Simulation of Thermodynamic Properties of Aramid/Functionalized Carbon Nanotubes Composites Based on Molecular Dynamics
Zhang Wenqi1,2, Fan Xiaozhou2, Li Yuxuan2, Yu Xiang1, Lü Fangcheng1,2
1. College of Electrical and Electronic Engineering North China Electric Power University Beijing 102206 China; 2. Hebei Key Laboratory of Power Transmission Equipment Security Defense North China Electric Power University Baoding 071003 China
Abstract：Para-aramid paper based materials are widely used in the field of electrical insulation because of their excellent dielectric and mechanical properties. However, pure para-aramid materials have poor thermal conductivity, which cannot dissipate the heat generated in the operation of electrical equipment in time. Recently, researchers have doped nanoparticles into para-aramid fiber to improve its thermal conductivity, and carbon nanotubes (CNT) have attracted much attention for the excellent thermal conductivity and mechanical properties, but there are few reports on the properties of functional carbon nanotubes doped para-aramid composite system. This paper constructs the models of pure para-aramid, non-functionalized, hydroxylated, carboxylated and aminated carbon nanotube-doped aramid composites. Materials Studio and LAMMPS were used for molecular dynamics simulation to obtain the thermal conductivity, glass transition temperature, mechanical properties and structural parameters. The properties of different material systems are analyzed and the mechanism explanation is provided from the molecular level. Firstly, NEMD simulation was carried out in LAMMPS to calculate the thermal conductivity. The thermal conductivity of arylon composites doped with carbon nanotubes was significantly improved, among which the thermal conductivity of PPTA/CNT—COOH had the greatest change, and was increased by 75.2% compared with pure PPTA molecules, PPTA/CNT—OH and PPTA/CNT—NH2 were increased by 70.1% and 63.2% respectively. Then, the glass transition temperatures (Tg) of different material models were obtained by specific volume-temperature curve method. The Tg of PPTA/CNT—COOH increased by 43.29 K, and the Tg of PPTA/CNT, PPTA/CNT—NH2 and PPTA/CNT—OH increased by 27.03 K, 35.52 K and 39.74 K, respectively. In the calculation of mechanical properties, the static constant strain method is used to press a certain direction of stress on the surface of the material, and Young's modulus E and shear modulus G are solved by the obtained stiffness matrix. The results show that the doping of carbon nanotubes can enhance the elastic modulus of composites by more than 30% and shear modulus by more than 15%, among which the mechanical properties of PPTA/CNT—COOH are enhanced most obviously, and the damage effect of temperature rise on mechanical properties is reduced to a certain extent. In the calculation of structural parameters, the FFV, MSD and the number of hydrogen bonds were calculated respectively, and the reasons for the changes in the above thermodynamic properties were explained from the perspective of intermolecular interaction and molecular chain movement. On the one hand, carbon nanotubes have excellent thermal conductivity and mechanical properties, and doping can promote the performance improvement of the composite system by enhancing the strength of the matrix network skeleton. On the other hand, hydrogen bonds were formed between the functionalized carbon nanotubes and aramid molecules, which enhanced the interaction between molecules and formed a stronger molecular network, and improved the stability of the system. Due to the difference of electronegativity of N and O and the number of grafts, there are PPTA/CNT—COOH> PPTA/CNT—OH>PPTA/CNT—NH2 in the number and strength of hydrogen bonds. The relationship is reflected in the gain variation of thermodynamic properties of the composite system. The results show that the thermodynamic properties of the carboxylated carbon nanotubes aramid composite system are better than those of other functionalized doping systems, and the doping of functionalized carbon nanotubes does not change the dielectric constant of the composite system significantly, hence, it can still provide excellent insulation and protection properties.
[1] 谢庆, 蔡扬, 谢军, 等. 基于ALBERT的电力变压器运维知识图谱构建方法与应用研究[J]. 电工技术学报, 2023, 38(1): 95-106. Xie Qing, Cai Yang, Xie Jun, et al.Research on construction method and application of knowledge graph for power transformer operation and maintenance based on ALBERT[J]. Transactions of China Electrotechnical Society, 2023, 38(1): 95-106. [2] 刘道生, 周春华, 丁金, 等. 变压器纳米改性油纸复合绝缘研究综述[J]. 电工技术学报, 2023, 38(9): 2464-2479+2490. Liu Daosheng, Zhou Chunhua, Ding Jin, et al. Research overview of oil-paper composite insulation modified by nano particles for transformer[J]. Transactions of China Electrotechnical Society, 2023, 38(9): 2464-2479+2490. [3] 杜志叶, 肖湃, 郝兆扬, 等. 基于绕组热点温度反馈的特高压交流变压器低频加热干燥方法研究[J]. 电工技术学报, 2022, 37(15): 3888-3896. Du Zhiye, Xiao Pai, Hao Zhaoyang, et al.Study on low-frequency heating and drying method of UHVAC transformer based on temperature feedback of winding hot spots[J]. Transactions of China Electrotechnical Society, 2022, 37(15): 3888-3896. [4] 中国电力科学研究院. 国家电网公司变压器抗短路研究报告[R]. 北京: 中国电力科学研究院, 2006. [5] 廖瑞金, 刘骁, 刘捷丰, 等. 现场变压器油纸绝缘时频域介电特征量提取及状态评估[J]. 电力系统自动化, 2015, 39(5): 94-100. Liao Ruijin, Liu Xiao, Liu Jiefeng, et al.Extraction of time and frequency domain dielectric characteristics and condition assessment for field transformer oil-paper insulation[J]. Automation of Electric Power Systems, 2015, 39(5): 94-100. [6] 律方成, 路修权, 刘贵林, 等. 纳米Al2O3-STPP@HACC核壳填料的制备及其对间位芳纶绝缘纸性能的影响[J/OL]. 华北电力大学学报(自然科学版), 2022: 1-10. http://kns.cnki.net/kcms/detail/13.1212. TM. 20220801.1528.002.html. Lü Fangcheng, Lu Xiuquan, Liu Guilin, et al. Preparation of Nano-Al2O3-STPP@HACC core-shell filler and its effect on the properties of meta-aramid insulating paper[J/OL]. Journal of North China Electric Power University (Natural Science Edition), 2022: 1-10. http://kns.cnki.net/kcms/detail/13.1212.TM. 20220801. 1528.002.html. [7] Sun Baojie, Li Dongliang, Li Chenchen, et al.Preparation of silver nanoparticle functionalized aramid fiber by employing dopamine and silane coupling agent modification[J]. Journal of Applied Polymer Science, 2022, 139(47): e53190. [8] Yao Songjun, Chen Meijun, Huang Shiqi, et al.Mechanism of improvement in the strength of para-aramid paper by polyphenylene sulfide pulp[J]. Composites Communications, 2022, 34: 101250. [9] 谢璠, 陈珊珊, 梁栩, 等. PPTA@ZnO NWs的功能化修饰及导热绝缘纸基材料的制备与研究[J]. 中国造纸, 2019, 38(7): 1-7. Xie Fan, Chen Shanshan, Liang Xu, et al.Preparation of thermal conductive insulation paper based composite with functionalized PPTA@ZnO nanowires[J]. China Pulp & Paper, 2019, 38(7): 1-7. [10] 米彦, 葛欣, 刘露露, 等. 微秒脉冲电场强度对BNNSs取向程度和环氧树脂复合材料热导率的影响[J]. 电工技术学报, 2022, 37(6): 1533-1541. Mi Yan, Ge Xin, Liu Lulu, et al.Effect of microsecond pulsed electric field strength on the BNNSs orientation degree and the thermal conductivity of epoxy resin composites[J]. Transactions of China Electrotechnical Society, 2022, 37(6): 1533-1541. [11] Zhang Wenqing, Deng Xi, Sui Gang, et al.Improving interfacial and mechanical properties of carbon nanotube-sized carbon fiber/epoxy composites[J]. Carbon, 2019, 145: 629-639. [12] Zhang Qingjie, Wu Jianqiao, Gao Liang, et al.Dispersion stability of functionalized MWCNT in the epoxy-amine system and its effects on mechanical and interfacial properties of carbon fiber composites[J]. Materials & Design, 2016, 94: 392-402. [13] Kinloch A J, Mohammed R D, Taylor A C, et al.The effect of silica nano particles and rubber particles on the toughness of multiphase thermosetting epoxy polymers[J]. Journal of Materials Science, 2005, 40(18): 5083-5086. [14] 杜伯学, 孔晓晓, 肖萌, 等. 高导热聚合物基复合材料研究进展[J]. 电工技术学报, 2018, 33(14): 3149-3159. Du Boxue, Kong Xiaoxiao, Xiao Meng, et al.Advances in thermal performance of polymer-based composites[J]. Transactions of China Electrotechnical Society, 2018, 33(14): 3149-3159. [15] Fasanella N A, Sundararaghavan V.Atomistic modeling of thermal conductivity of epoxy nanotube composites[J]. JOM, 2016, 68(5): 1396-1410. [16] Chen Qidao, Dai Liming, Gao Mei, et al.Plasma activation of carbon nanotubes for chemical modification[J]. The Journal of Physical Chemistry B, 2001, 105(3): 618-622. [17] 韩智云, 邹亮, 辛喆, 等. 直流GIL绝缘子环氧树脂/碳纳米管复合涂层关键物理性能的分子动力学模拟[J]. 电工技术学报, 2018, 33(20): 4692-4703, 4721. Han Zhiyun, Zou Liang, Xin Zhe, et al.Molecular dynamics simulation of vital physical properties of epoxy/carbon nanotube composite coatings on DC GIL insulators[J]. Transactions of China Electrotechnical Society, 2018, 33(20): 4692-4703, 4721. [18] 丁咪, 邹亮, 张黎, 等. 功能化掺杂对交联环氧树脂/碳纳米管复合材料热力学性能影响的分子动力学模拟[J]. 电工技术学报, 2021, 36(23): 5046-5057. Ding Mi, Zou Liang, Zhang Li, et al.Molecular dynamics simulation of the influence of functionalized doping on thermodynamic properties of cross-linked epoxy/carbon nanotube composites[J]. Transactions of China Electrotechnical Society, 2021, 36(23): 5046-5057. [19] 晁楠楠. PPTA物理包覆羧基碳纳米管复合材料的制备及性能研究[D]. 烟台: 鲁东大学, 2018. Chao Nannan.Preparation and properties of PPTA coated carboxyl carbon nanotube composites[D]. Yantai: Ludong University, 2018. [20] 郭唐华, 陈圣岳, 彭懋. 氨基化二氧化硅包覆碳纳米管增强环氧树脂复合材料[J]. 材料科学与工程学报, 2014, 32(4): 475-479, 504. Guo Tanghua, Chen Shengyue, Peng Mao.Reinforcement of epoxy resin with aminated silica-encapsulated carbon nanotubes[J]. Journal of Materials Science and Engineering, 2014, 32(4): 475-479, 504. [21] 常艺, 裴久阳, 周苏生, 等. 功能化碳纳米管改性热塑性复合材料研究进展[J]. 材料导报, 2017, 31(19): 84-90. Chang Yi, Pei Jiuyang, Zhou Susheng, et al.Progress in functionalized carbon nanotubes-modified thermoplastic polymer nanocomposites[J]. Materials Review, 2017, 31(19): 84-90. [22] Leach A R.Molecular modelling: principles and applications[M]. 2nd ed. Harlow: Prentice Hall, 2001. [23] 杨小震. 分子模拟与高分子材料[M]. 北京: 科学出版社, 2002. [24] 朱孟兆, 陈玉峰, 辜超, 等. 基于分子动力学的无定形纤维素热力学性质仿真[J]. 高电压技术, 2015, 41(2): 432-439. Zhu Mengzhao, Chen Yufeng, Gu Chao, et al.Simulation on thermodynamic properties of amorphous cellulose based on molecular dynamics[J]. High Voltage Engineering, 2015, 41(2): 432-439. [25] Tang Chao, Zhang Song, Li Xu, et al.Molecular dynamics simulations of the effect of shape and size of SiO2 nanoparticle dopants on insulation paper cellulose[J]. AIP Advances, 2016, 6(12): 125106. [26] 李亚莎, 孟凡强, 章小彬, 等. 纳米SiO2掺杂对有水环境下间位芳纶绝缘纸性能影响的研究[J]. 原子与分子物理学报, 2020, 37(3): 371-377. Li Yasha, Meng Fanqiang, Zhang Xiaobin, et al.Study on theinfluence of nano-SiO2 doping on the performance of meta-aramid insulation paper in water environment[J]. Journal of Atomic and Molecular Physics, 2020, 37(3): 371-377. [27] Paavilainen S, Róg T, Vattulainen I.Analysis of twisting of cellulose nanofibrils in atomistic molecular dynamics simulations[J]. The Journal of Physical Chemistry B, 2011, 115(14): 3747-3755. [28] 廖瑞金, 胡舰, 杨丽君, 等. 变压器绝缘纸热老化降解微观机理的分子模拟研究[J]. 高电压技术, 2009, 35(7): 1565-1570. Liao Ruijin, Hu Jian, Yang Lijun, et al.Molecular simulation for thermal degradative micromechanism of power transformer insulation paper[J]. High Voltage Engineering, 2009, 35(7): 1565-1570. [29] 张华, 陈小华, 张振华, 等. 接枝羧基的有限长碳纳米管电子结构的第一性原理研究[J]. 物理学报, 2006, 55(6): 2986-2991. Zhang Hua, Chen Xiaohua, Zhang Zhenhua, et al.The first-principles calcultion of the electronic structure of finite length carbon nanotubes grafted by carboxyl[J]. Acta Physica Sinica, 2006, 55(6): 2986-2991. [30] 张华, 陈小华, 张振华, 等. 接枝羟基对有限长碳纳米管电子结构的影响[J]. 物理化学学报, 2006, 22(9): 1101-1105. Zhang Hua, Chen Xiaohua, Zhang Zhenhua, et al.Effect of grafted hydroxyl on the electronic structure of finite-length carbon nanotubes[J]. Acta Physico-Chimica Sinica, 2006, 22(9): 1101-1105. [31] Fan Zheyong, Hirvonen P, Pereira L F C, et al. Bimodal grain-size scaling of thermal transport in polycrystalline graphene from large-scale molecular dynamics simulations[J]. Nano Letters, 2017, 17(10): 5919-5924. [32] 季家友. 芳纶Ⅲ表面改性及其与环氧复合体系的结构与性能研究[D]. 武汉: 武汉理工大学, 2012. Ji Jiayou.Effects of modification on aramid fibers and properties and structures of aramid/epoxy resin composites performance[D]. Wuhan: Wuhan University of Technology, 2012. [33] Jund P, Jullien R.Molecular-dynamics calculation of the thermal conductivity of vitreous silica[J]. Physical Review B, 1999, 59(21): 13707-13711. [34] Müller-Plathe F.A simple nonequilibrium molecular dynamics method for calculating the thermal conductivity[J]. The Journal of Chemical Physics, 1997, 106(14): 6082-6085. [35] Kubo R.Statistical-mechanical theory of irreversible processes. I. General theory and simple applications to magnetic and conduction problems[J]. Journal of the Physical Society of Japan, 1957, 12(6): 570-586. [36] 何平笙. 高聚物的力学性能[M]. 2版. 合肥: 中国科学技术大学出版社, 2008. [37] 李璐. 矿用干式变压器Nomex绝缘多因子老化规律及寿命预测方法研究[D]. 太原: 太原理工大学, 2020. Li Lu.Research on multi-factor aging law and life prediction method of Nomex insulation for mining dry-type transformer[D]. Taiyuan: Taiyuan University of Technology, 2020. [38] 李亚莎, 孟凡强, 章小彬, 等. SiO2表面改性对间位芳纶绝缘纸性能的影响[J]. 绝缘材料, 2019, 52(7): 22-28. Li Yasha, Meng Fanqiang, Zhang Xiaobin, et al.Influence of surface modified SiO2 on properties of meta-aramid insulation paper[J]. Insulating Materials, 2019, 52(7): 22-28. [39] 孟凡强. 纳米SiO2掺杂及其表面改性对PMIA性能影响的研究[D]. 宜昌: 三峡大学, 2020. Meng Fanqiang.On the influence of SiO2 nano-doping and surface modification on the properties of PMIA[D]. Yichang: China Thrice Gorges University, 2020. [40] Fox T G, Flory P J.Second-order transition temperatures and related properties of polystyrene. I. influence of molecular weight[J]. Journal of Applied Physics, 1950, 21(6): 581-591. [41] Mazur P, Maradudin A A.Mean-square displacements of atoms in thin crystal films[J]. Physical Review B, 1981, 24(6): 2996-3007. [42] Tang Chao, Zhang Song, Li Xu, et al.Experimental analyses and molecular simulation of the thermal aging of transformer insulation paper[J]. IEEE Transactions on Dielectrics and Electrical Insulation, 2015, 22(6): 3608-3616. [43] 莫洋. 芳纶/天然纤维三层交联结构复合绝缘纸的研制[D]. 重庆: 重庆大学, 2021. Mo Yang.Development of aramid/natural fiber three-layer crosslinked composite insulating paper[D]. Chongqing: Chongqing University, 2021. [44] 杨保初, 刘晓波, 戴玉松. 高电压技术[M]. 4版. 重庆: 重庆大学出版社, 2018. [45] Kamata Y, Ohe E, Endoh K, et al.Development of low-permittivity pressboard and its evaluation for insulation of oil-immersed EHV power transformers[J]. IEEE Transactions on Electrical Insulation, 1991, 26(4): 819-825. [46] Prevost T A, Oommen T V.Cellulose insulation in oil-filled power transformers: part Ⅰ- history and development[J]. IEEE Electrical Insulation Magazine, 2006, 22(1): 28-35.
2024, Vol. 39 
