Plasma Treatment of Crosslinked Polyethylene Tubes for Improved Adhesion of Water-based Paints

Cold plasmas fed trichloromethane-argon mixtures were used to treat cross-linked polyethylene (PE) to improve the adhesion of water-based paint. The effects of the plasma treatment undertaken at different percentages of CHCl3 in the plasma feed, CCl, were investigated using Infrared Spectroscopy in Diffuse Reflection (DR) mode, Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), X-ray Photoelectron Spectroscopy (XPS), goniometry for surface contact angle measurements, profilometry for roughness measurements, and paint adhesion tests. All the treatments modify the surfaces by introducing chlorine. Oxygen is present in the bulk and on the surfaces of the treated and untreated material. The treatments do not alter the bulk, but tend to increase the surface roughness and contact angle. When CHCl3 is present in the plasma subsequent paint adhesion is improved from a very poor classification of 4 to an excellent classification of 0 (assessed according to the appropriate Brazilian standards (BS EN ISO 2409:2007 and BS 3900-E6:2007A)). Surface roughness is not increased at low CCl but improved paint adhesion occurs for all CCl > 0. Although the causes of the improved paint adhesion with the plasma treatment are unclear, they may be related to the plasma activation of unsaturated carbon and oxygen functionalities.

采用冷等离子体（Cold plasma）馈入三氯甲烷-氩气混合气的方式处理交联聚乙烯（cross-linked polyethylene, PE），以提升其表面水性涂料的附着力。本研究针对等离子体进料中不同三氯甲烷（CHCl3）占比（记为CCl）下的等离子体处理效果，采用漫反射模式红外光谱（Infrared Spectroscopy in Diffuse Reflection, DR）、扫描电子显微镜（Scanning Electron Microscopy, SEM）、能量色散X射线光谱（Energy Dispersive X-ray Spectroscopy, EDS）、X射线光电子能谱（X-ray Photoelectron Spectroscopy, XPS）、接触角测角法、粗糙度轮廓仪法以及涂料附着力测试开展表征分析。所有等离子体处理均通过引入氯元素对材料表面进行改性。经处理与未处理试样的本体及表面均含有氧元素。等离子体处理不会改变材料本体结构，但会提升表面粗糙度与接触角。当等离子体进料中存在三氯甲烷时，涂料附着力可从极差的4级提升至优异的0级，评级依据BS EN ISO 2409:2007与BS 3900-E6:2007A标准。当CCl处于低水平时，表面粗糙度未出现提升，但所有CCl>0的工况下，涂料附着力均得到改善。尽管等离子体处理提升涂料附着力的具体机制尚不明确，但推测其可能与等离子体活化不饱和碳及含氧官能团有关。