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Dynamic Mechanical Analyzer EC-Twist

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  1. Dynamic Mechanical Analyzer EC-Twist

  2. Rheology RoadRheology describes the flow and deformation behaviour

  3. Polymer Characterization3 Groups Poly(many)Mer(many) 103 – 106 • Thermo-Melts • Linear or branched • Start melting above melting temperature • Elastomers • Sparsely linked • Do not melt at higher temperatures • Thermo-Sets • Densely linked • 2K adhesives, epoxy resin based materials • Do not melt at higher temperatures • Mechanical properties almost independent from temperature

  4. EC-TwistDynamic Mechanical Analyzer Material characterization Melts DMTA Sealants, Adhesives Mechanical properties Curing Elastomers Time, temperature, frequency http://www.anton-paar.com/DE/de/Web/Document/download/11158?clng=en

  5. EC-TwistMelt rheology in tensile mode MELT RHEOLOGY Extensional viscosity STEP RATE TEST Extensional viscosity Branching UXF, SER

  6. Extensional viscosityMeasurements with UXF or SER • Setting: constant tensile rate Setting Zeit t Measurement until strain hardening or melt fracture slope is a qualitative measure for the degree of cross linkage or branching of polymer melts or elastomers 0.1s-1 1.0s-1 Extensional viscosity hE time t

  7. EC-TwistMelt rheology in shear mode MELT RHEOLOGY Shear-rheology PP25 (PP35), CP25-3/TG (CP35-3/TG) • FLOW CURVE, FREQUENCY SWEEP • Zero shear viscosity • Relaxation time • Power law exponent • Deborah number • Master Curve • Mw, MMD (relative) . g

  8. Viscosity Curve Orientation and relaxation • Shear thinning due to orientation, which results in lower viscosities • Polymer melts or highly concentrated solutions . entangled g h time relaxation orientationshear disentangled

  9. Viscosity Curve, CompositesFinding structures... • Lower shear rates: more sensitive to interacting forces • High shear rates: orientation of structures High concentration of filler . g h Low concentration of filler

  10. Viscosity Curve, CompositesFinding structures... • By regression the viscosity for any concentration can be found -> can be done by copying viscosity values into Excel Particle-Particle interactions -> Friction due to high concentration h Particles are “free” to move within the matrix liquid cv 5% 20% 10% Solid-volume concentration Cv [%]

  11. Viscosity Curve – Carreau-Yasuda RegressionWhat‘s the meaning of the 3 ranges? Zero shear viscosity = proportional to molar mass n Power law exponent = qualitative measure for the macro molecules to orient in shear direction und to reduce flow resistance a Width of transition range = proportional to MMD and PDI-> narrow MMD=steep, broad MMD=flat) l Relaxation time = time dependent recovery of internal stresses De Deborah Number h* Rule of thumb for processing Make sure that De value is as low as possible w

  12. Solving Processing IssuesToo much elasticity and relaxation issues Unwanted side effects due to long relaxation times and high shear processing speeds • Die swell • after leaving the nozzle • Melt fracture • limited processing speed • Sharkskin • often found with LLDPE and HDPE • Strategy: • Processing additives (e.g. PPA) => reduced risk of melt fracture during extrusion • Modification of MMD => lower storage modulus G‘ at higher frequencies (shifted cross over towards higher frequencies) or lower N1 at higher shear rates • Deborah-Number De = processing shear rate (smallest diameter) * relaxation time

  13. Frequency SweepVisco-elastic liquid (no gel, unlinked, no filler) • Long term: newtonian behaviour • Short term: viscoelastic behaviour • No network structure • No links between macro-molecules Complex viscosity G‘‘ G‘ 1 2 1 1 Angular frequency w

  14. Frequency SweepVisco-elastic, partially linked • No long term relaxation • Gel stability due to 3D-network structure G‘ • Slope: • Strength of structure at rest • Absolute value: • Stiffness of gel • Damping G‘‘/G‘ • Damping behaviour G‘‘ Complex viscosity Angular frequency w

  15. 10.000 100.000 Pa 10.000 t Pa·s 1.000 h N 1 100 1.000 10 0,01 0,1 1 1/s 10 . Scherrate g Flow Curve with N1 (Polycarbonate)1. Normal Stress Difference N1 causes flow phenomena • 1st normal stress difference • causing: melt fracture and die swell effects • edge effects at higher shear rates-> therefore only limited chance to measure these samples ! • NOTE: If N1 > t, then measuring data is no longer stable

  16. Frequency Sweep – Master CurveTime Temperature Superposition • Background: • Due to increasing T the relaxation times are getting shorter • Shift factor aT=l(T)/l(Tref) or based on viscosity aT=h(T)/h(Tref) • Frequency sweeps (FS) measured at various T can be shifted horizontally • Only applicable for unlinked and unfilled polymers • Each FS measured at T can be shifted by aT to the so called reference temperature T0 (+) Enlarged frequency range (+) Information about practically relevant shear rates up to 100.000s-1 (+) Determination of the zero shear viscosity

  17. Frequency Sweep – Master CurveHorizontal shift towards the reference temperature T0 • TTS example: horizontal shift of storage modulus G‘ Storage modulus G‘ 160°C 180°C 200°C 230°C 260°C Angular frequency w

  18. Frequency Sweep – Master CurveHorizontal shift towards the reference temperature T0 • TTS example: shift of storage modulus G‘ • The range abover the transition region is called glassy region

  19. Frequency Sweep – Master CurveWorkbook assistant and loop temperature • The FS is executed 1x for each of the Loop-T defined in the list: • The first Loop-T in the list must be the reference temperature T0 • Temperature in the “Start Dialog” is automatically replaced by the next T from the list • A macro ‘@consttemp@ in the data series name ensures that the Loop-T is part of thedata series name • Optimized settings for CTD or ETD ensure perfect temperature equilibration e.g. T0=190°C

  20. Frequency Sweep – Master CurveSpecific settings of the analysis method • Shift is done automatically • Target temperature is entered which is equal to the reference T0 • In the case of any issue with auto calculation the parameters must be defined manually • The following settings may solve the issues with unsteady or badly overlapping measuring data: • Range = valid range of deviation (will stop analysis if exceeded for a single point of the shifted curve • Shift horizontal OR hirizontal and vertical (vertical = correction of density) • Scattering at lower frequencies -> increase value for lower points • Scattering at higher frequencies -> increase value for higher points • The reduced range is only used for shifting the curves; all points are included in the resulting master curve at T0

  21. Frequency Sweep – Master CurveFurther analysis – Activation Energy • WLF (amorphous polymers T>/=Tg) and Arrhenius (partially crystalline polymers T>>Tg) allowing a regression of • shift factors against temperature • calculated activation energy E0 = 12,831 kJ/mol • Gas constant RG = 8.314*10-3 kJ/(mol*K) • E0 is calculated from E0 = RG * b • Flow activation energy describes E0 the amount of energy needed to move the molecules at a certain temperature T0 • Based on WLF or Arrhenius regression a FS at any temperature of the curve can be calculated

  22. EC-TwistDMTA in torsion and extension DMTA Torsion DMTA TORSION & EXTENSION DMTA Tension Trange, 1Hz g = 0.01-0.1% G‘, G‘‘, tan(d) Size: 40mm, 1mm-2mm, 10mm SRF UXF Trange, 1Hz sRotation = 2MPa-0,4MPa sOscillation = 1MPa-0,2MPa (50%) E‘, E‘‘, tan(d) Size: 20mm, 0.05mm, 5mm

  23. DSC: Thermal AnalysisDetection of Tg DSCDifferential Scanning Calorimetry Power Compensated DSC Theater = constant Power = measured sample reference Thermo couple heater heater sample chamber Heat Flux DSCTdisk = const. Tsample = measured Treference = measured reference sample Constant heating disk Thermo couple

  24. DMTA in Torsion Benefits compared to alternative methods • Separate pretension and compensation of thermal expansion by the stepper motor • Oscillatory signal measured by the EC motor, without superposition of a pretension force • Optimal measuring signal, especially in borderline • areas – the extremely low temperatures below the glass • temperature (below Tg) and the high temperatures close to the melting point Benefits: • Most sensitive method • Best signal to noise ratio • Most sensitive thermal technique for Tg • Widest temperature range Application: • Enables a practically relevant dynamic load • Measurement of the true thermo-mechanical behavior

  25. Elasticity law Sir Robert Hooke 1635-1703 Poisson’s Ratio m: Rubber: 0.5 Thermo-melts: 0.35 ... 0.45 * with Poisson's ratio m [1]

  26. Poisson’s ratio µ • Rule of thumb: • For most isotropic polymers the Young’s modulus E is about 2.85 time higher than the shear modulus G • This complies to a Poisson’s ration of 0.43 Poisson’s Ratio m: Rubber: 0.5 Thermo-melts: 0.43 * with Poisson's ratio m [1]

  27. DMTA in torsion versus tension + DMTA in torsion is more sensitive than DMTA in tension + DMTA in torsion is more sensitive than DSC and delivers mechanical properties + DMTA torsion: Separate motor for measuring and pre-tension Typical DMTA in tension from competitor with conversion G‘=E‘/3, G‘‘=E‘‘/3:

  28. DMTAHow about our performance? DMA in tension (data from competition): -> issue if material becomes soft -> due to superimposed pre-tension and measuring signal Typical DMTA in tension from competitor with conversion G‘=E‘/3, G‘‘=E‘‘/3:

  29. DMTAHow about our performance? -> Tg at Peak tan(delta) delivers the same result Typical DMTA in tension from competitor with conversion G‘=E‘/3, G‘‘=E‘‘/3:

  30. glassy rubber- elastic melt DMTA: Thermo-MeltGlassy, rubber-elastic, melt tan(d) • SRF • Strain 0.01-0.1% • Frequency 1Hz • NF = 0 N • MS: SRF12 • (40x10x1)mm 1 MPa typical: 3000 MPa 100 Pa glass- transition T G‘ G“

  31. DMTA: Amorphous Thermo-MeltGlassy, rubber-elastic Amorphous random order typical: 1 MPa 3000 MPa 100 Pa glas- transition quasi rubber elastic G‘ or E‘ • SRF • Def. 0.01%-0.1% • Frequency 1Hz • NF = 0 N • MS: SRF12 • (40x10x1)mm use temperature flow region • Melt: • CP25-2/TGCP35-3/TGPP25, PP35 entropy elastic energy elastic T

  32. DMTA: Partially Crystalline Thermo-MeltGlassy, rubber-elastic Partially crystalline 1000 MPa typical: 100 Pa 3000 MPa crystalline regions G‘ oder E‘ glass transition melting region • SRF • Def. 0.01%-0.1% • Frequency 1Hz • NF = 0 N • MS: SRF12 • (40x10x1)mm use temperature flow region energy elastic T

  33. DMTA: Elastomer or RubberGlassy, rubber elastic typical: 1000 MPa 0.1MPa...100MPa permanent links glass transition G‘ oder E‘ rubber elastic • SRF • Strain 0.01% • Frequency 1Hz • NF = 0 N • MS: SRF12 • (40x10x1)mm degradation use temperature energy elastic entropy elastic T

  34. DMTA: Thermo-Plastic Elastomer (TPE)Glassy, rubber elastic + thermo-melt typical: 1000 MPa 0.1MPa...100MPa + synthetic rubber glass transition G‘ oder E‘ rubber elastic or: flow region use temperature crystalline block-copolymere thermo forming energy elastic entropy elastic T

  35. DMTA: Thermosetting Plastics typical: 3000 MPa permanent links G‘ oder E‘ degradation • SRF • Def. 0.01%-0.1% • Frequency 1Hz • NF = 0 N • MS: SRF12 • (40x10x1)mm use temperature energy elastic T

  36. DMTA - How to determine TgTg according to DMA-Method: Peak tan(d) Some years ago G‘ or E‘ could not be measured in the glassy state The measurement of the damping factor d was quite accurate Historically the Tg was calculated as the maximum in tan(d) All DMA analyzers are getting the same results for Peak tan(d) but vary in absolute measurements for E‘, E‘‘ or G‘, G‘‘ • Disadvantage of the method: • Peak tan(d) is above glassy state (approximately 10°C to 30°C) glassy rubber elastic melt sample is getting solid like (in-between rubber elastic and solid sample has reached a glassy state G‘ Tg(Peak tan-d) G‘‘ glass transition T

  37. DMTA - How to determine TgTg according to the Peak G‘‘ method: ASTM D4065 • Below Peak-G‘‘ the molecular structure is getting rigid and unflexible • Peak G‘‘ method is easy to evaluate • Disadvantage: Some polymers are not showing the Peak-G‘‘ glassy rubber elastic melt G‘ Tg (Peak G’’): Tg(Peak G’’) valuesimilartoOnset G’ G‘‘ glass transition T

  38. DMTA – How to determine TgTg according to the step analysis: (ISO 11357-1) • Analysis of step in Storage Modulus from glassy to rubbery state • Similar to DSC analysis according to ISO 11357-1 • The step can be analyzed mathematically or graphically using the tangent method • Teig is equal to Tgo T glassy rubber elastic melt Teig=Onset Storage & Loss Modulus Tmg Tefg glass transition

  39. DMTA – TgFrequency dependency of Tg • The glass transition is a relaxation process • and therefore frequency-dependent glass transition rubber elastic glassy G' tan(d) f=0.1Hz/-> 10Hz T

  40. Crystallization in Tg regionPartially crystalline polymer: ramp down and ramp up glassy rubber elastic Teig=Onset G’ Tefg T

  41. Crystallization in Tg regionPartially crystalline polymer: fast & slow cooling G’ slow cooling rapid cooling T

  42. Tg and plasticizer (additive)Mixture of polymer & plasticizer • By adding a plasticizer to a polymer • Tg can be moved towards lower temperatures • G’ can be reduced Tg % ofplasticizer

  43. CrystallizationTime & cooling rate dependent • Crystallization strongly depends on the temperature: • the rate of crystal growth • the size of the nuclei manybut small a fewbut larger Tm Tg rate ofcrystalgrowth sizeofnuclei

  44. CrystallizationIsothermal crystallization • The degree of crystallization is a time dependent process • If there is no more space for further growth the maximum degree of crystallization is reached • PP, if stored at RT, shows increasing G’ values over time (secondary crystallization process by growth in diameter and size) • Shear can also force crystallization (shear induced crystallization) maximum e.g. 90% relative degree of crystallization time

  45. DMTA – Torsion SRFMeasuring parameter • Measuring Profile: • Standard Workbook • DMTA Torsion -> DMTA Tg: SRF Rectangular Fixture • Frequency and measuring point duration • f = 1Hz and tmp=0.5min • Number of points = DT / [°C] + 1 • Strain • Start with g=0.01% below Tg • Finish with lin slope until g= 0.1% before Tm • Single check by AS if within LVE-range • Heating rate • 2K/min better lower (or practically relevant) • Precission measurements around Tg with 0.5K/min • DIN 53445: 1K/min • Pre-Tension • NF = -1N (negative = Tensional force) • Gap setting: DMTA Torsion SRF • SRF moved into position using ‚Touch Control‘ Control, Gap-Setting: Measuring profile, standard: Measuring pfofile, precise: . .

  46. DMTA TestsSRF and Touch Control (Auto tension during sample cooling) Gap setting profil: DMTA SRF Do not touch the SRF during auto detection by Toolmaster. The NF will be reset to zero during the automatic detection of the SRF. Control 1 ON = Auto NF Compensation ON Measuring position => Compensation on with 1N compression force (Control 1) Lift position => Compensation on with -1N tension (Control 1) STOP => Compensation off Warning: Without “Control 1” activated the normal force load may exceed the maximum allowed force

  47. DMTA - Tension UXFMeasuring conditions UXF: Universal Extensional Fixture • Working range • from rubber like behaviour to solid but below 2000MPa • for thin films (and fibers) • Product categories • Thermo-melts, Elastomer, Rubber, Paint films • Most common test(s) • Temperature sweep, , Shrinkage, Contraction • Recommended sample dimensions • 20mm x 5mm x 0.05mm for stiff samples • 20mm x 10mm x 0.05mm for soft samples • Typical settings • Pre-Tension 1MPa...0.2MPa • 1Hz, Amplitude 0.5MPa...0.1MPa, 2K/min, 1Point/K • e, s (tensile strain and tensile stress) • Moduli E‘, E‘‘, E* • Loss Factor: tan(d)

  48. DMTA - Tension UXFMeasuring parameter for thinn polymer films (PE, PP) Typical measuring profile for films with 5mm width: • Rotational component = pre-tension • Oscillating component = tensile stress • Sample is getting softer with T => Tensile stress should get lower

  49. EC-TwistReaction kinetics, curing or resins REACTION KINETICS Reaction Kinetics D-PP15 Tconst or range NFcontrol 1Hz (10Hz if < 100s) g = 10%-0.05% G‘, G‘‘, tan(d) D-PP08/15/25 • ISOTHERMAL or T-RAMP • Softening point • Pot life • Gel point • Curing point

  50. Curing materialsFrom raw material to final product (Epoxy resins, elastomers, adhesives) • What can be measured? • Materials before curing • Viscosity as a function of shear • Flow behaviour, yield point • Thixotropy, time dependent recovery of viscosity after shear • Curing behaviour • Isothermal test or temperature ramp • Process of curing from liquid to solid • Degree of cross-linkage • Stiffness as well as viscous and elastic properties • Final product after curing • Material characterization of the final product (DMTA) • Mechanical parameter such as G or E modulus • Temperature dependent mechanical behaviour • Working / use temperature range • Raw materials, before mixing • Liquid+chemicals (initiator) • Liquid1+liquid2 (2K adhesive) • Powder (epoxy resin)