Plasma-Technology-in-Textiles (1).pptx

A gas is normally an electric insulator. However, when a
sufficiently large voltage is applied across a gap containing a gas or
gas mixture, it will breakdown and conduct electricity.
The reason is that the electrically neutral atoms or molecules of the
gas have been ionised, i.e. split into negatively charged electrons
and positively charged ions.
The nature of the breakdown and the voltage at which this occurs
varies with the gas species, gas pressure, gas flow rate, the
materials and the nature, geometry and separation of the surfaces
across which the voltage is sustained.
The resulting ionised gas is often called a discharge or plasma
INTRODUCTION

WHAT IS A PLASMA ?
 States of Matter
 Solid, Liquid, Gas, Plasma
 And plasma technology is based on the concept of the
electrons and their movement in the electric field.

WHAT PLASMA CONSISTS OF?
 The coupling of electromagnetic power into a process gas volume generates the
plasma medium comprising a dynamic mix of ions, electrons, neutrons,
photons, free radicals, meta-stable excited species and molecular and polymeric
fragments, the system overall being at room temperature. This allows the
surface functionalisation of fibers and textiles without affecting their bulk
properties.
 Definition
 A commonly accepted deﬁnition of plasma is: a partially ionized gas composed
of highly excited ionic and radical species, as well as photons and electrons

 A plasma is defined as a collection of positive
and negative charges which act collectively.
 A major consequence of this collective
behaviour is the ability of the plasma to screen
out local density perturbations and to create a
sheath region between the plasma and contact
surfaces.
DEFINITION OF PLASMA

PRINCIPLE OF PLASMA PROCESSING
Plasma technology is a surface-sensitive method that allows selective modification
in the nm-range. By introducing energy into a gas, quasi-neutral plasma can be
generated consisting of neutral particles, electrically charged particles and
highly reactive radicals. If a textile to be functionalized is placed in a reaction
chamber with any gas and the plasma is then ignited, the generated particles
interact with the surface of the textile. In this way the surface is specifically
structured, chemically functionalized or even coated with nm-thin film
depending on the type of gas.

PLASMA PARAMETERS:
 Primary parameters:
 Gas type
 Residence time
 Secondary parameters:
• Gas flow
• Frequency
• Power
• Pressure
• Low pressure: 5.10-2 - 1 mbar
 Ambient temperature: 30 - 40 °C
 Gasses: O2,N2,Ar,He,CxFy,H2,CH4,…
 Liquid monomers: HMDSO,…
 Frequency’s: KHz, MHz, GHz

HOW DEPTH IT ACTS?
 All these phenomena are limited to the most external layer of the
substrate.
 Normally, the effects do not involve layers deeper than 10–100 nm.
 However, it must be noticed also that ultraviolet (UV) or vacuum
ultraviolet (VUV) radiation (with wavelength <200 nm) is an important
component of plasma because it can give rise to a variety of
photochemical interactions with the substrate.

GENERIC SURFACE ENGG. PROCESS
 Four types of surface engg. Process:-
 Etching/Cleaning
 Activation
 Grafting
 Polymerization

Etching/Cleaning
For such a phenomenon to occur, ‘inert’ gases (Ar, He, etc.),
nitrogen or oxygen plasmas are typically used. The
bombardment of the substrate with the plasma species
causes the breakdown of covalent bonds. As a consequence,
detachment of low molecular weight species (ablation) takes
place. In this way, contaminants or even thin layers of the
substrate are removed, producing extremely ‘clean’ surfaces,

Activation
Interaction with plasma may induce the formation of active sites on the textile
surface (radicals or other active groups, such as hydroxyl, carboxyl, carbonyl,
amine groups), which can give rise to chemical reactions, not typical of the
untreated material, with substance brought in contact with the material after
plasma processing.

GENERIC SURFACE ENGG.
PROCESS
Grafting
 Radical species present in the plasma may be directly grafted onto the
polymer surface

Polymerization
By using specific molecules, a process known as plasma-enhanced chemical
vapor deposition (PECVD) may occur. These molecules, activated in the
plasma, may react with themselves forming a polymer directly on the surface of
the substrate. Depending on the different experimental conditions, chemically
unique, nanometric polymeric coatings are obtained and chemical, permeation,
adhesion and other properties of the starting material can be dramatically
modified.

EFFECT OF PLASMA ON ﬁBRES AND
POLYMERS
 Textile materials subjected to plasma treatments undergo major chemical and
physical transformations including
 chemical changes in surface layers,
 changes in surface layer structure, and
 changes in physical properties of surface layers.
 Plasma treatment on ﬁber and polymer surfaces results in the formation of
new functional groups such as —OH, —C=O, —COOH which affect fabric
wet ability as well as facilitate graft polymerization which, in turn, affect
liquid repellence of treated textiles and nonwovens.

CLASSIFICATION OF PLASMA
On the basis of pressure in plasma chamber- Atmospheric
Pressure and low pressure plasma.
On the basis of degree of ionization and the temperature of
electrons and ions-Hot and cold plasma.
On the basis of frequency of the power supply DC and AC
plasma(RF, Microwave, GHz Plasma).
Depending upon the electron affinity of the process gases
used-Electropositive and electronegative gas plasma.
Any plasma reactor will be a combination of all of the above, e.g. one
atmosphere glow discharge cold plasma is based on cold, AC and atmospheric
pressure plasma.

Low pressure
(Vacuum)
Atmospheric
pressure
Technological
Plasmas

Glow Discharge
Corona discharge
Atmospheric pressure plasmas
Atmospheric pressure plasma jet
Dielectric Barrier Discharge

CORONA DISCHARGE
 It is formed at atmospheric pressure by applying a low frequency or
pulsed high voltage over an electrode pair,
 Corona discharge usually involves two asymmetric electrodes; one
highly curved and one of low curvature The high curvature ensures a
high potential gradient around one electrode, for the generation of a
plasma.
 An important reason for considering coronas is the production of
ozone around conductors undergoing corona processes
 Plasma density drops off rapidly with increasing distance from the electrode.

DIELECTRIC BARRIER DISCHARGE
 This is also an atmospheric-pressure plasma source. In this we uses a
dielectric covering over one or both the electrodes, of which one is
typically low-frequency driven, while the other is grounded.
 The purpose of dielectric film is to restrict and rapidly terminate the
arcs that form in the potential field between the two electrodes.
 It is used in production for large area flat television screens
 a major advantage over corona discharges is the improved textile
treatment uniformity.

GLOW DISCHARGE PLASMA
 It is the oldest type of plasma technique. It is provides the highest
possible uniformity and flexibility of any plasma treatment. The
plasma is formed by applying a DC, low frequency (50 Hz) or radio
frequency (40 kHz, 13.56 MHz) voltage over a pair or a series of
electrodes. (Figure A, B, C)

ATMOSPHERIC PRESSURE PLASMA JET (APPJ)
 Atmospheric Pressure Plasma Jet is the most promising technique among all
Atmospheric Pressure Plasma Techniques and is widely used for textile processing.
 APPJ produce a stable, homogenous and uniform discharge at atmospheric pressure
using 13.56 MHz
 Atmospheric-pressure plasmas have prominent technical significance because in
contrast with low-pressure plasma or high-pressure plasma no reaction vessel is
needed to ensure the maintenance of a pressure level differing from atmospheric
pressure. Accordingly, depending on the principle of generation, these plasmas can
be employed directly in the production line.

Advantages and Disadvantages of APP
 The advantages of atmospheric pressure plasma are:
 continuous treatment can be given, and
 it is cost effective process.
 On the other hand, the disadvantages of atmospheric pressure plasma are:
 difficulty of sustaining of glow discharge,
 higher voltages are required for gas breakdown, and
 difficult to form uniform plasma through out the reactor volume.

Low pressure (Vacuum) Plasmas
Low pressure plasma has found wide applications in materials
processing and play a key role in manufacturing semiconductor devices
The temperature of the gas is usually below 1500C, so that the
thermally sensitive substrates are not damaged
Vacuum vessel is pumped down to a pressure in the range of
10-3 to 10 mbar with the use of high vacuum pumps. The
gas which is then introduced in the vessel is ionised with
the help of a high frequency generator. The advantage of
the low-pressure plasma method is that it is a well
controlled and reproducible technique.

ADVANTAGES & DISADVANTAGES OF LOW
PRESSURE PLASMA
 Advantages:
(i) the generate high concentrations of reactive specie that can etch and deposit
thin films.
(ii) uniform glows is obtained.
(iii) the temperature of the gas is usually below 1500C, so that the thermally
sensitive substrates are not damaged.
(iv) low breakdown voltages.
 Disadvantages:
(i) vacuum systems are expensive and have high maintenance cost.
(ii) Size -of the object to be treated is limited by the size of the vacuum
chamber.

HOT PLASMA
THERMAL PLASMA
COLD PLASMA
CATEGORIES OF PLASMA’S

VACUUM & ATMOSPHERIC PLASMA
Vacuum
 Easy to create
 Large volume
 Batch process
 Capital intensive
 High running cost
Atmospheric
 Difficult to create
 Smaller volume
 Continuous process
 Low cost
 Low running cost
Technologically Preferable

WHY PLASMA TREATMENT OF TEXTILES ?
 It is a surface treatment
 Does not affect the bulk properties
 Versatile and uniform treatment
 Environmental friendly process

WHAT GAS PLASMA, DOES WHAT?
 Helium/oxygen plasma treatment of PP introduces oxidized functional groups onto the
surface, which may include alcohol, ketone, carboxy, ether, ester or hydroperoxide. The
introduction of polar groups onto the PP fibres allows chemical bonding with, for
example, dye molecules, in contrast to the untreated PP molecular chains which are non-
polar giving a hydrophobic surface.
 Oxygen and oxygen-containing plasmas impart functional groups such as C-O, C=O, O-
C=O and C—O—O, as well as surface etching of fibres, all enhancing wettability and
adhesion characteristics.
 Fluorine and fluorine containing gases (CF4, C2F6) result in the incorporation of fluorine
into the surface, resulting in hydrophobicity.
 Nitrogen and ammonia plasmas introduce amino (—NH2) and other nitrogen containing
functionalities onto natural and synthetic fibres. On wool, these are dye sites increasing
dye absorption.
 Treatment of PTFE with hydrogen-containing plasmas such as forming gas
(N2/H2::95%/5%) and ammonia results in large increase in surface energy due to a high
defluorination rate resulting in the formation of C—C, C—H and C=C bonds and cross-
links, and to nitrogen and oxygen species grafted onto the treated surface

DISADVANTAGES
Expensive
Slow
Plasma Surface Engineering

PLASMA TREATMENT VS. TRADITIONAL
TEXTILE PROCESSING

APPLICATION OF PLASMA
TECHNOLGY IN TEXTILE

-
POTENTIAL USE OF PLASMA TREATMENTS
 desizing of cotton fabrics.
 Hydrophobic enhancement of water and oil-repellent textiles
 Anti-felting/shrink-resistance of woollen fabrics.
 Hydrophilic enhancement for improving wetting and dyeing.
 Hydrophilic enhancement for improving adhesive bonding
 Removing the surface hairiness in yarn.
 Scouring of cotton, viscose, polyester and nylon fabrics.
 Anti-bacterial fabrics by deposition of silver particles in the
presence of plasma.
 Room-temperature sterilization of medical textiles.

DESIZING
Plasma technology can be used to remove PVA sizing material
from cotton fibers.
In conventional desizing process we use chemicals and hot
water to remove size.
 But desizing with plasma technology we can use either
O2/He plasma or Air/He plasma.
Firstly the treatment breaks down the chains of PVA making
them smaller and more soluble. X-ray photoelectron
microscopy results reveal that plasma treatment introduces
oxygen and nitrogen groups on the surface of PVA which
owing to greater polarity increase the solubility of PVA.
Of the two gas mixtures that were studied, the results also
indicate that O2/He plasma has a greater effect on PVA
surface chemical changes than Air/He plasma.

WATER REPELLENT FINISHING ON COTTON
The literature on water-repellency and waterproofing is frequently
confusing, because the repellency effect observed depends upon the test
method and the test conditions used.
The term ‘water-repellent’ is actually a relative term because there is
always some attraction between a liquid and a solid with which the liquid
is in contact.
The term ‘waterproof’ is normally taken to represent the conditions
where a textile material (treated or untreated) can prevent the absorption
of water and also the penetration of water into its structure.

DIFFERENCE B/W HYDROPHOBIC/PHILLIC
SUBSTRATE

WATER REPELLENCY ON COTTON BY PLASMA
TREATMENT
To get water repellent effect on the substrate we can use
flurocarbon gas, siloxanes and CH4 gas.
The textile substrate which we have to be functionlized is placed in
plasma chamber and then plasma is ignited on to the substrate and
then these molecules react with themselves forming a polymer layer
directly on the substrate as shown in the fig.
This process produce a substrate having very low surface tension
and thus the surface behaves like a water and oil repellent fabric.
PLASMA
CH4/Ar
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c

WORKING
 Hydrophobic coating layers were produced by plasma polymerization of CH4. The substrate
was continuously translated under the plasma deposition region at a speed of 5–10 cm min2
.The usable plasma area is 1 cm wide and 16 cm long. Helium or argon was used as a carrier
gas (5–10 l min21) and CH4 was used as a reactive gas (10–40 sccm). The power was
controlled in the range of 250–400 W. Samples were mounted on a computer-controlled
moving stage that traveled about 0.3–0.5 cm below the plasma source along the orthogonal
direction to the plasma source head. In typical processes, the substrate was repeatedly passed
back and forth across the glow-discharge plasma region at a speed of 5–10 cm min21.
 Here we can either use hexamethyldisiloxane gas,Fluorine and ﬂuorine containing gases (CF4,
C2F6) ETC.

FELTING OF WOOL
The process of felting involves relative movement of the fibers which may be
caused either by mechanical rubbing or by a series of compression-extension
operation.
Under the influence of these intermittent forces of squeezing, twisting etc.,
the wet fibers migrate in a preferential root ward direction because of the DFE,
and at the same time they tend to curve, loop and entangle with each other. This
is the reason of Felting of Wool.
This process is irreversible. Because of the anchoring effects of the
entangling and the differential frictional properties of fibres.
Crimpiness, flexibility and hygroscopic quality combined with delicacy of
fibers, are the most important factors in felting.
Felting is a complex process, and the felting capacity depends not only on the
inherent properties of wool, but also on the conditions of the felting process.

ANTI FELTING TREATMENT ON WOOL BY
PLASMA TECHNOLOGY
Plasma treatment of wool fibers has shown to reduce this curling effect by etching off the
exocuticle that contains the disulfide linkages which increase cross linking and
contribute towards shrinkage. This procedure also enhances wetability by etching off the
hydrophobic epicuticle and introducing surface polar groups.The increase in surface area
of the fiber, recorded with atomic force microscopy, is increased from 0.1m2/g to
0.35m2/g. These physio chemical changes degrease the felting/shrinkage behavior of
wool from more than 0.2g/cm3 to less than 0.1g/cm3.
For this process we may use oxygen, nitrogen or mix. Of these gases.

DYEING
 Dyeing and printing. Several studies have shown that dye ability or printability of
textiles can be markedly improved by plasma treatments. This effect can be
obtained on both synthetic and natural fibres. Capillarity improvement,
enhancement of surface area, reduction of external crystallinity, creation of
reactive sites on the fibres and many other actions can contribute to the final effect
depending on the operative conditions. Also production of colors on fibres
exploiting diffraction effects has been attempted.
 E.g.. The dye exhaustion rate of plasma treated wool has been shown to increase
by nearly 50%. It has been shown that O2 plasma treatment increases the
wetability of wool fabric thus leading to a dramatic increase in its wicking
properties. Also the disulphide linkages in the exocuticle layer oxidize to form
sulphonate groups (which is act as active sites for reactive dyes)which also add to
the wetability . The etching of the hydrophobic epicuticle and increase in surface
area also contributes towards the improvement in the ability of the fibers to wet
more easily

 The graph below [19] shows that plasma treated wool can achieve 90%
exhaustion in 30 minutes as compared to 60 minutes for untreated samples.
 when wool is dyed with reactive dyes maximum exhaustion is achieved A
possible explanation to this behavior of reactive dyes is due to the increase
in sulphonate groups on the fiber surfaces.

USES OF PLASMA TECHNOLOGY IN DIFFERENT
FIELDS:-
The plasma technology is widely used in the
 electronic industry,
 textiles,
 manufacturing,
 medical researches and technology,
 optical technology
 and many such fields which require quality production ,which are sustainable
and environment friendly as well.

ENVIRONMENT ASPECTS
 plasma technology holds tremendous potential to develop processes which can limit the
environmental impact of textile processing and contribute towards sustainable
development. Savings with plasma treatment can be due to a variety of factors but
mostly relate to conservation of water and energy as plasma treatment leads to dramatic
reductions in the use of both.
 Such as in making textile hydrophilic surfaces of fibers to hydrophobic Conventionally
these treatments are performed by pad/dry/cure treatments which utilize large amounts
of water and also require heat to cure the applied chemical
 In contrast plasma treatment can achieve the same effect by applying a gas such as
oxygen for etching and a flourocarbon in gaseous state for nanolayering by using
comparatively very little electrical power and also performing the same action in much
lesser time.

CONTINUE…..
 Anti felt treatment of wool which normally requires the application of harmful
chlorine based chemical on the surface of the fibers to degrade the epicuticle
and exocuticle to increase the hydrophilicity of the fibers and remove their
directional scales can be done using a plasma gas treatment such as O2. This
leads to the elimination of the wet treatment and also avoids the use of
environmentally non friendly chlorine based chemicals
 Desizing of plasma treated fabics has shown that by introducing polar groups on
the surface of cotton with O2 plasma the fabric can be desized in water at room
temperature rather than the 90o C bath conventionally required. This can lead to
energy savings because heating of the bath will not be required Also the
introduction of polar groups effectively reduces the time required for scouring
by about 45% from 40 to 25 minutes to achieve similar results
 Plasma treated fibers also show quicker and higher exhaustion of dyestuff
leading to less processing times and lesser amounts of chemical in waste water,
thus leading to more efficient use of energy resources and less hazardous waste
in discharged water

DRAWBACK OF PLASMA TECHNOLOGY
Plasma treatment, however, does have certain draw backs. The
treatment tends to produce harmful gasses such as ozone and nitrogen
oxides during operation . This happens due to the formation of free
radicals and nascent oxygen during the treatment, which react with
atmospheric gasses to form harmful bi products. In some cases,
contaminations from the substrate such as sulphur from the cystine
links in wool can react with atmospheric oxygen to from oxides of
sulphur . It is thereby recommended that plasma treatment systems are
installed in well ventilated areas to ensure that they pose no health
risks for the workers working in the surrounding environment.

CONCLUSION
 Plasma technology with all its challenges and opportunities, is an
unavoidable part of our future.
 The possibilities with plasma technology are immense and numerous.
 The synergy between plasma physics, engineering, chemistry ,surface
science, bio-science will provide unique opportunities.
 It can rightly be said that plasma technology is slowly, but steadily in the
industrial evolution.

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