Download - Aatcc Meeting 2008 Khk
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Plasmas are generated in gases by heating, byapplying a voltage, or by injectingelectromagnetic waves.
Electrical discharges commonly used
Generation of Plasma
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The ignition is brought about by the small fraction
of charged particles always present in the gas.
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Emission of characteristic
glow when it comes to
ground state
Electron interactions in plasma
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PROPAGATION
GENERATION
LOSS OFELECTRONES
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Plasma Species determine the plasma type
Electron density
Ion density
Electron/ion temperatureInteractions between electron-electron, ion-
electron, ion-ion etc are possible
Plasma exhibit broad range of spectrum i.e
electron density from few to 1025
/cm3
Different mean path length
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System pressure
Electrode configuration
Nature of gasFlow rate of gas
Power
Time of treatment
Nature of substrate
PLASMA PROCESS PARAMETERSPLASMA PROCESS PARAMETERS
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PLASMA Dependency on System Pressure
To initiate and sustain the plasma
continuous supply of energy is must.
Vb= f (p .d)
At fixed applied voltage, d must decrease, as weincrease the pressure
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Electrode configuration and features
Presence of DielectricPresence of DielectricBarrierBarrier
Spacing between theSpacing between the
electrodeselectrodes
Geometry ofGeometry of
electrodeselectrodes
Symmetry ofSymmetry of
electrodeselectrodes
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The type of gas determines the nature of interactionbetween the substrate and the plasmai.e. etching, grafting, polymerisationBreakdown energy necessary to produce plasma varies
Inert gasesInert gasesHe, Ar are commonly used .These are used for cleaning, activation purposeThey act as diluting media for reactive gas
Oxygen containing plasmaOxygen containing plasma:Importance of reactive gas in surface modificationscan react with wide range of polymersImpart various functional groups like c-o, c=o, o-c-o,c-o-o etc
Types of Gas UsedTypes of Gas Used
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Fluorine containing plasmaFluorine containing plasma :CFx etching and polymerisation
HydrocarbonsHydrocarbons : methane, ethane, ethylene to generate plasma polymerised
hydrocarbon film to impart microhardness, optical refractive index and
impermeability
Organosllicone monomers :
excellent thermal and chemical resistance
Nitrogen containing plasma to improve wettability, printability
biocompatibility of the substrate
Types of Gas Used contd..Types of Gas Used contd..
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Why Helium in glow discharges?
Media for uniform glow discharge and carrier of
reactive gases
Mean free path
Possibility of collisions
Meta stable state configuration
Simple energy levels
Thermal conduction properties support theuniform discharge
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Discharge power SupplyDischarge power SupplyThe energy required to generate plasma depend on
the nature of gas and equipment
Higher power means high kinetic energy of the
reactive speciesOptimization depends with the substrate and
system parameters
Duration of treatment
The extent of treatment can be varied with time
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Polyester/cotton blended textiles
Why treatment of P/C blended textiles?
Treatment carried out at Textile Chemistry,Science and Engineering department of NCSU,
Raleigh, USA.
Hydrophilic textiles with AtmosphericHydrophilic textiles with AtmosphericPressure PlasmaPressure Plasma
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ObjectivesObjectives
1. To impart hydrophilicity to the textiles withatmospheric pressure plasma
2. To assess the effect of plasma treatment withmeasurement of wicking behaviour and surface
characteristics3. To study influence of following process variables
Intensity of Glow Discharge (Power Supply)Duration of Treatment
Nature of GasGas concentration (Flow rate)Distance between substrate and electrode
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Fabric: Polyester/cotton blended RFD fabric
Blend composition 67/33
epi / ppi : 90/70GSM: 88
Machine: Atmospheric Pressure Glow Discharge
at RF 13.56 MHz
Materials and methods
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Atmospheric Pressure Glow Dischargeat RF 13.56 MHz
RF generator
Electrodes
Gas input
Evaporator
Cooling for
system
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Assessment of Efficiency of Hydrophilic Treatment
Capillary rise up to 30 min
Interval of measurement of height-every
5 min.
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He : 40 LPMHe : 40 LPM
OO22 : NIL: NIL
D: 0.13D: 0.13
T: 25 secT: 25 sec
Height of capillary rise (cm)
wicking time 5 min 10 min 15 min 20 min 25 min 30 min
Discharge
Intensity
(Watts)
C 0.4 0.9 1.4 1.7 2.1 2.4
400 0.6 1.35 1.85 2.5 2.9 3.3
500 0.9 1.65 2.35 2.85 3.45 3.95
600 0.9 2 2.7 3.4 4.3 5700 0.85 1.5 2.6 3.35 4.1 4.8
Discharge Intensity v/s Wicking HeightDischarge Intensity v/s Wicking Height
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Role of Discharge Intensity of He Plasma with ORole of Discharge Intensity of He Plasma with O22
Height of capillary rise (cm)
Wicking time 5 min
10min
15min
20min
25min
30min
Intensity of
Discharge
(Watts)
C 0.4 0.9 1.4 1.7 2.1 2.4
400 2.3 3.35 4.25 4.95 5.45 6.1
500 2.45 3.45 4.3 5.35 5.95 6.6
600 3.2 4.55 5.35 5.9 6.3 7
700 3.6 4.55 5.4 6.05 6.6 7.1
He : 40 LPMHe : 40 LPM
O2 : 0.15 LPMO2 : 0.15 LPM
D: 0.13D: 0.13
T: 25 secT: 25 sec
effect of o er on ca i ary rise
0
1
2
3
45
6
7
400 500 600 700
Po er (Watts)
HeightofCa
iary
ise(c
5 min
10 min15 min
20 min
25 min
30 min
n
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Height of capillary rise (cm)
Wicking time 5 min 10 min 15 min 20 min 25 min 30 min
Treatment
Time
(sec)
C 0.4 0.9 1.4 1.7 2.1 2.4
14 0.5 0.95 1.55 1.9 2.4 2.7
20 1.1 2.1 2.9 3.75 4.6 5.3
25 1.5 2.55 3.35 4.2 4.8 5.35
37 2. 4 4.1 5.4 6.4 7 7.7
He : 40 LPMHe : 40 LPM
O2 : NILO2 : NIL
P: 650 wattsP: 650 watts
D: 0.13D: 0.13
Effect of Duration of TreatmentEffect of Duration of Treatment
Helium Plasma inHelium Plasma in
absence ofabsence ofoxygenoxygen
effect of treatment time on capilary rise
0
1
2
3
4
5
6
7
8
9
C 14 20 25 37
treatment time (sec)
HeightofCapilary
Rise(cm)
5 min
10 min
15 min
20 min
25 min
30 min
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Height of capillary rise (cm)
wicking time 5 min 10 min 15 min 20 min 25 min 30 min
Treatment
time
(sec)
C 0.4 0.9 1.4 1.7 2.1 2.4
14 1.1 2.2 3.3 4.3 5 5.85
20 1.6 2.9 3.7 4.6 5.3 5.9
25 2 3.7 4.7 5.65 6.15 6.6
37 2.65 3.8 5 5.8 6.4 7.5
He : 40 LPMHe : 40 LPM
O2 : 0.15 LPMO2 : 0.15 LPM
P: 650 wP: 650 w
D: 0.13D: 0.13
Effect of Duration of Treatment in Presence of OEffect of Duration of Treatment in Presence of O22
Helium Plasma inHelium Plasma in
presence ofpresence ofoxygenoxygen
effect of treatment time on capilary rise
0
1
2
3
4
5
6
7
8
C 14 20 25 37
treatment time (sec)
HeightofCapilaryRise(
5 min
10 min
15 min
20 min
25 min
30 min
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Height of capillary rise (cm)
wicking time 5 min 10 min 15 min 20 min 25 min 30 min
He flow rate
LPM
13 0.65 1.9 2.4 3.15 3.7 4.1
22 1.5 2.4 3.4 3.8 4.2 4.6
30 2 3.5 4.45 5.15 5.6 6.15
40 1.4 2.6 3.65 4.4 5 5.5
50 1.2 2.1 2.9 3.3 4.45 4.9
60 0.7 1.4 2.3 3.1 3.5 4
P: 650 w
O2 : NIL
D: 0.13
T:25 sec
Effect of Gas Concentration
He plasma in
absence ofoxygen
effect f l te
0
1
2
3
4
5
6
7
13 22 31 40 52 60
Gas l
ate ( )
ei
t
f
apilar
ise(cm)
5
i
10
i
15
i
20
i
25
i
30
i
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Height of capillary rise(cm)
wicking time
5
min 10 min 15 min 20 min 25 min 30 min
He flow rate
LPM
30 2 2.9 3.6 4.1 4.5 4.9
40 2.4 3.4 4.3 5.1 5.7 6.3
50 2.7 3.8 4.9 5.5 6 6.560 2.45 3.35 4.4 4.9 5.45 5.8
P: 650 w
D: 0.12
T:25 sec
O2 : 0.15 LPMO2 : 0.15 LPM
Effect of Gas Concentrationwith Oxygen
Helium Plasma inHelium Plasma inpresence ofpresence ofoxygenoxygen
e ec Gas Ra e
0
1
2
3
4
5
6
7
35 40 52 60
Gas
Ra
e
P
He
Ca
ay
Rse
c
5 !"
n
10 !"
n
15 !"
n
20 !"
n
25 !"
n
30 !"
n
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Height of capillary rise (cm)
wicking time 5 min 10 min 15 min 20 min 25 min 30 min
Electrode
distance
(inch)
0.10 2.5 3.6 4.5 5.5 6.2 6.6
0.11 2.1 3.1 3.8 4.4 5 5.7
0.12 1.2 2.2 3 3.7 4.3 4.9
0.13 0.9 1.85 2.6 3.4 4.1 4.70.14 0.8 1.7 2.4 3.3 4 4.6
0.15 0.7 1.4 2 2.6 3.1 3.8
effect of Electrode distance
0
1
2
3
4
5
6
7
0.10 0.11 0.12 0.13 0.14 0.15
Electrode istance (inch)
Heightof
apilaryRi
se(cm)
5 min
10 min
15 min
20 min
25 min
30 min
P: 600 W
He: 40
T: 25 sec
Effect of Distance between Substrate andElectrode
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Height of capillary rise(cm)wicking time 5 min 10 min 15 min 20 min 25 min 30 min
Electrode
distance
(inch)
0.11 3.1 4.4 5.3 5.9 6.5 6.95
0.12 2.6 3.7 4.5 5.15 5.55 5.9
0.13 2.2 3.3 4.3 4.9 5.4 5.7
0.14 2 2.6 3.6 4.25 4.7 5.1
effect of Electrode distance
0
1
2
3
4
5
6
7
0.11 0.12 0.13 0.14
Electrode Distance (inch)
HeightofCapilaryRise(cm)
5 min
10 min
15 min
20 min25 min
30 min
P: 600 WP: 600 W
O2 : 0.15 LPMO2 : 0.15 LPM
P: 600P: 600
Effect of Electrode SpacingEffect of Electrode Spacing
Helium Plasma inHelium Plasma inpresence ofpresence ofoxygenoxygen
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Gas composition and Power AppliedGas composition and Power Applied
0
1
2
3
4
400 500 600 700
powe applie wa s
wickingheight(cm
with e iu on
with e iu and gen
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Gas composition and Duration of TreatmentGas composition and Duration of Treatment
0
0.5
1
1.5
2
2.5
3
14 20 25 37
time o treatment sec
ic
kingheiht
cm)
i h eliu onl
i h eliu and O gen
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0
0.5
1
1.5
2
2.5
33.5
0.11 0.12 0.13 0.14
electrode distance) inch)
wickingheight(c
with Helium only
with Helium and Oxygen
Gas composition and electrode spacingGas composition and electrode spacing
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Plasma treatment can modify the textile surfacePlasma treatment can modify the textile surfaceto impart the hydrophilic propertiesto impart the hydrophilic propertiesIncrease in duration of treatment and intensityIncrease in duration of treatment and intensityof Plasma led to more hydrophilicityof Plasma led to more hydrophilicity
Increase in Gas flow rate showed initially increaseIncrease in Gas flow rate showed initially increasein hydrophilicity and then decreasein hydrophilicity and then decreaseAt given applied power (Intensity), the increase inAt given applied power (Intensity), the increase inelectrode spacing has negative effect onelectrode spacing has negative effect onhydrophilicityhydrophilicity
Addition of little amount of oxygen hasAddition of little amount of oxygen hassignificant effect on the hydrophilic propertiessignificant effect on the hydrophilic properties
Concluding RemarksConcluding Remarks
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