Relative humidity as a new parameter in rheological testing

Transcription

1 Engineering Conferences International ECI Digital Archives Colloidal, Macromolecular & Biological Gels: Formulation, Properties & Applications Proceedings Relative humidity as a new parameter in rheological testing Jörg Läuger Anton Paar Germany, joerg.laeuger@anton-paar.com Gunther Arnold Anton Paar Germany Follow this and additional works at: Part of the Engineering Commons Recommended Citation Jörg Läuger and Gunther Arnold, "Relative humidity as a new parameter in rheological testing" in "Colloidal, Macromolecular & Biological Gels: Formulation, Properties & Applications", ECI Symposium Series, (2016). This Abstract and Presentation is brought to you for free and open access by the Proceedings at ECI Digital Archives. It has been accepted for inclusion in Colloidal, Macromolecular & Biological Gels: Formulation, Properties & Applications by an authorized administrator of ECI Digital Archives. For more information, please contact franco@bepress.com.

2 ECI Gels / Hernstein Austria / July 2016 Humidity as a new parameter in rheological testing Jörg Läuger, Gunther Arnold Anton Paar Germany

3 Three Categories of Combined Techniques Structural Information Additional Information on the Micro-Structure simultaneous to the rheology Additional Parameter Rheological testing under simultaneous application of additional parameters Non rotational shear rheology Use of the rheometer to perform nonclassical shear rheology SALS Microscopy (Polarized, Fluorescence, Confocal) Birefringence Dichroism Visualization: PTV, PIV Polarized Imaging (SIPLI) IR / NIR / Raman Spectros. SAXS / SANS Dielectric Spectroscopy Temperature Pressure Magnetic Field Electric Field UV-Light Water Reduction Humidity DMTA in Torsion and Tension Extensional Rheology Tensile Testing Tack Interfacial Rheology Tribology Powder Rheology

4 Humidity or Moisture Content Background Humidity control in mechanical testing: Some DMTA Instruments offer Humidity Option limitations with respect to geometries, samples and measuring ranges Modified commercial oven Measurements in extension on PE-films and membranes for fuel cells with a SER geometry

5 Humidity Ready temperature system Peltier based convection oven In standard operation: -20 C Can be turned into humidity control chamber Shaft cooling Rubber sealing Humidity sensor Humidity sensor Drain Window

6 Humidity control system for the MCR Rheometer Humidity Sensor

7 Humidity Generator

8 Humidity Option: Range and Performance Range of Relative Humidity Performance of Humidity Control 5% - 95% RH dependent on temperature Humidity ramp from 10% to 90% RH No overshot in RH when ramping up Stable set relative humidity reach within about 5 minutes Fast drying possible

9 Humidity Option: Range and Performance Range of Relative Humidity Performance of Humidity Control 5% - 95% RH dependent on temperature Ramps in RH at constant T

10 Humidity Option: Range and Performance Range of Relative Humidity Performance of Humidity Control 5% - 95% RH dependent on temperature Ramps in T at constant RH

11 Different rheometer designs CMT Combined Motor Transducer SMT Separate Motor Transducer Counter Rotation or Counter Oscillation Torque signal from motor current (M ~ I) MCR 702 TwinDrive

12 Geometries Different geometries: cones, plates, modified ring (dent), solid rectangular fixture (SRF-torsional DMTA), UXF (extensional DMTA), SER (extensional rheology), ball-on-threeplates (BTP-tribology) SRF UXF SER BTP

13 Humidity: Gelatine bar at 50 C 35 x 10 x 0.2 mm 0.01% Strain, 1Hz 30% Relative Humidity: Stable values G >> G : brittle solid gelatin plate 80% Relative Humidity: G and G decrease due to wetting and swelling. Soft viscoelastic solid, G > G (less brittle) Back to 30% Relative Humidity: Drying of the gelatin, back to almost the initial mechanical properties

14 Variation in Humidity: Cookie Biscuit (20 x 10 x 5 mm) Strain: % Frequency: 1 Hz 25 C RH = 30 %; t = 4 min RH = 80 %; t = 8 min RH = 10 %; t = 18min Biscuits exposed to moisture absorb water leading to a decrease in G and G Will not crack the same way as under initial conditions Not giving a fresh impression to the consumer. Drying of the biscuit is possible to some extend but the initial structure does not fully recover

15 Chewing Gum Time Test Before Test After 60 min at 37 C and 80% RH (35 x 10 x 1.7 mm) Strain: % Frequency: 1 Hz 25 C and 30% RH: No impact of RH on structure over 60 min 37 C and 30% RH: No impact of RH on structure but moduli are lower due to higher temperature 25 C and 80% RH: Continuous decrease of G and G, water soluble bulk sweetener are dissolved and build syrup layer on the surface 37 C and 80% RH: More sweetener dissolved, thicker syrup layer, faster decay of moduli Extensional Rheology of chewing gum: L.Martinelli et al. J Rheol 58, (2014)

16 Tack Test (1N contact force): Chewing Gum Before and after conditioning at 37 C and 80%RH 10% RH: no stickiness; 37C and 80% RH: Adhesives forces over larger displacement Extensional Rheology of chewing gum: L.Martinelli et al. J Rheol 58, (2014)

17 Humidity Impact in Food Systems Example Chewing Gum (35 x 10 x 1.7 mm) Settings Preconditioning: 30 min Tack Test: Normal Force: 1 N (25 s) Lifting Velocity: 0.1 mm/s Geometry: PP15 Before Test 60 min at 37 C/ 80% RH 25 C and 10% RH: No stickiness detected 37 C and 10% RH: Not stickiness detected 25 C and 80% RH: Adhesives forces indicate stickiness due to dissolved sweetener 37 C and 80% RH: Adhesive forces over larger displacement Extensional Rheology of chewing gum: L.Martinelli et al. J Rheol 58, (2014)

18 Water absorption of Polyamide SRF: f = 1 Hz; γ = 0.01 % T = 50 C; RH = 5, 10, 20, 30, 40, 50% Sample at ambient conditions Temperature ramps at RH = 5, 10, 15% Sample predried in oven Below 20%RH drying Above 20%RH water absorbing Maximum in G shifted to lower temperatures for increasing RH

19 Extensional Oscillation of polymer films at varying RH Pre streched polymer films (thickness: 0.01mm; width: 5mm) measured with UXF T = 30 C, f = 1Hz, ε = 0.03% Large differences between the three films

20 Starch based wallpaper glue at different humidity values PP50, 1%, 10rad/s 25 C 10% RH 30% RH 50% RH As dryer the conditions as faster the curing

21 Special Dent Geometry for humidity measurements Parallel-plate: Different behavior at the edge and the inner part Sample between the dents Defined geometry, i.e. absolute rheological values Humidity penetrates easily into the sample Modified ring (dent) geometry ( out = 32 mm; in = 28 mm)

22 Special Dent Geometry for humidity measurements Wallpaper glue: 1% strain ω = 10rad/s 25 C 10% RH red 30% RH grey 50% RH - black With Dent-Geometry curing behavior is much better attributed to a specific humidity

23 Silicone RTV (Room Temperature Vulcanization) Rubber Influence of RH at constant temperature T = 45 C ω = 10 rad/s γ = 0.1 % Curing is affected by the reaction between the stabilizers and the moisture As higher the RH as faster the chemical reaction Difference between the 2 silicon rubber RH is one key parameter for an optimum curing process

24 Silicone RTV (Room Temperature Vulcanization) Rubber Influence of temperature at constant RH RH = 50% ω = 10 rad/s γ = 0.1 % Curing is affected by the reaction between the stabilizers and the moisture As higher the temperature as faster the chemical reaction Difference between the 2 silicon rubber Simulation of real process conditions only by controlling T and RH

25 Humidity initiated curing of a 1K-PUR (polyurethane) Influence of RH at constant temperature T = 25 C ω = 10 rad/s γ = 0.1 % Curing is affected by the reaction between the stabilizers and the moisture As higher the RH as faster the curing process Simulation of real process conditions only by controlling T and RH

26 1K PU Polyurethane adhesive T = 60 C f = 1Hz γ = 20 % 60% RH 40% RH 20% RH As higher the RH as faster the curing process

27 RH dependence of Static Friction (Stiction) Ball-on-3-Plates (BTP) Rheo-Tribometer P Heyer, J Läuger: Lubrication Science 21 (7), (2009) Dry conditions, i.e. no extra lubricant

28 RH dependence of Static Friction (Stiction) Static Friction (Stiction) increases with increasing humidity

29 Conclusions Humidity system for rheometer to control the RH in the range from 5 to 95% over a large temperature range Full integration in rheometer software Temperature ramps at constant RH RH ramps at constant temperature Works with single motor and double motor rheometer Large range of different geometries: SRF, UXF, SER, Tribo, PP, CP, modified ring (dent), Tack, Relative humidity or moisture content is a crucial parameter in many different applications: Food, Polymers, Films, Sealants, Adhesives, Lubricants, Hydrogels, Biomaterials, Tribosystems,

30 Thank you for your attention