxy silane) and KH792 (N-(2-aminoethyl)-3-amino propyl trimethoxy silane) modified nano-SiO₂. The glass-transition temperature of the composite model is 24 K higher than that of the unmodified model. The mechanism of the change of the glass-transition temperature was analyzed from the point of view of free-volume theory. The main reason for the change of the glass-transition temperature is that the free volume abruptly changes, which increases the space for movement of the cellulose chain and accelerates the whole movement of the molecular chain. Therefore, modifying cellulose with KH792-modified nano-SiO₂ can significantly enhance the thermal stability of cellulose.

中文翻译：

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硅烷偶联剂接枝纳米SiO 2改性改善绝缘纸纤维素力学性能和热稳定性的分子模拟

纤维素是变压器绝缘纸的重要组成部分。纤维素的热老化发生在变压器的长期运行中，这会使纤维素的机械性能和热稳定性下降，从而导致变压器寿命的缩短。因此，改善纤维素的机械性能和热稳定性已成为研究热点。在这项研究中，研究了不同硅烷偶联剂对改性纤维素的机械性能和热稳定性的影响。模拟结果表明，KH560（γ-缩水甘油醚氧基丙基三甲氧基硅烷）和KH570（γ-甲基丙烯酰氧基丙基三甲氧基硅烷）改性的纳米SiO ₂仅略微改善了纤维素的力学参数。，而KH550（γ-氨基丙基三乙氧基硅烷）和KH792（N-（2-氨基乙基）-3-氨基丙基三甲氧基硅烷）改性的纳米SiO ₂大大改善了纤维素的机械参数。合成模型的玻璃化转变温度比未修改模型的玻璃化转变温度高24K。从自由体积理论的角度分析了玻璃化转变温度变化的机理。玻璃化转变温度改变的主要原因是自由体积突然改变，这增加了纤维素链运动的空间并加速了分子链的整个运动。因此，用KH792改性的纳米SiO ₂改性纤维素 可以显着提高纤维素的热稳定性。