PET Surface Properties affected by low temperature plasma modification

Tarek S. SalemTarek S. SalemPolymer Interface Department

Leibniz Institute for Polymer Research-Dresden

Mühlleithen / Vogtland, 10. -

12. March 2009E-Mail: Salem@ipfdd.de

•Poly(ethylene terephthalate) properties•Oxygen plasma pre-treatment•Subsequent treatment with polyelectrolytes•Textile Printing

2

High tensile strength , dimensional stability

Resistance to many chemicals

In Blends , PET makes the fabrics more resilient and wrinkle free

Poly(ethylene terphthalate) (PET) fabric

PET Surface Properties affected by low temperature plasma modification 

3

Crystal structure of poly(ethylene terephthalate)

R.H.Peters, the chemistry of fibers, Vol.1, Elseiver publications ,1963

Amorphous region

Crystalline region

Morphology of PET fibre

Encylopedia of polymer scienceand technology ©

2003

Motivations :Motivations :

PET Surface Properties affected by low temperature plasma modification 

4

Fibres& Textiles In eastern Europe April/june

2003, v.11, no.2 (41)

Motivations :Motivations :

Different classes of dyes

Moisture regain : 0.2-0.8 % at RH 65% , 20oC

Different textiles substrates

Textiles Ink-jet Printer

PET Surface Properties affected by low temperature plasma modification 

Printing pastes in traditional printing

5

Objective :Objective :

Surface modification of PET fabrics in order to open numerous

opportunities for improvement of

• wetting,

• printing behavior (substrate-independent printing)

without altering the mechanical / physical properties of the bulk materials .

PET Surface Properties affected by low temperature plasma modification 

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Strategy Strategy

Application of low temperature oxygen plasma to endow the PET surface with moieties of polar groups ( -COOH, -OH,..) . Such introduced oxygen-containing groups increase the surface free energy and enhance the fabric’s wettability, but they can also act as anchor for further surface modifications by weak polyelectrolytes

O

O

O

PET

O

OHO

OH-

Heat

CONH

+

O

O HO

O

PET Surface Properties affected by low temperature plasma modification 

++

+ ++ +

7

O

O

O

Gas inlet

Vacuum pump

Microwave generator2.45 GHz

PET

Tunable power(0-600 W) Excited gas species:

•Atoms•Molecules•Ions•Photons•Electrons•Free radicals•metastables

P-P-P-P P-P-

P-P-P-P- P-P-P

P-P-P-P P-P-P-P

P-P P

P-P-P-P

M M M

Crosslinking Etching (degradation) Functionalization

P : polymer chain

Plasma prePlasma pre‐‐treatmenttreatment

PET Surface Properties affected by low temperature plasma modification 

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Plasma power[W]

Plasma exposure time[s]

C [at %] O [at %]

0 0 69.68 25.76

100 15 63.66 34.32

100 30 57.58 38.89

300 15 61.92 36.03

300 30 57.12 39.25

XPS AnalysisXPS Analysis

PET Surface Properties affected by low temperature plasma modification 

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n ] [ 

280

O 1s

C 1s

1000 800 600 400 200 0Binding energy [eV]

Si 2sSi 2p

O 2s

a)

b)

O KLL

c)

300 290 280285295Binding energy [eV]

y

Hx

C

C-O-O=C

O-CC-O-CO=

π π*

H-O-CO=

H-O-CO=

CO=

CO=

Untreated PET

Plasma treated at 300 W 15 s

CC

OO

OCH2CH2O

PET Surface Properties affected by low temperature plasma modification 

Plasma treated at 100 W 15 s

XPS AnalysisXPS Analysis

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A possible mechanism of plasma functionalization for PET fiberA possible mechanism of plasma functionalization for PET fiber

Active plasma species

O O

O

OCC

O O

CC O

O

(I) (II)1 2

O

(III)(IV)O O

OCC

Active plasma species

H (I)

C

O

C HOCH2CH2O

(I)O2

O CH2 CH2 O OCO

C O

H

CO

C OOCH2CH2O OH

CO

C OOCH2CH2O

CO

C OHOCH2CH2O

H

(II)-H

CH OCH2O

(IV)

CH2CH2O OH

OH

A.Perwuelz, J. Adhesion Sci.Technol ., Vol.20, No. 9, PP.939 ( 2006)

PET Surface Properties affected by low temperature plasma modification 

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ZetaZeta--Potential (Potential (ζ)

Presentation of the electrochemical double layer according to the Gouy-Chapman-Stern-Grahame (GCSG) model

C.Werner, H.J. Jacobasch, J.Biomater. Sci. Polym.Edn 7 (1995) 1.

INLET OUTLET

Fabric sample 1

Fabric sample 2

Streaming channel

ElectrodeElectrode

PTFE foilLower part

Lower part

Zeta-potential measuring cell for fabrics

+-

-

- +

+

-

distance z

surfaceImmobile layer

mobile layer

Hydrated cation

Hydrated anion

OHPIHP

Shear plane

0

ζ

IHPΨ

OHPΨ

PET Surface Properties affected by low temperature plasma modification 

IEP= pH|ζ=0

Q RUs∆P

ηεεo

L 1ζ =

Smoluchowski equation :

H.J.Jacobasch, F.Simon, C.Bellmann, Techn.Messen Sensoren Geräte syst. 63, 447 (1996)

O

O

O

O

OHO

OH

-

ZetaZeta--Potential (Potential (ζ)

PET Surface Properties affected by low temperature plasma modification 12

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Wettability measurments on fabricsWettability measurments on fabrics

Water Uptake Water drop absorption timeWeight

TimeWetting

Capillarity

1

2

Typical wetting curve

Liquid

Textile sample

F

PET Surface Properties affected by low temperature plasma modification 

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Water drop absorption time

T

abs

> 600 s

Untreated PET

Plasma Pre-treated PET

T

abs

= 0.039 -

0.024 s

PET Surface Properties affected by low temperature plasma modification 

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Roughness measurmentsRoughness measurments

Untreated PET Plasma treated 300 W, 30 s

Ra

= 24,8 µm Ra

= 27,3 µm

PET Surface Properties affected by low temperature plasma modification 

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O

OHO

OH

Subsequent treatment with polyelectrolytesSubsequent treatment with polyelectrolytes

OHOO

NH2

OH

OO

OH

O

HO NH

COCH3

O

H2N

OH

HO

O

NH2

NH2

Chitosan

1. Adsorption2. Dryeing3. Annealing

NH2NH2

NH2

COO COONH3

NH3

NHC O

NH2

NH3

PET Surface Properties affected by low temperature plasma modification 

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NH2

NH2NH2NH2

NH2

O

O

O

O

OHO

OH

ZetaZeta--Potential (Potential (ζ)

PET Surface Properties affected by low temperature plasma modification 

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Plasma power[W]

Plasma exposure time

[s]C [at %] O [at %] N [at %]

0 0 69.68 25.76 ----

300 30 57.12 39.25 ----

XPS AnalysisXPS Analysis

Chitosan treated 62.23 33.06 2.65

PET Surface Properties affected by low temperature plasma modification 

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O

O

N

N

SO 3N a

SO 3N a

H

H

NH2

NH2NH2NH2

NH2

Textile Textile printingprinting

H+

+ +++

+ + +

D

SO3-

D

SO3-

D

SO3-

Wave length

(nm)

K/S

Untreated

PET+Chitosan

Plasma treated

PET+ChitosanC.I. Acid Blue 80

PET Surface Properties affected by low temperature plasma modification 

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OutlookOutlook

1.Oxygen

plasma

pre-treatment

confer

wettability

properties

to the

PET fabric.

2.XPS, Zeta

potential, and wettability

measurements

results

evidence

that the

formation

of new

functional

groups

on the

PET surface

could

be

attributed

to the

oxidation

of the

poly(ethylene

terephthalate) forming fibre.

3. Polar functional

groups, introduced

during

plasma

pre-treatment, were considered

as anchor

groups

for

adsorption

of chitosan, and its

further

grafting

through

the

heat-induced

reactions.

4. Significant

changes

in PET surface

properties

after

chitosan

coating formation

were

detected

by

the

increase

the

colour

strength

after

printing

with

acid

dye

and electrokinetic

measurement, which

showed

that

the modified

PET had

isoelectric

point shifted

to higher

pH

(7.7)

PET Surface Properties affected by low temperature plasma modification 

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Acknowledgement

1. Dr.Frank

Simon2. Dr.Mirko

Nitschke

3. Dr.Rolf-Dieter

Hund 4.Mr. Dieter Pleul5.Mr. Alfredo Clavimontes6.Mrs.Steffi Uhlmann7.Mrs.Anja Caspari8.Mrs.Katharina Fink

Leibniz Institute for Polymer Research-Dresden e.V. (Germany)Cultural

Affairs & Mission sector

–

Minstry

of higher

education

( Egypt)

PET Surface Properties affected by low temperature plasma modification