Development and characterization of compatible cellulose and cellulose blended with soy protein membranes using a novel solvent system By Eugene F. Douglass, MS, PhD Department of Chemistry Nazarbayev University, Astana, Kazakhstan & Richard Kotek, PhD TECS, College of Textiles North Carolina State University, Raleigh, NC USA June 28, 2010 1

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. 2

1 - Introduction 5

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 6

Figure 1- Molecular structure of cellulose.11 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 7

Examples 8 Cellulosic 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 8

Amine and counter ion dissolution ac sin γ projection; ab projection 2 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 Figure 2 – Swollen cellulose – crystal structure 9

Amine and metal salt association Ionic interactions assisting dissolution Figure 3 – Coordination of ED and KSCN in solution9 Frey 10

2 - Development of cellulose blend membranes 11

Previous work at North Carolina State University Hyun 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 Figure 4 – Porous cellulose membrane12 12

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 13

Simple setup for dissolution, paddle stirrer apparatus Objective: Dissolution of cellulose and starch or protein as a blend50) Simple setup for dissolution, paddle stirrer apparatus Figure 5 - 7% free flowing ED/KSCN cellulose (DP = 450) solution Figure 6 – Dissolution apparatus 14

Microscopic views of dissolution Table 1 - Different swelling and dissolution mechanisms for cotton and wood fibers in NMMO – water mixtures at various water contents.3 15

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 soy protein to form a useful membrane. 34

Table 2 -Types of proteins used Optimum Percent Brim Soy Protein (USDA) ~50 Profam 974 Isolate 40-50% 35

3 - Cellulose and proteins blended in solution to make membranes 47

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) 48

Brim and Profam 974 made best quality membranes 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. 49

4 – Characterization of cellulose / soy protein blend membranes 50

SEM cross section micrographs of 50/50 cellulose – soy protein blends – Compatible! Figure 7 – 50/50 Cellulose/brim membrane, 5000x Figure 8 – 50/50 Cellulose/Profam 974 membrane, 5000x 51

Figure 9 - Cellulose membrane: Onset 332º C, end 371º C, ash about 28% TGA Analysis - cellulose membrane compared to cellulose/brim soy protein blend 100 100 Mass % 30 Figure 9 - Cellulose membrane: Onset 332º C, end 371º C, ash about 28% 30 20o C 710o C Figure 10 - Cellulose / brim blend membrane: Onset 241º C, end 342º C, ash about 28% 20o C 710o C 52

TGA Analysis - cellulose membrane compared to cellulose/Profam 974 soy protein blend 100 100 Mass % 30 30 Figure 11 - Cellulose membrane: Onset 332º C, end 371º C, ash level about 28% 20o C 710o C Figure 12 - Cellulose / Profam 974 blend membrane: Onset 284º C, end 344º C, ash level about 9% 20o C 710o C 53

Table 8 - Comparison of TGA results between membranes Table 3 - Summary of TGA results for soy protein / cellulose blend membranes Materials Start temperature (ºC) Onset temperature(s) (ºC) Char level @ 710º C (%) Cellulose fiber 242 350 11 Cellulose membrane 257 332 28 Profam 974 189 276 27 Brim soy protein 193, 285 235, 310 25 Cellulose / Profam 974 mixed 185 290, 362 18 Cellulose / Profam 974 membrane 200 283 9 Cellulose / brim mixed 201, 280 234, 355 19 Cellulose / brim membrane 178 241 Table 8 - Comparison of TGA results between membranes 54

Wide Angle X-ray Scattering of Profam 974 blend membrane Cellulose II Structure Amorphous Structure Peaks at 16,17 and 23 2θ Broad Peak at 20-22 2θ Figure 13 – Cellulose membrane Figure 14 – Cellulose / Profam 974 membrane 55

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 Notice Notice Figure 15 – Cellulose / Brim blend Figure 16 – Cellulose / Profam 974 blend 56

Tensile Properties Summary Table 4 – Comparison of Tensile properties for soy blend membranes Samples 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 membrane 157 ± 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 Cell / PF 30% 204 ± 74 4.3 ± 2.3 0.031 ± 0.005 Cell / PF 20% 195 ± 69 2.4 ± 1.8 20 ± 12 0.034 ± 0.003 57

Physical Properties Summary Table 5 – Comparison of water absorbency for soy blend membranes 57

5 – Later work at NCSU 59

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. 60

6 – Coming work at Nazarbayev University Brief Discussion 61

Conclusions New 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, soy protein was blended with cellulose in the solution and cast to make functional non-porous blend membranes, that are stronger than the cellulose porous membranes developed earlier, and very water absorbent. 62

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, perhaps using wool will give some interesting materials, both as membranes and fibers. 63

7 - References 64

Ott . Cellulose and cellulose derivatives : Molecular characterization and its application. Burlington: Elsevier; 1954. 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. 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. 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. 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. Swatloski RP, Spear SK, Holbrey JD, Rogers RD. Dissolution of cellulose with ionic liquids. J Am Chem Soc 2002;124(18):4974-5. Zhang . 1-allyl-3-methylimidazolium chloride room temperature ionic liquid: A new and powerful non-derivatizing solvent for cellulose. Macromolecules 2005;38(20):8272. 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 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. 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. Metzger J. Carbohydrate structures http://chemistry.gcsu.edu/~metzker/Common/Structures/Carbohydrates/ 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 65

8- 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 66