Enhancement and Mechanism of NH<sub>3</sub> Plasma Treatment on Interfacial Combination of PMTA and Cellulose Insulation Matrix
Wei Hou, Lijun Yang, Yong Feng, Fei Yin, Yuxin He, Jiajun Li
Abstract
Interfacial bonding is significant in determining the mechanical properties and dielectric loss of polymer composites. In this study, NH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> plasma treatment is used to reinforce the interfacial bonding between polyisophthaloyl metaphenylene diamine (PMTA) and the cellulose matrix. The mechanism of modification is investigated via x-ray photoelectron spectroscopy (XPS) and density functional theory (DFT). Additionally, molecular dynamics (MD) simulations are performed to explore the microscopic mechanism of the performance improvement of the composite insulation paper. The experimental results show that the mechanical property is improved and dielectric loss decreased to a certain extent after treatment. According to the results of XPS and DFT, the treatment introduces a polar group, −NH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> , into the C18 position of PMTA. PMTA treated with NH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> plasma (T-PMTA) is conducive to form H-bonds with cellulose. It increases the interaction energy and strengthens the interfacial bonding, causing the T-PMTA molecules to penetrate wider and deeper on the cellulose surface. Thus, the mechanical properties are improved. Additionally, the improved interfacial bonding impedes the rotation and movement of molecules at the interface, which reduces the degree of freedom of the dipole steering and the resulting low dielectric loss. This study reveals the mechanism of NH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> plasma treatment and provides insights into the microscopic mechanism of the improvement of properties of composite insulation paper at the molecular level.