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Morphology & Functionalization: Processing & Characterization R. A. Weiss

Morphology & Functionalization: Processing & Characterization R. A. Weiss M. Cakmak , S. Gupta, E. McClanahan, J. Marszalek The University of Akron ONR Capacitor Materials Program Review. March 7, 2012. 1. OBJECTIVE. Motivation

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Morphology & Functionalization: Processing & Characterization R. A. Weiss

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  1. Morphology & Functionalization: Processing & Characterization R. A. Weiss M. Cakmak, S. Gupta, E. McClanahan, J. Marszalek The University of Akron ONR Capacitor Materials Program Review March 7, 2012 1

  2. OBJECTIVE • Motivation • To identify/develop high dielectric constant, low loss, high breakdown strength high temperature polymers • To understand the relationship between morphology and breakdown strength in biaxially-oriented PP • Objectives • Synthesize polar-functional polymers from high temperature polymers • Characterize structure and properties of polymers synthesized in the other MURI labs – Chung (PSU) and Sotzing (UConn). • Manufacture polymer films for capacitance and breakdown testing (for UA, PSU, UConn) • Prepare well-characterized biaxially-oriented PP samples for breakdown studies (for Boggs (UConn)) 2

  3. TECHNICAL APPROACH: POLYMER MODIFICATION Quantum Mechanical Computations by Rampi PP-OH PP Rampi Conclusions (Nov 3, 2010 Webex Mtg.) “ –OH functionalization displays the highest polarizability per volume” “ –NO2, –SH, –SO3H also ‘pass’ screening and are recommended” 3

  4. TECHNICAL APPROACH: POLYMER MODIFICATION Sulfonated Poly(ether ether ketone) Rampi PEEK PP Shibuya, Porter, Macromolecules, 25, 6495 (1992) 4

  5. TECHNICAL APPROACH: CHARACTERIZE PP-OH Mike Chung • X-Ray Diffraction • Small Angle X-Ray Scattering • Thermal Gravimetric Analysis • Differential Scanning Calorimetry • Dynamic Mechanical Analysis • Oscillatory-Shear Rheology • Steady-Shear Rheology

  6. TECHNICAL APPROACH: MANUFACTURE FILMS National Polymer Innovation Center Wright Center of Innovation in Polymer Engineering Miko Cakmak, Director SPEEK and PP-OH solutions

  7. Intensity (a.u.) 10 15 20 25 30 35 40 45 50 2θ (deg) ACCOMPLISHMENTS PP-OH PP and PP-OH have monoclinic crystal structures – no effect of OH substitution 7

  8. Lamellar Thickness of PP-OH Crystals Small Angle X-Ray Scattering) Polypropylene d = 15.0 nm PP-OH (3.93% OH) d = 12.3 nm Iq2 (a.u.) PP-1 PP-2 PP-OH (1.3) PP-OH (1.4) PP-OH (1.7) PP-OH (3.9) 0 0.25 0.5 0.75 1.0 1.25 1.5 1.75 2.0 q (nm-1) Spherulite (space-filling) Growth Direction d Chain Direction lamella thickness (long spacing) Scattering Invariant

  9. Dynamic Mechanical Analysis of PP-OH ) MPa Glassy modulus Rubbery modulus Modulus ( H-bonding crystallinity [OH] mol% Glass transition Glassy region Rubbery flow Melt transition Melt flow f = 1 Hz heating rate =2 C/min SAOS measurement

  10. Melt Rheology (Dynamic Experiments) aTw (1/s) aTw (1/s) • TTS works well • With increasing [OH], the melt viscosity increases and the melt becomes more elastic (that together with the lower crystallinity should make the PP-OH easier to biaxially orient than PP)

  11. Melt Rheology of PP-OH Samples 105 104 103 102 101 100 τ ~ 0.01 s τ ~ 0.3 s PP (Mv = 511 kg/mol) G” η’0.1 ~ 103 Pa.s G’ 106 105 104 103 102 bTG’ or bTG” (Pa) PP-OH (1.7 mol% OH) (Mv = 388 kg/mol) ?? 2 2 G” 1 1 G’ η’0.1 ~ 2 x 104 Pa.s 10-2 10-1 100 101 102 103 aTω (s-1) Viscoelastic Mastercurves @ 200C

  12. Anomalous Behavior for PP-OH (3.9 mol% OH) Sanat Kumar Simulations of PE-OH indicate aggregation of -OH Weak Elastic Network No viscous flow bTG’ or bTG” (Pa) 2 1 aTω (s-1)

  13. . h = h0 [1+(lg)2](n-1)/2 Carreau Model Steady-Shear Rheology Zero-shear viscosity (ho) Increasing –OH increases zero-shear rate viscosity and non-linear viscosity

  14. Steady-Shear Rheology network? increasing -OH Increasing –OH increases the shear-thinning behavior. increasing -OH Increasing –OH increases the melt elasticity.

  15. Sulfonated PEEK (SPEEK) Thermal Properties of S-PEEK

  16. Dielectric Properties of SPEEK

  17. PE-BIAXIAL STRETCHER Polymer Film PP Film Processing and Biaxial Orientation Roll Stack (x 3) Extruder die Melt-Cast Film 235 mm (9.25”) 250-300 mm

  18. ISSUES • PP-OH Film Processing • Melt casting: requires more material than available • Solvent casting: need to add temperature control of feed to film line • Biaxial Stretching: need better control of thickness of precursor films • SPEEK • Solvent removal • Film Processing (General) • Biaxial Stretching requires very uniform samples • Melt casting requires large quantities of material • Compression molding requires precision tool that is currently not available 18

  19. CONCLUSIONS • Staff and procedures are in place for thorough characterization of materials prepared in the different MURI labs • Chung PP-OH has been fully characterized • Crystal Structure unaffected • Crystallinity and crystal size decrease • Viscosity and elasticity increase  may be easier to biaxially stretch • SPEEK can and has been sulfonated over a wide range of substitution values • increases Tg, decreases Tm and decreases/eliminates crystallinity • increases e and loss, but loss is less for metal salt than for the acid  may be an opportunity to mediate changes using different Coulombic energies • Melt casting fabrication of PP film has been demonstrated with our equipment • Solution casting fabrication of SPEEK film has been demonstrated 19

  20. CURRENT AND FUTURE WORK • Retrofit film-casting equipment with temperature control of feed • Obtain a precision compression mold for Biaxial Orientation specimens • Prepare M-SPEEK samples and films of with different cations and relate dielectric properties to microstructure and Coulombic energy of the ion-pair • Continue to characterize PP-x samples from Mike Chung (PSU) and polymers from Greg Sotzing (UConn) • Work with Sanat Kumar (Columbia) to model nanophase separation and rheology of polar-functionalized polymers • Collaborate with Dow Corning on novel siloxane polymers 20

  21. RECENT PUBLICATIONS, PATENTS, AWARDS • No publications yet. • Draft of a paper with Mike Chung (PSU) regarding structure and rheological behavior of PP-OH is underway. Anticipate submission in April. 21

  22. NAVY RELEVANCE and IMPACT • Capacitor Materials Program Relevance • Gaining an understanding of how functionalization affects microstructure and rheology of polymers  How do these affect dielectric properties of the polymer and ability to make film. • Developing knowledge base on how to process PP and non-PP polymer capacitor film. • Broader Impact • SPEEK and SPEKK are candidates for Membranes in PEM Fuel Cells and Redox Flow Batteries. (Proposals have been submitted to NSF and Ohio Third Frontier (with Ashlawn Energy, LLC) • SPEEK also seems to make a viable high temperature shape-memory polymer. (some seed funding from NASA) 22

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