1. COMPARISON OF INFLUENCE OF PLASMA TREATMENT BY DSCBD AND INFRARED LASER RADIATION ON KEVLAR AND NOMEX FIBERS 
*Marie Štěpánková, Jakub Wiener
 Department of Textile Chemistry, Textile Faculty, Technical University of Liberec, Liberec, Czech Republic, Studentská 2, Liberec
* adress:
Plasma treatment has become an important industrial process for modifying polymer surfaces. By this method we can improve hydrophobicity or hydrophilicity of surface, chemical inertness, dyeability.
Infrared lasers are used in textile industrial applications for cutting and surface changing of textiles. With the aid of infrared lasers it is possible to improve biocompatibility or to provide medico-functionality for blood- and tissue-containing medical devices.
The aim of our work was quantification of surface changes of plasma treated and infrared laser irradiated Kevlar and Nomex nonwoven fabrics.
Introduction
Marked changes in surface structure of Kevlar and Nomex nonwovens were not observed after plasma treatment in the air or nitrogen (fig. bellow). There were not created ripple-like structure, which can be observed on conventional kinds of polymers like polyamides and polyesters.
Infrared laser affects on Kevlar and Nomex nonwoven by thermal effect as it can be seen from fig. 5 and 6.
Acknowledgement: This research has been supported by KAN
No significantly changes on plasma treated Kevlar and Nomex were observed by FTIR analysis and SEM analysis. The reason is that plasma can affect only surface layers of polymers.
Infrared laser has thermal effects on Kevlar and Nomex nowovens. During laser radiation Kevlar fibers are not melted. Laser causes only gradual heat decomposition of Kevlar nonwoven fabric. Nomex fibers are firstly melted. Subsequently it happens to their heat decomposition. a) b) c) d)
Plasma source of Diffuse Coplanar Surface Barrier Discharge (DCSBD) was used in different time for plasma treatment. Plasma treatment of Kevlar and Nomex nonwovens was performed in the air and nitrogen. For comparison untreated samples of nonwoven fabrics were analysed. Samples of nonwoven fabrics were irradiated by means of equipment Marcatec 150/250 Flexi, EasyLaser with wavelength 10,6 μm. Different experimental conditions concerning laser radiation were tested.
Experiment
Fiber surfaces and chemical compositions of Kevlar and Nomex nonwoven fabrics were determined by Fourier transform infrared spectroscopy (FTIR). No significant changes of surface structure of plasma treated Kevlar and Nomex nonwovens were observed.
It is possible to distinguish only heat decomposition of Kevlar and Nomex nonwoven fabrics by action of infrared laser radiation (fig. bellow). From IR spectra we obtained smoother curves with bow shape. Characteristic oscillations bonds of functional groups do not protrude from curve.
FTIR results
Surface structure
Fig. 2.: Irradiated Nomex nonwoven by infrared laser (duty cycle: 10%, pixel time: 300, 400, 500 μs)
Fig. 1.: Irradiated Kevlar nonwoven by infrared laser (duty cycle: 50%, pixel time: , 800 μs)
Fig. 3.: Kevlar fiber a) untreated, b) air plasma treated (5 min.), c) nitrogen plasma treated (5 min.)
Fig.4.: Nomex fiber a) untreated, b) air plasma treated (5 min.), c) nitrogen plasma treated (5 min.)
Fig. 5.: Kevlar nonwoven a) untreated, b) with lower intensity of laser, c) with medium intensity of laser, d) high intensity of laser
Fig. 6.: Nomex nonwoven a) untreated, b) with lower intensity of laser, c) with medium intensity of laser, d) high intensity of laser
Conclusions