CELLULOSE/POLYSULFONE NANOCOMPOSITES. Graduate Student: Sweda Noorani. Advisors: Dr John Simonsen Dr Sundar Atre

Transcription

1 CELLULOSE/POLYSULFONE NANOCOMPOSITES Graduate Student: Sweda Noorani Advisors: Dr John Simonsen Dr Sundar Atre OSU Oregon State University Corvallis,Oregon

2 INTRODUCTION CONTENTS EXPERIMENTAL METHODS RESULTS CONCLUSIONS ACKNOWLEDGMENTS

3 INTRODUCTION

4 MECS Microtechnology for energy and chemical systems

5 Materials & Process Design for MECS Prof. Sundar V. Atre material polymer metal ceramic composite process injection molding extrusion sintering micromachining application kidney dialysis microreactor thermal management fuel cell

6 Microchannel Reactors - Steam Reforming Designed for efficient steam reforming Current system: CO and H 2 for 10 kwe fuel cell system

7 Components - Fractal Desorber Fractal geometry minimizes pressure drop and flux uniformity Applied to heat exchangers, desorbers, mixers and chemical reactors

8 Microchannel Separations - Portable Kidney Dialysis with HD+ Technology and Treatment Enhancement Through MECS technology and Meso-Scale Manufacturing HD+ will be able to reduce the size of the dialyzer and increase the clearance efficiency over the current fiber based dialyzer modules 90%CE versus 35%CE). HD+ has signed an exclusive options agreement with OSU for specific MECS technology and manufacturing processes.

9 Camera Visual Access Blood Adjustable Spacer Quartz Window Membrane Dialysate Prof. Goran Jovanovic, OSU ChE

10 Prototype Note that impact will be similar in many separation processes

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13 Dialyzers old vs. new MECS dialysis ultrafilter Hollow Fibers Polysulfone High Flux/Good Specificity Mechanically flexible Hollow fiber filter Membrane not optimized for microchannel devices

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15 Microchannel Devices Advantages Smaller size. Lower cost. Dialysis operation can be performed easily. Improved patient treatment. Microchannel membranes should be STIFF and FLAT

16 Objectives To incorporate cellulose nanocrystals(cnxls) in a polysulfone (PSf) matrix to produce CNXL/PSf nanocomposites. To investigate the properties of these nanocomposites.

17 EXPERIMENTAL METHODS

18 Cellulose Nanocrystal Production Native cellulose - Semi crystalline Polymer (~70% crystalline). Crystalline portion Amorphous portion CONTROLLED ACID HYDROLYSIS

19 TEM image of CNXL L d L/d=Aspect ratio Diameter=5-20nm Length= nm Aspect ratio=10-70 Agglomeration Single strand

20 Percolation threshold ~ 1.5% Aspect ratio = 50 Garboczi, et. al. Phys. Rev. Ltrs. E, 1995, 52(1):

21 Material Mechanical properties cellulose crystal Aluminum E-glass Steel (high tensile) Graphite Carbon nanotubes** Strength,MPa Stiffness,GPa 145* Comparison of mechanical properties of various materials (Jones,1975) *Eichhorn, et al. Biomacromol. 2005, 6: 507 **Yu, et al. Science 2000, 287: 637

22 Polysulfone isopropylidene ether diphenylene sulfone Excellent Thermal Stability Low creep Transparent Rigidity Maintains its electrical and physical properties over a wide range of temperature

23 Polymer Film Preparation CNXL transferred from water to 1-1 methyl-2-pyrrolidone (NMP) by Solvent Exchange Process. Polysulfone (PSf) dissolved in CNXL dispersed NMP. Films made by phase inversion.

24 Solvent exchange Mix aqueous dispersion of CNXLs with NMP. Rotovap (remove water). Sonicate to break up any agglomerates. Result = dispersion of CNXLs in NMP. Add PSf powder or pellets, stir to dissolve. Result = CNXL dispersion in PSf/NMP solution.

25 Phase immersion Conventional process for manufacture of ultrafiltration membranes, including hemodialysis membranes. Polymer solution/dispersion film substrate (glass sheet) Substrate (glass sheet) water bath

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27 Mechanical testing Sintech 1G, Universal testing machine Tensile test mode Data converted to stress-strain strain curves Modulus reported is the initial linear portion of the stress- strain curve Evaluation

28 Evaluation Thermogravimetric analysis TA Instruments Q500 Temperature range o C Heating rate 10 o C/min

29 Scanning electron microscopy (SEM) Evaluation AMRay 10 kv Coated with Au-Pd film (8-10 nm)

30 Evaluation Atomic force microscopy (AFM) DI Dimension 3100 (Veeco Instruments) Tapping mode

31 Water Vapor transmission rate Controlled Environment Chamber Temperature=30 o C Relative humidity = 90% Covered at the ends to prevent loss of water water D

32 Water vapor transmission rate wt loss (g) WVTR Time (dy) Slope of graph= wt loss/time. Area= area through which WVTR takes place. Flux = slope of graph/area Flux=(g/m^2-dy).

33 RESULTS

34 3 Mechanical Properties 2.5 Tensile modulus, GPa Theoretical percolation threshold agglomeration CNXL, wt %

35 Water vapor transport rate Flux (g/m 2 dy) % Cellulose nanocrystals

36 Thermogravimetric Analysis dw/dt (%/degc) CNXL 0% 2% 11% Temperature ( 0 C)

37 Morphology

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41 0% CNXL

42 2% CNXL

43 11% CNXL

44 16% CNXL

45 Conclusions CNXLs can be incorporated into PSf by a novel solvent exchange process. Nanocomposite films can be obtained. Microscopic observations revealed that CNXLs were well dispersed at lower filler loadings. TGA curves revealed interaction between PSf/CNXL at lower filler loadings and poor interaction at higher filler loadings.

46 Conclusions Modulus and WVTR show a percolation threshold at ~1% filler loading. Modulus and WVTR approximately triple due to presence of CNXLs at low filler loadings (~2 5%). Modulus decreases at filler loadings >7% presumably due to agglomeration. Highly variable results of WVTR at filler loadings >7% maybe due to agglomeration.

47 ACKNOWLEDGEMENTS This project was supported by the National Research Initiative of the USDA Cooperative State Research, Education and Extension Service, grant number

48 Questions