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Modification of Cassava Starch As Filler For Polypropylene Compound

Department of Chemical Engineering, Faculty of EngineerKing Mongkut’s University of Technology North Bangkok

Nuchanart Charoennit

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Contents

Background Objective Experimental Result and discussion Conclusion

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Cassava Starch

(C6H10O5)n

Cassava starch

Starch Contents 85.00% Moisture 13% pH 5 – 7 Ash 0.20% Viscosity 600 B.U. SO2 30 ppm. Colour White

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Polypropylene

High melting point

Good stiffness

Low specific gravity

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Admicellar Polymerization

Water

Admicelle Formation

PolymerizationAdsolubilization Washing

StarchStarch Starch Starch

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Adsorption Isotherm

Log equilibrium surfactant concentration (mole/L)

Log

surf

acta

nt a

dsor

ptio

n (m

ole/

g)

Period 1 Period 2 Period 3 Period 4

Micelles

Admicelle

CMC

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Admicelle formation

Admicelle formation

Adsolubilization Polymerization Washing

Starch Surface

SurfactantSurfactant

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Adsolubilization

MonomerMonomer

Admicelleformation

Adsolubilization Polymerization Washing

Starch Surface

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Polymerization

Adsolubilization Polymerization WashingAdmicelleformation

Starch Surface

Polymer film

Polymer film

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Washing

Polymer filmPolymer film

Adsolubilization Polymerization WashingAdmicelle formation

Starch Surface

Objective

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Poor Compatibility

Admicellar Polymerization

ImproveCompatibility

Starch

Polypropylene

Improve mechanical properties

Modified starch

Experimental

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Cassava starch

Starch/PP blends

Compression Molding

Mechanical Testing

Tensile ImpactFlexural Moisture Absorption

Biodegradable

Cassava starch

Modified starch

Admicellar Polymerization

Characterization

PP

PP

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Material

Chemical

Raw Material • Cassava starch powder• Polypropylene (EL-PRO P600F)

Surfactant Cetyl-trimethyl ammonium bromide (C16H33)N(CH3)3Br)

Monomer Isoprene (C5H8)

Initiator Ammonium persulfate (NH4)2S2O8

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Admicellar Polymerization

Surfactant Solution

CTAB

Deionized Water

CTAB Solution

(NH4)2S2O8

Admicellar Polymerization (Cont.)

CTAB Solution

Ethanol

K2S2O8

Isoprene

24 hr. 24 hr. 2 hr.

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Starch

Admicelle Formation PolymerizationAdsolubilization

Admicellar Polymerization (Cont.)

1 hr.

80ºC

24 hr.

H2O

Modified Starch

16Polymerization Washing

Preparation of starch/PP blends

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Unmodified starch

Two-rolls mill

Modified starch Preheat 5 min.

PP Compression molding

Set at 180C

Compress for 5 min.

Cool down

at 180C

Starch (%) PP (%)

0 1005 95

10 9015 8520 8025 7530 70

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Characterization

Zeta Potential

Morphology

Film Formation

Zeta potential analyzer

SEM

FT-IR

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-40.0

-35.0

-30.0

-25.0

-20.0

-15.0

-10.0

-5.0

0.0

5.05.2

-0.7

-9.0

-17.2

-33.7

-25.7

-27.9

-34.4

-24.4

-38.9pH

Zeta

Pot

entia

l (m

V) Point of Zero Charge at [pH = 1.4]

1 2 3 4 5 6 7 8 9 10

Zeta Potential

Figure 1. Zeta potential of starch as function of pH

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FT-IR

Figure 2. FT-IR spectra of unmodified starch and modified starch

4000 3500 3000 2500 2000 1500 1000 500

CH2 bending (1470)

CH2 -CH2 stretching (2700-2900)

-OH (3430)

C=C(1600)

Modified starch

Unmodified starch

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Morphology

Figure 3. SEM of (a) unmodified starch and (b) modified starch

(b) Modified starch(a) Unmodified starch

Mechanical Testing

Tensile strength

Impact strength

Flexural strength

Universal testing machine ASTM D638

Resil ImpactorASTM D638

Universal testing machine ASTM D638

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Moisture absorption

Biodegradable

% Moisture absorption

% Weight loss

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Tensile strength

0 5 10 15 20 25 305.00

10.00

15.00

20.00

25.00

30.00

35.00 unmodified starch/PPmodified starch/PP

Starch content (%)

Tens

ile s

tren

gth

(MPa

)

Figure 4. Tensile strength of starch/PP blends

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Flexural strength

Figure 5. Flexural strength of starch/PP blends

0 5 10 15 20 25 3020.00

25.00

30.00

35.00

40.00

45.00 unmodified starch/PPmodified starch/PP

Starch content (%)

Fle

xura

l S

tren

gth

(M

Pa)

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Impact strength

0 5 10 15 20 25 305.00

10.00

15.00

20.00

25.00

30.00

35.00 unmodified starch/PPmodified starch/PP

Starch content (%)

Tens

ile s

tren

gth

(MPa

)

Figure 6. Impact strength of starch/PP blends

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Moisture Absorption

Figure 7. Moisture absorption of starch/PP blends

0 5 10 15 20 25 300.00

0.50

1.00

1.50

2.00

2.50

3.00 unmodified starch/PPmodified starch/PP

Starch content (%)

% M

oist

ure

abso

rptio

n

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Biodegradable

Figure 8. % weight loss of starch/PP blends

0 5 10 15 20 25 300.00

0.50

1.00

1.50

2.00

2.50

3.00 unmodified starch/PPmodified starch/PP

Starch content (%)

%W

eigh

t los

s

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Conclusion

The formation of polyisoprene film on starch surface by admicellar polymerization was successfully and polyisoprene film was confirmed by FTIR analysis.

The mechanical properties including tensile, flexural properties and impact strength of modified starch/PP compound were better than those of the unmodified starch/PP compound.

% Moisture absorption of modified starch/PP was significantly less than unmodified starch/PP while the biodegradability was slightly lower than that of unmodified starch/PP compound.

LOGO

Non-ionicAmphoteric

_+

Anionic

_

Hydrophilic Hydrophobic

Surfactant

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Surfactant

Cationic

_

In this work the room temperature initiator needed.

Conditions: Heat and excess water Dissolve in solvent;

alkali, DMSO, aq. CaCl2

Gelatinization

Heat

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Starch source Temp. (C)

Corn 70-89

Potato 57-87

Wheat 50-86Cassava 68-92

Gelatinization

Native Granules Swollen Granules

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Initiator

Properties

Molecular formula (NH4)2S2O8

Molar mass 228.18 g/mol

Appearance Solid white crystals

Density 1.98 g/cm3

Melting point120 °C (393 K)

decomp.

Solubility in water 80 g/100 ml (25°C)

pH 2-3 (250 g/l) (20°C)

Ammonium persulfate is a strong oxidizing agent.use : Initiator for polymerizations, oxidizing agent

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Adsorption isoterm of CTAB

500 5000 500001

10

100

1000

10000

Log Equlibrium concentration (M)

Lo

g A

ds

orp

tio

n c

on

ce

ntr

a-

tio

n (

m

ol/

g) CMC

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MS & Bio

Bio

%weight loss

W1 = Initial weightW2 = final weight

MS

%moisture absorption

M1 = Initial weightM2 = final weight

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Appearences of starch/PP blends

5% modified starch0% modified starch

15% modified starch10% modified starch

25% modified starch

30% modified starch

20% modified starch