PHOTOSENSITISED GRAFT COPOLYMERIZATION

OF ACRYLIC ACID ONTO CARBOXYMETHYL

STARCH

M.A. ElSheikh*, J.T. Guthrie* and A. Waly**

University of Leeds, Colour Chemistry Dept.,

Leeds, LS2 9JT, UK

**National Research Center, Textile Research

Division, Dokki, Cairo, Egypt.

*Address in UK *Address in Egypt

University of Leeds, National Research Center

Colour Chemistry Dept. Textile Research division

Leeds, LS2 9JT, UK Dokki, Cairo, Egypt

Tel. : 00441132332939 Tel. : 002023371211-4960

Fax : 00441132332947 Fax : 002023370931

Email : CCDMAE@LEEDS.AC.UK

2

Contents

Introduction

Why UV

High Graft Yield

Efficient use of materials (low

homopolymer under right circumstances)

Mild Effect relative to chemical initiation

methods

Simple processing

Cost effective

Water-based options

3

Experimental

• Materials

• CMS, laboratory prepared

• Acrylic Acid(AA), Ethanol, and4 trimethyl

ammonium methyl benzophenone chloride

(photoinitiator) was laboratory Grade.

• Water: distilled

• UV source, Philips lamp, 125 w/inch, medium

pressure.

4

Preparation of Poly(acrylic acid)- CMS

Sample handling

Grafting

Carboxymethyl Starch (CMS) [prepared from

Native Starch (NS)], DS=0.2, [-COOH] = 115

mmole/100g CMS and η= 158 mPa s.

CMS was in the form COONa.

Photoinitiator (PI) dissolved in the required amount

of water.

CMS added gradually under continuous stirring

and left till completely soluble.

Acrylic Acid (AA) added gradually under

continuous stirring and left for 10 min.

5

Mixture was transferred to a photochemical reactor

and subjected to UV source under gentle stirring

for known time periods.

Reaction stopped.

Homopolymer separated from the graft copolymer.

6

Analysis

All samples monitored for Total Conversion percent

(TC%) of Acrylic Acid and for their Carboxyl

Content (-COOH, mmole/100g CMS)

Selected samples monitored by:

SEM

Thermal Analysis (DSC)

IR spectroscopy

7

Reaction Mechanism

PI exited state

PI operated by H-abstraction from this exited state.

PI designed to bind to starch, i.e. H-abstraction

involves starch.

Radicales formation by C----H homolytic cleavage on

starch backbone.

Grafting occurs at the radical centers.

Little homopolymerization since the bulk of the PI is

on the starch polymer chain.

8

Results and Discussion

Factors Affecting Total Conversion and

COOH content:

Studies

Effect of PI concentration.

Effect of Acrylic Acid concentration

Effect of Material : Liquor ratio

Effect of reaction temperature

Effect of reaction Time.

9

Effect of Photoinitiator Concentration on the Carboxyl Content of the Grafted CMS

0

50

100

150

200

250

300

350

0 10 20 30 40 50 60 70PI %(OWS)

5g CMS, DS=0.2, COONa= 115 (mmole/100g CMS), η=158 (mPa s); AA, 60% (OWS); M:L

Ratio, 1:50; Room Temperature; Time, 3h.

CO

OH

con

tent

(mm

ole/

100g

CM

S)

10

Effect of Photoinitiator Concentration on the Total Conversion (%) of Acrylic Acid

0

20

40

60

80

100

0 10 20 30 40 50 60 70PI %(OWS)

5g CMS, DS=0.2, COONa= 115 (mmole/100g CMS),η=158 (mPa s); AA, 60% (OWS); M:L

Ratio, 1:50; Room Temperature; Time, 3h.

TC

%

11

Effect of Acrylic Acid Concentration on the Carboxyl Content of Grafted CMS

0

100

200

300

400

500

600

700

0 20 40 60 80 100 120 140 160Acrylic Acid % (OWS)

5g CMS, DS=0.2, COONa= 115 (mmole/100g CMS),η=158 (mPa s); M:L Ratio, 1:50; Room

Temperature; PI, 10% (OWS); Time, 3h.

CO

OH

Con

tent

(mm

ole

/ 100

g C

MS)

12

Effect of Acrylic Acid Concentration on the Total Conversion (%) of Acrylic Acid

0

20

40

60

80

100

0 20 40 60 80 100 120 140 160Acrylic Acid (%)

5g CMS, DS=0.2, COONa= 115 (mmole/100g CMS),η=158 (mPa s); M:L Ratio, 1:50; Room

Temperature; PI, 10% (OWS); Time, 3h.

TC

(%)

13

Effect of Material : Liquor Ratio on the Carboxyl Content of Grafted CMS

1:20

1:30 1:40

1:60 1:70 1:80

0

100

200

300

400

500

600

700

M:L Ratio

5g CMS, DS=0.2, COONa= 115 (mmole/100g CMS),η=158 (mPa s); Room Temperature; PI,

10% (OWS); AA, 150% (OWS); Time, 3h.

CO

OH

Con

tent

(meq

/ 10

0g C

MS)

14

Effect of Material : Liquor Ratio on The Total Conversion (%) of Acrylic Acid

1:20

1:30

1:40

1:70

1:80

0

20

40

60

80

100

M:L Ratio

5g CMS, DS=0.2, COONa= 115 (mmole/100g CMS),η=158 (mPa s); Room Temperature; PI,

10% (OWS); AA, 150% (OWS); Time, 3h.

TC

(%)

15

Effect of Temperature on the Carboxyl Content of Grafted CMS

400

450

500

550

600

650

700

0 10 20 30 40 50 60 70 80 90Temperature oC

5g CMS, DS=0.2, COONa= 115 (mmole/100g CMS),η=158 (mPa s); PI, 10% (OWS); AA, 150% (OWS); M:L Ratio, 1:30; Time, 3h.

CO

OH

Con

tent

(mm

ole/

100g

CM

S)

16

Effect of Temperature on the Total Conversion (%) of Acrylic Acid

30

40

50

60

70

80

90

100

110

0 10 20 30 40 50 60 70 80Temperature oC

5g CMS, DS=0.2, COONa= 115 (mmole/100g CMS),η=158 (mPa s); PI, 10% (OWS); AA, 150% (OWS); M:L Ratio, 1:30; Time, 3h.

TC

(%)

17

Effect of Reaction Time on The Carboxyl Content of the Grafted CMS

0

100

200

300

400

500

600

700

0 1 2 3 4 5 6 7Time (h)

5g CMS, DS=0.2, COONa= 115 (mmole/100g CMS),η=158 (mPa s); PI, 10% (OWS); AA, 150% (OWS); M:L Ratio, 1:30; Temp. 30oC.

CO

OH

Con

tent

(mm

ole/

100g

CM

S)

18

Effect of Reaction Time on the Total Conversion (%) of Acrylic Acid

0

20

40

60

80

100

0 1 2 3 4 5 6 7Time (h)

5g CMS, DS=0.2, COONa= 115 (mmole/100g CMS),η=158 (mPa s); PI, 10% (OWS); AA, 150% (OWS); M:L Ratio, 1:30; Temp. 30oC.

TC

(%)

19

Optimum conditions

Photoinitiator, 10% (OWS)

Acrylic Acid, 150% (OWS)

Material : Liquor Ratio, 1:30.

Reaction Temperature, 30oC.

Reaction Time, 4 hours.

20

Characterization

-COOH Content

COOH content due to grafting using

UV/photoinitiation reaches 600 mmole/100g CMS

at optimum conditions compared by 87

mmole/100g CMS using Chemical initiation (see

part II).

Homopolymer formation minimal.

21

Characterization SEM

SEM of: a, NS; b, CMS* and c, poly(AA)-CMS* graft copolymer

NS, CMS* and CMS*-PAA

b

a

c

22

Characterization Thermal Analysis (DSC)

DSC curves of: NS, control CMS* and poly(AA)-CMS* graft copolymer

NS, CMS* and CMS*-PAA

NS

Control CMS*

Poly(AA)-CMS*

23

Characterization IR spectroscopy

IR spectra of: NS, control CMS* and poly(AA)-CMS* graft copolymer

NS, CMS, CMS-PAA and PAA

NS

Control CMS*

poly(AA)-CMS*

24

Advantages of the polymerization process

used High viscosity of the composite achieved.

High adhesion of the composite achieved.

High Swelling in water of the dry composite or dry

graft copolymer achieved.

High graft yield, low homopolymer formed.

Mild conditions used to get high quality product.

Trials will be done to use the sun light instead of Hg

lamp as a source of UV.

Conclusion The process can be recommended for providing

CMS-PAA graft copolymer with high graft yield.

25

Applications

Sizing agents in the paper and textile

industries.

Printing thickeners for pigment

dispersions.

Adhesives.

Ion exchange materials.

26

Acknowledgments

Egyptian Government for funding the research at

Leeds University.

Egyptian Government for providing funds for

attendance at the American Chemical Society

Meeting in San Francisco.

Professors in National Research Center (NRC),

Textile Research Division (TRD) and University of

Leeds, Colour Chemistry Dept. for supervision:

Prof. Dr. J.T. Guthrie (University of Leeds, Colour

Chemistry Dept.)

Prof. Dr. A. Waly (NRC, TRD)