Plasma Modification Of Polyester Fabrics For Improved Functionality

Over the past decade,there has been a growing interest in plasma treatments of fabrics to improve their surface properties like wettability and adhesion to other materials（metals,resin,etc）.Compared to conventional wetchemical textile finishing,plasma technology has also a bright future because of its environmental sustainability.Polyester fabrics reveal a moderate hydrophilic character due to the lack of polar groups at their surfaces.To obtain a good wettability,i.e.a high surface energy,some polar groups should be formed at the fabric surface.In addition, super hydrophobicity is also required in some technical applications.But the plasma modified effect of the fabric is influenced by many factors,e.g.the feed gas,the textile structure and chemistry,the treatment time,the process pressure and the power.Therefore,we applied a low pressure and low temperature plasma treatment with different gases to obtain a hydrophilic surface of polyester fabrics and varied pressure and treatment time to try to get an optimized result.After that,we investigated its hydrophilization effects with the aging,i.e.as a function of storage time in air after the treatment.The best effects are obtained at different pressures due to the different fabric structures,and the lowest aging effects are not always obtained at the same pressures as the best hydrophilization effects（as obtained right after the treatment）. It seems that there is no direct correlation between the optimal pressure for obtaining fast treatment effects and the optimal pressure for obtaining sta- ble effects（limited aging）.For a certain fabric,the treatment effect,i.e.the sink time immediately after the treatment,is mostly influenced by the number of polar groups formed on the fibers exposed on fabric surface.But the aging is mostly influenced by the stability of polar groups and the activation degree of the whole fabric.A higher pressure may produce a plasma region on the fabric surface with higher radical concentration,but this will limit the radicals to penetrate into the inner-fabric.And higher pressure can also weaken the stability of polar groups by over-treatment.That’s why in our experiments a good aging result was always obtained at a lower pressure.Moreover,we introduced also a different approach based on nanoporous plasma coatings with NH₃:C₂H₄,called "plasma polymerization".This process may form a thin film that mainly contains amine groups,and the film is used as a template for the anchoring of hydrophilic or hydrophobic functional molecules from the next process,"chemical derivatization".Compared to the normal plasma treatment,the results of "plasma thin film deposition with chemical derivatization" are much more stable.For Multil,the optimal results of the two methods were in the same level,so for some loose structure fabric,plasma treatment can already satisfy the normal use,and it’s also simpler and more convenient.However,the wash-fastness of plasmatreated fabrics still has to be investigated.For Multi2,it’s obvious that plasma thin film deposition with chemical derivatization obtained a much better result. For some tight fabric,plasma thin film deposition with chemical derivatization is more effective compared with the normal plasma treatment.For monofilament fabric,we can’t expect it absorb water like multifilament fabric because of lack of capillary,but the surface adhesion can be modified to a certain extent by plasma treatment. Plasma thin film deposition with chemical derivatization can also get a very good hydrophobization effect to polyester fabric.It can be applied for some hydrophobization function in textile such as self-cleaning.Though the result of plasma thin film deposition with chemical derivatization appears more stable,it has still its disadvantages.Firstly,in our experiments, some powder was left on the fabric surface after some of the chemical derivatization methods and was hard to be completely removed.Secondly,it is more complex and needs longer time than plasma treatment.Therefore,maybe with some improvement,such as elimination of chemical derivatization powder,we can expect this plasma treatment method to be spread more widely.