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SYNTHESIS AND CHARACTERIZATION OF
NEW POLYMERIC MATERIALS BASED ON
WATER SOLUBLE STARCH COMPOSITES
M.A. ElSheikh*, A. Hebeish, A. Waly, M.H.
ElRafie and J.T. Guthrie**
National Research Center, Textile Research
Division, Dokki, Cairo, Egypt.
** University of Leeds, Colour Chemistry Dept.,
Leeds, LS2 9JT, UK
*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 : [email protected]
2
Contents
Part I:
Preparation and Characterization of Carboxymethyl
Starch (CMS)
Part II:
Graft copolymerisation of Acrylic Acid onto
Carboxymethyl Starch Using Chemical Initiation
.......................
Part III:
Graft copolymerisation of Acrylic Acid onto
Carboxymethyl Starch Using Photo Initiation
3
Part1: Preparation and Characterization of
Carboxymethyl Starch (CMS) Introduction
Why CMS
Solubility
Viscosity
wide Application
Experimental
• Materials
• starch
• Native Starch (NS
• Hydrolyzed Starch (
) η= 239 (mPa S)
HS
• Highly Hydrolyzed Starch (
), η=134(mPa S)
HHS
η = 61(mPa S)
),
• NaOH, Na2Co3 , Ethanol (commercial
Grade)
• ClCH2COOH, Laboratory Grade
4
Carboxymethylation
• ClCH2COOH reacts with Na2Co3 to form
ClCH2COONa.
• Starch is stirred with NaOH in Ethanol/Water
mixture.
• Starch [St.-(OH)] reacts with ClCH2COONa in
presence of NaOH to form Carboxymethyl Starch
(CMS).
• 2 ClCH2COOH + Na2CO3 2 ClCH2COONa + H2O+
CO2
• St.-OH + ClCH2COONa + NaOH St-OCH2COONa
+NaCl + H2O
CMS is separated from the liquor by filtration,
washed with 80% Ethanol and dried.
5
Viscosity(η) and Degree of Substitution (DS)
• NS, HS and HHS
• Three concentrations of ClCH2COOH, Na2Co3 and
NaOH, based on theoretical calculations of DS (0.1,
0.3 and 0.5), were used for each Starch sample.
were used to provide CMS with
different viscosity.
• Nine CMS samples were prepared for the study
• Three from NS
• Three from
with theoretical DS of 0.1, 0.3
and 0.5
HS
• Three from
with theoretical DS of 0.1, 0.3
and 0.5
HHS
with theoretical DS of 0.1, 0.3
and 0.5
6
More CMS Samples
• 5 kg. Of CMS from NS with theoretical DS of
0.3 was prepared for further study and
applications symbolized by “
CMS*”
• 1 kg. Of CMS from NS with theoretical DS of
0.5 was prepared for further study and
applications symbolized by “CMS**
”
7
Analysis and Characterization
In comparison with NS.
All the CMS samples were analyzed to determine:
• Total Carboxyl content (mmole/100g CMS)
• DS
• Viscosity at different shear rates (mPa s)
CMS* and CMS**
• Rheological properties
were analyzed to determine:
• Change in surface structure using SEM
• Thermal behavior using DSC
8
Results and Discussion
• All samples prepared using theoretical DS of 0.1
gave CMS with DS ~ 0.04 regardless the viscosity
of the starch used.
• All samples prepared using theoretical DS of 0.3
gave CMS with DS ~ 0.2 regardless the viscosity of
the starch used.
• All samples prepared using theoretical DS of 0.5
gave CMS with DS ~ 0.4 regardless the viscosity of
the starch used.
• Viscosity of the prepared CMS depends on the
starch used.
9
Characteristics of CMS prepared from starch with different levels of
hydrolysis (NS, HS and HHS
; η = 239, 134 and 61 (mPa s) respectively)
Theoretical
Practical DS
- COOH Content
( mmole/100g CMS)
η
(mPa s)
Solubility
in cold water
NS, HS, HHS NS HS HHS NS HS HHS NS HS HHS NS HS HHS
0.1
0.046 0.044 0.038 28 26.7 23.2 134.2 38.7 10.5 slightly soluble
0.3 0.191 0.199 0.211 110.4 111.8 121.2 169.2 70 18.1 completely
soluble 0.5 0.393 0.388 0.343 210.2 188.6 198.6 198.3 212.3 31.5 completely
soluble
10
Effect of Degree of Substitution of CMS on its Viscosity
0
50
100
150
200
250
0 0.1 0.2 0.3 0.4 0.5DS
Vis
cosi
ty (m
Pa s)
CMS from NS
CMSfrom HS
CMS from HHS
11
Effect of the Degree of Substitution of CMS on its Viscosity measured at Different Rates of
Shear
0
100
200
300
400
500
600
700
800
0 150 300 450 600 750 900 1050 1200 1350Rate of Shear (s-1)
Vis
cosi
ty (m
Pa s)
CMS (DS=0.046, NS)CMS (DS=0.044,HS)CMS (DS=0.038, HHS)CMS (DS=0.191, NS)CMS (DS=0.199,HS)CMS (DS=0.211, HHS)CMS (DS=0.393, NS)CMS (DS=0.388,HS)CMS (DS=0.343, HHS)NSHHS
12
NS, CMS* and Samples Chosen:
CMS**
• NS: DS = 0.0, η=239 (mPa s)
• CMS*: DS= 0.2, η=158 (mPa s), from NS
• CMS**: DS= 0.4, η=198 (mPa s), from NS
13
Characterization
• Rheology
• V1; viscosity on applying mechanical stress
• V2; viscosity on removing mechanical stress
• SEM
• Thermal Analysis (DSC)
14
Effect of the Extent of Carboxymethylation on the Rheological Properties of CMS
0
100
200
300
400
500
600
700
0 200 400 600 800 1000 1200 1400
Rate of Shear (s-1)
Vis
cosi
ty (m
Pa s)
V1 (NS, DS=0.0) V2 (NS, DS= 0.0)V1 (CMS*, DS= 0.2)V2 (CMS*, DS= 0.2)V1 (CMS**, DS= 0.4)V2 (CMS**, DS= 0.4)
15
SEM
a, NS; b, CMS*; and c, CMS**
NS, CMS* and CMS**, Powder Form
16
DSC
a
b
c
a, NS; b, CMS*; c, CMS**
NS, CMS* and CMS**, Powder Form
17
Advantages of the carboxymethylation
process used
• Homogeneous distribution of the reactants.
• No heat of reaction.
• No excess alkali (pH after carboxymethylation~8)
• Replication (same DS at same conditions)
• High reaction efficiency for higher DS
• 0.1 ~ 0.04 (40%)
• 0.3 ~ 0.2 (66.7%)
• 0.5 ~ 0.4 (80%)
• Recycling of Ethanol for purification.
Applications:
• Sizing agents in the paper and textile industries.
• Printing thickeners for pigment dispersions.
• Adhesives.
• Ion exchange materials.
18
Part II: Graft copolymerisation of Acrylic
Acid onto Carboxymethyl Starch Using
Chemical Initiation
Introduction
Aim
Water soluble polymer
High carboxyl content
Industrially applicable
Experimental
• Materials
• CMS, laboratory prepared (Part1)
• Acrylic Acid (AA), Potassium Bromate and
Thiourea dioxide (TUDO) are laboratory
grade.
• Ethanol, commercial grade.
19
Preparation of Poly(acrylic acid)- CMS
• Sample handling
• Grafting
• All used CMS were in the form -COONa
• Cooking
• Cooling to the reaction temperature
• Adding TUDO under continuous stirring
• Adding AA under continuous stirring
• Adding KBrO3 under continuous stirring
• Left for the required time
• Separation of homopolymer
20
• Analysis
• All samples were monitored to Total
Conversion % (TC%) of Acrylic Acid
• Selected samples were monitored to:
• -COOH content (mmole/100g CMS)
• SEM
• Thermal Analysis (DSC)
21
Reaction Mechanism
Here, x (= n-6) is the number of electrons contributed from the reaction medium.
The isothiourea dioxide radicals (I) attack the starch chain to form starch free radicals (II)
(Reaction 3.3)
Furthermore, the isothiourea dioxide radicals can strongly initiate hompolymerisation of the
acrylic acid monomer molecules (Reaction 3.4). Thus:
22
The reaction of starch free radicals with the acrylic acid monomer initiates the grafting reaction
along the starch backbone (Reaction 3.5).
initiation
propagation
(3.5)
23
Results and Discussion
Factors Affecting Total Conversion %
Studied:
• Effect of Material : Liquor ratio.
• Effect of TUDO concentration, mmole/100g
CMS.
• Effect Redox system concentration
mmole/100g CMS.
• Effect of reaction temperature, oC.
• Effect of Acrylic Acid concentration, “%
(OWS)” (% based On Weight of Substrate)
• Effect of DS and viscosity(mPa s) of the used
CMS.
• Reaction time.
24
Effect of M:L Ratio on TC% of Acrylic Acid
0
20
40
60
80
100
0 20 40 60 80 100
Time (min.)
CMS, (DS= 0.199), (η= 70 mPa s); AA, 30%(OWS); Temp., 40oC; [(KBrO3)/(TUDO)],
6/6 mmole/100g CMS.
TC
%
01:0301:0401:0501:06
25
Effect of M:L Ratio on TC% of Acrylic Acid
1:3 1:41:5
1:6
0
20
40
60
80
100
M:L Ratio
CMS, (DS= 0.199), (η= 70 mPa s); AA, 30%(OWS); Temp., 40oC; [(KBrO3)/(TUDO)],
6/6 mmole/100g CMS; Time, 90 min.
TC
%
26
Effect of TUDO Concentration on TC% of Acrylic Acid
0
20
40
60
80
100
0 20 40 60 80 100Time (min.)
CMS, (DS= 0.199), (η= 70 mPa s); AA, 30%(OWS); Temp., 40oC; M:L Ratio, 1:5;
[KBrO3],6 mmole/100g CMS.
TC
%
2 mmole/100g CMS4 mmole/100g CMS6 mmole/100g CMS8 mmole/100g CMS10 mmole/100g CMS
27
Effect of TUDO Concentration on TC% of Acrylic Acid
0
20
40
60
80
100
0 2 4 6 8 10 12[TUDO] mmole/100g CMS
CMS, (DS= 0.199), (η= 70 mPa s); AA, 30%(OWS); Temp., 40oC; M:L Ratio, 1:5; [KBrO3],6 mmol/100g CMS; Time, 90 min.
TC
%
28
Effect of Initiator Concentration [(KBrO3)/(TUDO)] mmole/100g CMS on
TC% of Acrylic Acid
0
20
40
60
80
100
0 20 40 60 80 100
Time (min.)
CMS, (DS= 0.199), (η= 70 mPa s); AA, 30%(OWS); Temp., 40oC; M:L Ratio, 1:5.
TC
%
3/3 mmole/100g CMS4/4 mmole/100g CMS5/5 mmole/100g CMS6/6 mmole/100g CMS7/7 mmole/100g CMS8/8 mmole/100g CMS
29
Effect of Initiator Concentration [(KBrO3)/(TUDO)] mmole/100g CMS on
TC% of Acrylic Acid
3/3 4/4
5/56/6 7/7
8/8
0
20
40
60
80
100
[(KBrO3)/(TUDO)] mmole/100g CMS
CMS, (DS= 0.199), (η= 70 mPa s); AA, 30%(OWS); Temp., 40oC; M:L Ratio, 1:5; Time,
90 min.
TC
%
30
Effect of Temperature on TC% of Acrylic Acid
0
20
40
60
80
100
0 20 40 60 80 100
Time (min.)
CMS, (DS= 0.199), (η= 70 mPa s); AA, 30%(OWS); M:L Ratio, 1:5; [(KBrO3)/(TUDO)],
6/6 mmole/100g CMS.
TC
%
30405060
31
Effect of Temperature on TC% of Acrylic Acid
0
20
40
60
80
100
0 10 20 30 40 50 60 70Temperature (oC)
CMS, (DS= 0.199), (η= 70 mPa s); AA, 30%(OWS); M:L Ratio, 1:5; [(KBrO3)/(TUDO)],
6/6 mmole/100g CMS; Time, 90 min.
TC
%
32
Effect of Acrylic Acid Concentration (% OWS) on TC% of Acrylic Acid
0
20
40
60
80
100
0 20 40 60 80 100Time (min.)
CMS, (DS= 0.199), (η= 70 mPa s); M:L Ratio, 1:5; [(KBrO3)/(TUDO)], 6/6 mmole/100g CMS;
Temp., 40oC.
TC
%
20% (OWS)30% (OWS)40% (OWS)60% (OWS)80%(OWS)
33
Effect of Acrylic Acid Concentration (% OWS) on TC% of Acrylic Acid
0
20
40
60
80
100
0 20 40 60 80 100AA% (OWS)
CMS, (DS= 0.199), (η= 70 mPa s); M:L Ratio, 1:5; [(KBrO3)/(TUDO)], 6/6 mmole/100g CMS;
Temp., 40oC; Time, 90 min.
TC
%
34
Effect of DS and Viscosity (mPa s) of CMS on TC% of Acrylic Acid
0
20
40
60
80
100
0 20 40 60 80 100Time (min.)
M:L Ratio, 1:5; [(KBrO3)/(TUDO)], 6/6 mmole/100g CMS; Temp., 40oC; AA, 30%
(OWS).
TC
%
DS ,Viscosity0.046, 134.20.044, 38.70.038, 10.50.191, 169.20.199, 700.211, 18.10.393, 198.30.388, 212.30.343, 31.5
35
Effect of DS and Viscosity (mPa s) of CMS on TC% of Acrylic Acid
0
20
40
60
80
100
0 0.1 0.2 0.3 0.4 0.5DS
M:L Ratio, 1:5; [(KBrO3)/(TUDO)], 6/6 mmole/100g CMS; Temp., 40oC; AA, 30%
(OWS); Time, 90 min.
TC
%
CMS from NS
CMS from HS
CMS from HHS
36
Optimum conditions: • Material: Liquor Ratio, 1:5
• Equimoleculare Ratio of KBrO3/TUDO, 6/6
mmole/100g CMS.
• Reaction Temperature, 40oC.
• Acrylic Acid, 30% (OWS).
• CMS prepared from HS with DS= 0.199 and
η=70 mPa s. • Reaction time, 90 min.
Chosen Sample Sample prepared by applying the optimum
conditions on CMS from NS [DS, 0.2; COOH
content, (115 mmole/100g CMS); η, (158 mPa s)] was
chosen for characterization.
37
Characterization
-COOH Content: It was found out that -COOH content due to grafting
is very little (87 mmole/100g CMS), less than COOH
content due to carboxymethylation (115 mmole/100g
CMS).
38
SEM CMS*-PAA
39
Thermal Analysis (DSC) CMS*-PAA
40
Advantages of the polymerization process
used:
• High viscosity of the composite.
• High adhesion of the composite.
• High Swelling in water of the dry composite or dry
graft copolymer.
• Water soluble composite.
Disadvantages of the polymerization process
used:
• Little graft yield.
• High homopolymer yield.
41
Conclusion
• The process could be recommended for providing a
water soluble starch composite.
• The process could not be not recommended for
providing a CMS-PAA graft copolymer.
Advice In case of having CMS-PAA graft copolymer with
high graft yield, other initiation system should be
used. (See Part III)
Applications: • Sizing agents in the paper and textile industries.
• Printing thickeners for pigment dispersions.
• Adhesives.
• Ion exchange materials.
42
Acknowledgments
• Egyptian Government for funding the research at
Leeds University.
• Egyptian Government for providing funds for
attendance at 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. A. Hebeish (NRC, TRD)
Prof. Dr. A. Waly (NRC, TRD)
Prof. Dr. M.H. ElRafie (NRC,TRD)
Prof. Dr. J.T. Guthrie (University of Leeds, Colour
Chemistry Dept.)
