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Development and characterization of compatible cellulose blend membranes using cellulose and other natural biopolymers using a novel solvent

systemBy

Eugene F. Douglass, MS, PhDDepartment of Chemistry

Nazarbayev University, Astana, Kazakhstan&

Richard Kotek, PhDTECS, College of Textiles

North Carolina State University, Raleigh, NC USA

June 28, 2010

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Objectives - Reviewing briefly the literature, and previous

work with this system. To summarize the recent work developing new fibers and membranes using our novel solvent system.

To show the development of biopolymer blend cellulose membranes, using previous work as a foundation.

To show the characterization of the membranes. To extend the preliminary goals of the research

into a new creative area, developing brand new materials that may have use in the membrane industry, and to characterize these new materials.

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Presented by

1 - Introduction

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Layer of material which serves as a selective barrier Barrier is between two or more phases Remains impermeable to specific particles, molecules or

substances Osmotic forces enable free flow of solvents Some components are allowed passage into permeate

stream Others are retained and remain in the retentate stream

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Cellulosic sources Cellulose most abundant naturally occurring

polymeric raw material – very cheap raw material Wood pulp, cotton, other plant fibers, or plant

waste

Figure 1- Molecular structure of cellulose.11

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ExamplesCellulosic fibers and membranes Natural cellulose fibers: cotton, linen, & flax Regenerated cellulose: rayon fiber and film, cellophane film Cellulose dissolved in a solvent: Lyocell fiber and film Cellulose derivatives: nitrocellulose, celluloid, cellulose acetate fibers and

films

Early solution methods – Regenerated cellulose: Cellulose xanthate is made, dissolved, then regenerate the cellulose chemically.

Viscose process Rayon Problems: dangerous solvent, toxicity of waste material

Recent solution methods – Dissolve cellulose in a solvent system Lyocell process – prime commercial process

Lyocell Problems: solvent instability issues, expensive

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Amine and counter ion dissolution

Zn+2 > Li+ > Ca+2 > Mg+2 > Ba+2 > Na+ > NH4+ > K+

SCN- > I- > PO4-3 > Br- > Cl- > NO3

- > SO4-2 > ClO3

-

Order of decreasing swelling of cellulose 2

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Figure 2 – Swollen cellulose – crystal structure

A) ac sin γ projection; B) ab projection 2

Amine and metal salt association Ionic interactions assisting dissolution

+< 20mol%

> 20mol%SCNK

+

NH2CH2CH2NH2

dissociation

association

EDA=

cell-OH

dissolutioncell-OH= cellulose

K+ SCN

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Figure 3 – Coordination of ED and KSCN in solution9 Frey

Presented by

2 - Development of cellulose blend membranes

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Previous work at North Carolina State UniversityHyun Lee12 – developed cellulose fibers from this optimized

solvent blend, and did some basic membrane investigation Possible porous membrane Severe yellowing upon aging

Problems: could not reproduce this structure using means described Used non-reproducible method of casting

Used tape layers on glass rods Draw down on glass plate, hard to remove

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Figure 4 – Porous cellulose membrane12

Development of new casting process for reproducibility

Reproducibility is required Casting table Uniform casting bar Cast on PET plastic film for ease of placing in coagulation

bath and removal of coagulated membranes Obtained casting table and bars from Byk-

Gardner Obtained casting PET film and drawdown panels

for sample membranes

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Objective: Dissolution of cellulose and other biopolymers (DP 450)

Simple setup for dissolution, paddle stirrer apparatus

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Figure 5 - 7% free flowing ED/KSCN cellulose (DP = 450) solution

Figure 6 – Dissolution apparatus

Microscopic views of dissolution

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Table 1 - Different swelling and dissolution mechanisms for cotton and wood fibers in NMMO – water mixtures at various water contents.3

Background of invention of new material

Cellulose and starch are polysaccharides Bond linkage of glucose units different Solvent for cellulose works, perhaps would work for starch. Discussion with Drs. Kotek, Venditti, and Pawlak: Can

starch make a membrane with this solvent system? No, could we do a blend??

Motivation Attempt blend with starch for membranes; success! Based on success with starch; chitosan, chitin and soy

protein were also tried. Both porous and nonporous membranes were obtained, this

section describes the development of cellulose blended with starch to form a useful membrane.

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Table 2 -Types of starches used – all are blends

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Starch Amylose (%) Amylopectin (%)

Corn Starch ~26 ~74High Amylose starch >50 <50Waxy Maize Starch <5% >95%

Figure 7 - Amylose Figure 8 - Amylopectin

Presented by

3 - Characterization of porous cellulose blend membranes with

Starch

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SEM characterization of blend membranescellulose and corn starch

Cross sections of 50/50 cellulose and corn starch blend

membranes

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Figure 9 – 500x cellulose / corn starch blend membrane

Figure 10 – 5000x cellulose / corn starch blend membrane

Cross-sections of 50/50 cellulose and high amylose starch blend membranes

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Figure 11 – 500x cellulose / high amylose starch blend membrane

Figure 12 – 5000x cellulose / high amylose starch blend membrane

Cellulose and high amylose starchIncompatible

Cellulose and waxy maize starch

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Figure 13 – 500x cellulose / waxy maize starch blend membrane

Figure 14 – 5000x cellulose / waxy maize starch blend membrane

Cross-sections of 50/50 cellulose and waxy maize starch blend membranes

1000 nm pore size

Compatible!

TGA analysis of cellulose membrane and 50/50 cellulose / waxy maize starch membrane

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Figure 15 - Cellulose membrane: onset 332º C, end 371º C, ash

level about 28% Figure 16: Cellulose / wm starch blend membrane: onset 272º C, end 324º C, ash level about 20%

100

3030

100

Mass %

20o C

20o C 710o C

710o C

Wide Angle X-ray Scattering of blend membranesCellulose II structure Amorphous

structure Peaks at 16,17 and 23 2θ Broad peak at 20-22 2θ

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Cellulose / Waxy Maize Starch membrane

Figure 17 – cellulose membrane Figure 18 – cellulose / waxy maize starch membrane

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Table 3 - Tensile property comparison of cellulose and cellulose blend membranes

AuthorsTensile modulus

(kgf/mm2)

Failure stress

(kgf/mm2)

Failure strain

(%)

Khare2 NMMO 163.1 ± 61 6.62 ± 1.9 6.5 ± 1.5

Douglass nonporous cellulose 166.5 ± 16 5.36 ± 0.7 26.2 ± 10.1

Douglass porous cellulose 33.0 ± 9.3 0.59 ± 0.17 3.9 ± 1.4

Cellulose – wm starch blend 51.0 ± 15.2 1.06 ± 0.4 10.0 ± 5.3

Presented by

4 - Cellulose and proteins blended in solution to make

membranes

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Development of cellulose / soy protein blend membranes

Based on success with Starches, we thought protein might work First attempt with Brim Soy Protein isolate, received from USDA labs on

NCSU campus Two protein types in the Brim blend Dissolves well in solvent blend

ADM soy materials received from NC Soy Council SAF soy protein Archon F soy protein concentrate Profam 974 soy protein isolate (comparable to Brim)

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Sample blend membranes made from each protein, to determine best quality membranes. Brim and Profam 974 made best quality

membranes These were used for main

characterization Determine ideal mass ratios of Soy protein

to cellulose using Profam 974 at 40, 30 and 20% by characterization of each mass percent membrane.

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5 – Characterization of cellulose / soy protein blend membranes

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SEM cross section micrographs of 50/50 cellulose – soy protein blends – Compatible!

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Figure 19 – 50/50 Cellulose/brim membrane, 5000x

Figure 20 – 50/50 Cellulose/Profam 974

membrane, 5000x

TGA Analysis - cellulose membrane compared to cellulose/brim soy protein blend

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Figure 21 - Cellulose membrane: Onset 332º C, end

371º C, ash about 28% Figure 22 - Cellulose / brim blend membrane: Onset 241º C, end

342º C, ash about 28%

Mass %

20o C

20o C

710o C

710o C

100 100

30 30

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Figure 23 - Cellulose membrane: Onset 332º C, end 371º C, ash

level about 28%Figure 24 - Cellulose / Profam 974 blend membrane: Onset 284º C, end 344º C, ash level

about 9%

Mass %

20o C

20o C 710o C

710o C

100 100

30 30

TGA Analysis - cellulose membrane compared to cellulose/Profam 974 soy protein blend

Table 4 - Summary of TGA results for soy protein / cellulose blend membranes

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Table 8 - Comparison of TGA results between membranesMaterials Start temperature (ºC)

Onset temperature(s) (ºC)

Char level @ 710º C (%)

Cellulose fiber 242 350 11Cellulose

membrane 257 332 28Profam 974 189 276 27

Brim soy protein 193, 285 235, 310 25

Cellulose / Profam 974

mixed185 290, 362 18

Cellulose / Profam 974 membrane

200 283 9

Cellulose / brim mixed 201, 280 234, 355 19Cellulose /

brim membrane

178 241 28

Wide Angle X-ray Scattering of Profam 974 blend membraneCellulose II Structure Amorphous Structure Peaks at 16,17 and 23 2θ Broad Peak at 20-22 2θ

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Figure 25 – Cellulose membrane Figure 26 – Cellulose / Profam 974 membrane

Wide Angle X-ray Scattering of Stretched Soy Protein blend membranes Amorphous Structure Amorphous Structure

Peaks at around 14 and 21 2θ Around 14 and 21 2θ

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Figure 27 – Cellulose / Brim blend

Figure 28 – Cellulose / Profam 974 blend

Notice Notice

Tensile Properties Summary

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Table 5 – Comparison of Tensile properties for soy blend membranesSamples Tensile modulus

(kgf/mm2)Failure stress

(kgf/mm2)Failure strain

(%)Thickness

(mm)

Cellulose membrane 75 ± 12 2.5 ± 1.2 36 ± 12 0.047 ± 0.015

Cellulose / brim

membrane157 ± 52 3.2 ± 1.6 27 ± 12 0.029 ± 0.003

Cellulose / Profam 974 membrane

200 ± 75 4.7 ± 1.2 16 ± 8.0 0.026 ± 0.001

Cell / PF 40% 220 ± 53 5.0 ± 2.0 29 ± 12 0.026 ± 0.001

Cell / PF 30% 204 ± 74 4.3 ± 2.3 27 ± 12 0.031 ± 0.005

Cell / PF 20% 195 ± 69 2.4 ± 1.8 20 ± 12 0.034 ± 0.003

Presented by

6 – Later work at NCSU

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Presented by (click to enter name)

• Made blend fibers from cellulose / waxy maize, and cellulose / soy protein blends.

• Cross-linked cellulose and cellulose blend membranes to prevent falling apart in long term water contact.

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Presented by

7 – Coming work at Nazarbayev University

Brief Discussion

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ConclusionsNew dissolution process development: Using a special solvent system of ED/KSCN in a

65/35 mass % ratio, functional porous and non-porous membranes were produced that have comparable physical properties to other methods of making cellulose membranes.

New material development: Using the same solvent system, starch was

blended with cellulose in the solution and cast to make functional porous blend membranes, that are stronger than the cellulose porous membranes developed earlier, and very water absorbent.

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Conclusions Using the same solvent system, soy protein was

blended with cellulose to make functional non-porous blend membranes, that are strong and even more water absorbent than the blend membrane with starch.

The casting and drying processes were optimized to deal with issues of shrinkage that causes wrinkling and variable film thicknesses

Other polysaccharides (chitosan and chitin), and protein (keratin from hair) were also used to make functional blend membranes with cellulose, suggesting further applications for this system.

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Presented by

8 - References

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1. Ott . Cellulose and cellulose derivatives : Molecular characterization and its application. Burlington: Elsevier; 1954.

2. Khare VP, Greenberg AR, Kelley SS, Pilath H, Roh IJ, Tyber J. Synthesis and characterization of dense and porous cellulose films. J Appl Polym Sci 2007;105(3):1228-36.

3. Cuissinat C, Navard P. Swelling and dissolution of cellulose part 1: Free floating cotton and wood fibres in N-methylmorpholine-N-oxide-water mixtures. Macromolecular Symposia 2006;244(1):1.

4. Cuissinat C, Navard P. Swelling and dissolution of cellulose part II: Free floating cotton and wood fibres in NaOH-water-additives systems. Macromolecular Symposia 2006;244(1):19.

5. Fink H, Weigel P, Purz HJ, Ganster J. Structure formation of regenerated cellulose materials from NMMO-solutions. Progress in Polymer Science 2001 11;26(9):1473-524.

6. Swatloski RP, Spear SK, Holbrey JD, Rogers RD. Dissolution of cellulose with ionic liquids. J Am Chem Soc 2002;124(18):4974-5.

7. Zhang . 1-allyl-3-methylimidazolium chloride room temperature ionic liquid: A new and powerful non-derivatizing solvent for cellulose. Macromolecules 2005;38(20):8272.

8. Hafez MM, Pauls HW, inventors. Method for preparing thin regenerated cellulose membranes of high flux and selectivity for organic liquids separations. Exxon Research and Engineering Co., editor. 4496456. 1985 1/29/1985

9. Frey M, Li L, Xiao M, Gould T. Dissolution of cellulose in ethylene diamine/salt solvent systems. Cellulose 2006 04/29;13(2):147-55.

10. Cao Y. Preparation and properties of microporous cellulose membranes from novel cellulose/aqueous sodium hydroxide solutions. Journal of Applied Polymer Science [Internet]. [revised 2006;102(1):920.

11. Metzger J. Carbohydrate structures http://chemistry.gcsu.edu/~metzker/Common/Structures/Carbohydrates/

12. Lee HJ. Novel cellulose solvent system and dry jet wet spinning of Cellulose/ED/KSCN solutions. Raleigh, NC: North Carolina State University; 2007. Available from: unrestricted

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9- Acknowledgements North Carolina State University, College of Textiles

including Drs. Richard Kotek, Peter Hauser and Alan Tonelli Dr. Richard Venditti and Dr. Joel Pawlak, College of

Natural Resources Chuck Mooney, Birgit Anderson and Theresa White

Nazarbayev University, Astana, Kazakhstan seed funding to disseminate this work, and develop further work Drs. Kenneth Alibek SST, Sergey Mikhalovsky College of

Engineering

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