Advanced rheometric tools for polymer applications Gunther Arnold a - - PowerPoint PPT Presentation

www.anton-paar.com

Advanced rheometric tools for polymer applications

Gunther Arnolda, Sandra Lanterib, Jörg Läugera

a Anton Paar Germany b Anton Paar Italia

MIPOL2017 – Milan February 2017

www.anton-paar.com

Cone Partitioned Plate

Edge fracture Ø Deformation of the sample surface Ø Propagates radially Function of time Function of deformation Ø Limits accuracy of Start up shear measurements Flow curves LAOS measurements

Mattes, K.M., Vogt, R., Friedrich, C.(2008) Analysis of the edge fracture process in

• scillation for polystyrene melts.

Rheo Acta 47 929-942

www.anton-paar.com

Cone Partitioned Plate

Edge fracture Ø Deformation of the sample surface Ø Propagates radially Function of time Function of deformation Ø Limits accuracy of Start up shear measurements Flow curves LAOS measurements

Mattes, K.M., Vogt, R., Friedrich, C.(2008) Analysis of the edge fracture process in

• scillation for polystyrene melts.

Rheo Acta 47 929-942 Edge fracture effects in PDMS as a function of the set deformation

www.anton-paar.com

Cone Partitioned Plate

Limiting the effects from edge fracture and fracture propagation Cone Partitioned Plate Ø larger strain rates in rotational testing Ø larger amplitudes in oscillatory testing

Schweizer, T. (2003) Comparing cone partitioned plate and cone standard plate shear rheometry of a polystyrene melt. J Rheo 47, 1071-1085

www.anton-paar.com

Limiting the effects from edge fracture and fracture propagation Example: Amplitude Sweep

Cone Partitioned Plate

Sample: PDMS Frequency: 1 rad/s Strain: 1 % - 1000 % Temperature: 25 °C

www.anton-paar.com

Limiting the effects from edge fracture and fracture propagation Example: Start up shear measurement

Cone Partitioned Plate

Sample: PDMS Shear rate: 0.1/1/5/10/30 1/s Temperature: 25 °C

www.anton-paar.com

Cone Partitioned Plate

Stress growth after step shear rate

• Determination of material constants of the Wagner damping function
• Prediction of extrudate swell as influenced by the aspect ratio of capillary dies

HDPE at 200°C

Simulated vs. experimental swell profiles

www.anton-paar.com

Rheology and combined Techniques

§ Optical techniques:

• SALS (Small Angle Light

Scattering)

• Microscopy
• Polarized Light Imaging
• Particle Image Velocimetry

§ SAXS § SANS § Dielectric spectroscopy

Additional information

• n the micro-structure

simultaneous to rheology Macroscopic material functions Microscopic structure parameters Rheometry Microscopy Rheo-Microscopy Example: Rheo-Microscopy:

www.anton-paar.com

Rheo - Microscopy

Droplet size and shape is related to the shear rate and shear history Advantage: Interrelation between macroscopical behavior (rheology) and microstructural origin

W/O Emulsion

Drawback: Structure of interest moves out of the microscopic view to fast.

www.anton-paar.com

Counter rotation produces a stagnation plane

• Structures are stretched and rotated but not moving
• Same structures can be followed

Rheo - Microscopy: Counter Rotation

www.anton-paar.com

Shear flow direction

PIB in PDMS Bottom View Side View

Shear flow direction Neutral

• r Vorticity

direction Shear gradient direction

Counter rotation produces a stagnation plane

• Structures are stretched and rotated but not moving
• Same structures can be followed

Rheo - Microscopy: Counter Rotation

www.anton-paar.com

Shear flow direction

PDMS in PIB Counter rotation produces a stagnation plane

• Structures are stretched and rotated but not moving
• Same structures can be followed

Bottom View Side View

Shear flow direction Neutral

• r Vorticity

direction Shear gradient direction

Rheo - Microscopy: Counter Rotation

www.anton-paar.com

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 § Customized solutions § Modified commercial oven § Measurements in extension on PE-films and membranes for fuel cells with a tool for extensional rheometry (SER) § Monitoring the impact of water as plasticizer

www.anton-paar.com

Humidity - Impact in Polyamide

Example Polyamide 6.6 at 50 °C Stepwise humidity change Sample pretreatment

• stored at ambient conditions

Below 20% relative humidity

• water desorption

Above 20% relative humidity

• water absorption

Water behaves like a plasticizer Settings Frequency: 1 Hz / Strain: 0.01% Relative Humidity: 5/10/20/30/40/50%

www.anton-paar.com

Humidity - Impact in Polyamide

Example Polyamide 6.6 Temperature ramp at various but constant relative humidity

• Maximum in G‘‘ shifted to lower

temperatures for increasing RH

• Reduction of Tg due to increase
• f RH

Settings Sample predried (12 h; 50 °C; 5% RH) Frequency: 1 Hz / Strain: 0.01% Heating rate: 1K/min

www.anton-paar.com

Example Polyurethane 2 Interval stepwise humidity change Interval I: RH = 5%

• Dominant viscous properties

Interval II: RH = 20/40/60%

• Increase of G′ and G″
• Cross-over
• Approach to plateau values

Decreasing relative humidity:

• Slower curing reaction

RH is one key parameter for an optimum curing process Settings Frequency: 10 rad/s Strain: 20% Temperature: 60 °C

Humidity – Impact on Curing Reactions

www.anton-paar.com

Conclusions

Limiting the effect of edge fracture § Cone Partitioned Plate geometry and Separate Motor Transducer Mode reduce measuring errors at large deformations § Extended deformation range for LAOS and Start up shear measurements Rheology and Microstructural Analysis § Interrelation between macroscopical behavior and its microstructural origin Impact of ambient conditions § Characterizing mechanical parameters as function of Relative Humidity § Humidity Option enables to simulate processing/storage conditions

www.anton-paar.com

Thank you for your attention