Plasma treatment for multifunctional textiles PhD.eng.Visileanu EmiliaPhD.eng Ene AlexandraPhD.eng Mihai CarmenThe Research and Development Institut for Textile and LeatherBucharest - Romania

Finishing technologies Used to obtain products with high performancecharacteristics in order to increase :- proofing, hydrophilization, water repellency, fire retardancy, UV and bacteria resistance. Require the use of large amounts of:chemicals, water and energy.

Polluting industries

The effect on the environment makes the textile industry one of the most polluting industries !

Change structure and propertiesPhysical using different:energy sources such as plasma, laser, electromagnetic radiation, microwaves, etc.;

Chemical using different:chemicals that can change the surface or inner layers of the fibre; films: flame retardant, electrostatic charge protection , microorganism protective ;- metal deposition.

Plasma treatmentPlasma treatment is an innovative alternativesolution for the change of functional properties oftextiles; Material surface is modified microscopically by :- environmentally-friendly and - cost effective dry coating;This operation is possible without :- auxiliary mechanical processes or- chemicals .

Plasma The term plasma, was used for the first time by Irving Langmuir

Relation with biological environment;

It refers to electrically conductive ionized gas.

Plasma state of a gas - also considered as the fourth state of matter

Plasma enviromentPlasma environments are electrically quasineutral physical systems consistingof: electrons, ions, photons of ultraviolet radiation, free radicals, neutral moleculesObtained by: the action of high temperatures,

strong magnetic fields or electric discharge in gases.

Direct or alternative current can be used .

Cold plasmaCold plasma- low temperature (below 150oC) is used for :- the treatment of textile materials and fibres without :thermal degradation;

Low pressure cold plasma treatment technology - vacuum plasma technology ; Low pressure plasma technology has some advantages over the atmospheric pressure plasma :- controllable and - reproductible.

These environments have low, medium or total ionization.

Plasma principle

The principle of plasma treatment consists of :- putting into contact the textile material with this very reactive environment. Installations apply treatments on :- fibres, semi-finished products (sliver, roving), yarns or flat surfaces (woven, knitted fabrics, nonwoven textiles).

The following treatment can be produced at the surface of textile materials:superficial changes in the surface (cracks, roughness, micro-craters);obtaining radicals for the fibre grafting.Plasma environments can be also obtained

Fibre grafting

Action of the reactive groups :

Caracteristics The elements of the coating have to be:- firmly attached to the surface andthe layer has to have a definite degree offreedom .

This ultrathin grafted is :-first monolayer of coating, which is in contact with the surface and :-will be a guide for further coating treatmet organization.

Posible effectsPlasma treatments may result in changes in :the surface morphology (with effects on roughness), mass per unit area of surface and mass per unit length,some physical-mechanical properties (length density, break load, break elongation, etc), self-adherence, absorption properties andimproved comfort properties as well as improved electrical properties.

Potential applications of plasma treatment can be used in: - conventional textile products as well as in technical articles (grafting of hydrophilic polymers) and composites, waterproof articles (grafting of fluorinated polymers), fireproof articles (e.g. polyphosphonate grafting) , high conductivity articles (grafting of organic metal-containing molecules), antimicrobial, UV protection and so on .

Installation CD 400 Roll-to-roll The loading system is formed of:sets of trays for the treatment of fibres, semi-finished products (slivers, rovings), yarns;a complete roll winding system for flat materials: woven , knitted, nonwoven fabrics or foils. Components: Air tight chamber (plasma environment); High frequency power generator;Vacuum pumps;Gas cylinders;Electrodes;Sample holders, etc.

ActionsIn the airtight chamber vacuum is generated by vacuum pumps operating at a pressure in the range 10-2 to 10-3 mbar. Gas taken from the cylinder is:placed in the chamber and is ionized by a high frequency generator.

FeaturesA specific feature of the plasma is thevisible luminescent discharge ;The colours ranging are:- from blue-white to dark purple and are:depending on the type of gas used in theplasma installation;Highly reactive particles react with the textile material surface.

Industrial instalationFor vacuum plasma treatment of fabrics with the width of more than 0.6 m, :special vacuum chambers with :winding rollers with :a diameter greater than 0.3 m.Such chambers have normally three sections: - a wind, a rewind and

a plasma treatment section which are differentially supplied with plasma.

Tension control All special plasma treatment installations type "Roll-to-roll" use tension control of the textile material.

Table no.1 presents the gases used in the installation and the plasma effects on the textile surfaces.

Interaction with surfaces (table 3) The following notations are used: -e electron, -(s) location of an open surface, -A(s) a surface-related particle category, -B(b) a category of particles B in the whole mass and -Am is a metastable state with long lifetime

Table no. 4 Elements of comparison between classical finishing treatments of textile materials and treatments in plasma environment

Free surface energyPlasma treatments induce :changes (increases) of free surface energy of the polymers ; this resist - 200 hours since the application of the plasma treatment and :- lead to higher values compared with the untreated samples.

Wool knitted fabricResearch work used a wool knitted fabric, without special pretreatment.

Plasma treatment was performed in a plasma chamber of 1m3, using O2 plasma generated by a plasma generator with frequency of 40kHz, a power of 2000 to 3500 watt. Treatment times varied from 1 to 7 minutes.

EffectsThe most important effects observed during theresearch were: improved absorption of liquid by a factor of 100 to 1000; no significant change was observed in the mechanical properties of individual fibers; change in the mechanical properties of the yarns: - an increase yarn tenacity up to 50%; - an increase in the elongation at break of the yarn up to 250%; increase of the surface hydrophilicity by high capillarity.

Antifelting property and resistance to shrinkage during washing. - antifelting property and resistance to shrinkage during washing.Initial contraction of the fabric surface of 57% can be reduced tobelow 10% after plasma treatment, giving the treated material asuper-wash property.- antifelting treatment is less destructiv than the treatmentwith chemical reagents.Plasma antifelting treatment Antifelting treatment with chemical reagents

Healthcare application Polyester

Types of rawmaterials Cotton

The process for obtaining the anti-microbial products diagram:

ANTI- MICROBIAL TESTS

ANTI- MICROBIAL TESTS

Other advantages Lower energy consumption; Ease of adapting the process to industrial use; Reduction of water use (dry treatment processes remove rinse-spin-drying); Elimination of toxic substances.