Penetration of plasma effects into textile structures

doi:10.1016/S0257-8972(01)01055-6

Surface and Coatings Technology

Volumes 142–144, July 2001, Pages 489-493

https://doi.org/10.1016/S0257-8972(01)01055-6 Get rights and content

Abstract

The penetration of plasma into textile materials turns out to be a crucial point for plasma modification of fabrics. Throughout the process where plasma treatment can be applied approximately 1–100 mbar is evaluated to be the optimum. This is due to the correlation between characteristic geometrical distances in fabrics and the mean free path of modifying particles in the gas phase as well as the energy transfer from activated plasma particles to surrounding inactive gas particles and to surface sites of textile fibres. Theoretical calculations and experimental results for the hydrophilisation of fabrics prove this behaviour.

Introduction

The pretreatment and finishing of textile fabrics by plasma technologies is increasingly replacing wet chemical applications. Plasma treatment modifies the uppermost atomic layers of a material surface and leaves the bulk characteristics unaffected. The possible aims of this are the affection of wettability, adhesion, or reflectivity, etc. (e.g. [1], [2], [3], [4], [5], [6], [7], [8], [9], [10]).

In fabrics there is a difference between the visible surface and actual inner surface to be modified in contrast to foils or plates. A fabric consists of a complex structure of single fibres and threads that are distributed over the fabric thickness. The entire thickness of fabrics may range up to several millimetres. To ensure the plasma has an effect on the surface of all single fibres within the entire fabric the modifying particles must move through the textile structure in an acceptable time, keeping their modifying ability.

This paper investigates this non-trivial problem in the case of hydrophilisation of cotton fabrics in an oxygen plasma taking the gas pressure as the most important process parameter.

Section snippets

Theoretical background

Plasmachemical conversion of the feed gas produces chemically active particles (e.g. O radicals) that are able to modify textile surface molecules via chemical reactions after impinging on the surface. The radicals generated inside the plasma region must be given the opportunity to move to the reaction place at the textile fibre surface. Thereby the path of radicals between the locations of generation and reaction is limited on the one hand by the distance between single fibres, and on the

Low pressure

The plasma treatment experiments at low and medium pressure were carried out at a woven cotton fabric (115 g/m²) to hydrophilise the textile material. For the study of the penetration depth of the plasma effect several fabric layers were put together tightly in order to simulate a total fabric thickness of approximately 1 mm. The hydrophilisation effect was measured by a suction test. A capillary is filled with a test liquid (coloured water) and positioned onto the according surface of the

Conclusions

Plasma modification of voluminous fabrics over the entire thickness has its own specifics. Due to fabric structure and collision characteristics the pressure turns out to be a crucial process parameter for optimal treatment. The applied pressure value must be matched to the characteristic structure of the textile material to be plasma treated. The pressure range from approximately 1 to 100 mbar is applicable to most of the existing textile structures and leads to an optimal plasma effect

Acknowledgements

The project was supported by BMBF, FKZ 13N6893.

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Penetration of plasma effects into textile structures

Abstract

Introduction

Section snippets

Theoretical background

Low pressure

Conclusions

Acknowledgements

Compos. Sci. Technol.

Melliand

Techn. Textilien

Text. Res. J.

Text. Praxis Int.

Text. Res. J.