Short-time plasma surface modification of HDPE powder in a Plasma Downer Reactor - process, wettability improvement and ageing effects
Short-time plasma surface modification of HDPE powder in a Plasma Downer Reactor - process, wettability improvement and ageing effects
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DOI：
10.1016/j.apsusc.2005.02.099
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发表时间：
2005-12-15
影响因子：
6.7
通讯作者：
von Rohr, PR
中科院分区：
文献类型：
--
作者：
Arpagaus, C;Rossi, A;von Rohr, PR
研究了在等离子体下行反应器中，用等离子体表面改性技术在0.1 s内改善HDPE粉体润湿性的效果。揭示了XPS结果（O/C比）和润湿性（接触角，极性表面张力，毛细管上升法）之间的相关性。等离子体进料气体中的O-2-含量已被调整以获得最佳润湿性。XPS结果表明，在粉体表面形成了C=O和COOH官能团。对于等离子体处理的HDPE粉末表面，0/C比从0.0（在未处理的粉末上没有氧）增加到0.15。使用纯O-2-等离子体处理，实现了水接触角从> 90度（没有水渗透到未处理的PE粉末中）降低到65度。总表面自由能从31.2 mN/m增加到45 mN/m。经处理的粉末的老化发生并且主要在储存的前7天内进行。接触角测量和O 1 s/O2 s强度比数据支持老化主要是扩散控制的过程。尽管如此，XPS结果显示甚至在40天后仍存在氧官能团，这解释了为什么该粉末在不添加任何表面活性剂的情况下仍然可分散在水中。(c)2005 Elsevier B. V.保留所有权利。
The effectiveness of improving the wettability of HDPE powders within less than 0.1 s by plasma surface modification in a Plasma Downer Reactor is investigated. A correlation is revealed between the XPS results (O/C-ratio) and the wettability (contact angle, polar surface tension by capillary rise method). The O-2-content in the plasma feed gas has been adjusted for best wettability properties. XPS results indicate the formation of C=O and COOH functional groups on the powder surface. The O/C-ratio increased from 0.0 (no oxygen on the non-treated powder) up to 0.15 for the plasma treated HDPE powder surface. With pure O-2-plasma treatment, a water contact angle reduction from > 90 degrees (no water penetration into the untreated PE powder) down to 65 degrees was achieved. The total surface free energy increased from 31.2 to 45 mN/m. Ageing of treated powders occurs and proceeds mostly within the first 7 days of storage. Contact angle measurements and O1s/O2s intensity ratio data support that ageing is mainly a diffusion-controlled process. Nevertheless, XPS results show the presence of oxygen functional groups even after 40 days, which explains why the powder is still dispersible in water without any addition of surfactants. (c) 2005 Elsevier B.V. All rights reserved.