Optical & Spectroscopic Insight into Rheology. SR Kim

Transcription

1 Optical & Spectroscopic Insight into Rheology SR Kim

2 Contents Rheology and Microscopy Rheology and Simultaneous FT-IR Analysis 2

3 3 RHEOLOGY AND MICROSCOPY

4 What does Rheology Do? Put a defined mechanical stress or strain onto a sample Record the sample s macroscopic response Sample is a homogeneous black box Reasons are hidden in the microscopic structure To find out why, we need a microscopic method Correlate microscopic with macroscopic information 4

5 Separate Data Collection the Classical Approach Microscope image from sample (at rest) before measurement Rheological measurement Microscope image from sample (at rest) after measurement Different sample, sample history, preparation and time! Extra time to prepare sample twice! 5

6 Simultaneous Data Collection Rheological data Images Example: Polyethylene 6

7 Investigation of structural changes under shear flow Different illumination techniques Light from bottom (standard) Rotor Sample Good for transparent and semi itransparent tsamples Low concentration of particles Broad particle size distribution Glass plate Lens 7

8 Investigation of structural changes under shear flow Different illumination techniques Light from top (using transparent rotor) Light source Glass rotor Sample Good for more opaque samples Higher concentration of particles Narrow particle size distribution Glass plate Lens 8

9 Low contrast emulsion: Contrast enhancing illumination Using illumination from the side Silicone oil S1000 (<5%) In mineral oil E6000 (>95%) Illumination from bottom Illumination from side 9

10 Low contrast emulsion: Contrast enhancing illumination Using illumination from the side A closer look Higher contrast Additional information 3µm Droplets 1.5µm Droplets 10

11 Emulsions at higher shear rates Using a stroboscope Sample: Silicon oil in mineral oil at different shear rates Using a regular cold light source: 630 s s s -1 Using a stroboscope light source: plate/plate measuring geometry, polished rotor, gap: 50 µm 630 s s s s -1 11

12 Emulsions at higher shear rates Using a stroboscope Investigation of droplet rupture even at very high shear rates! Shear rate = s -1 12

13 Application fields Formulation - Product definition Study of rheological phenomena and structural changes, e.g. Shear thinning Emulsification Shear thickening Gelification Thixotropy Disaggregation g Aging Crystallization Flocculation Process optimisation Quality Control / Research - Viscosity - (Particle) Size - Homogeneity 13

14 Melting Behaviour of Polymers Sample: POM pellets in PE matrix fluid Temperature ramp using constant shear rates Structural formula of POM Selected images from melting behavior Influence of granulation speed on the melting behaviour of a POM granulate in a PE melt. Heating rate 0.2 K/min 14

15 Mixing Behaviour of Polymer / Masterbatch Sample: masterbatch in PE matrix fluid Rotation-Time experiment (190 C, 50 rpm) At the beginning molten PE and Masterbatch PE masterbatch droplets Optimization of mixing time and quality continuous mixture of masterbatch 15

16 Solubility of a crystalline drug in hot melt polymer BASF Kollidon VA64 powder on Fenofibrat powder initially crystalline Fenofibrat: white with crossed polarization filters Heating rate 5 K/min Cooling rate 5 K/min 16

17 Solubility of a crystalline drug in hot melt polymer BASF Kollidon VA64 powder on Fenofibrat powder initially crystalline Fenofibrat: white with crossed polarization filters Heating rate 5 K/min Cooling rate 5 K/min 17

18 18 SIMULTANEOUS FT-IR

19 Simultaneous FT-IR INTRODUCTION 19

20 Why Combine Rheology with IR-Spectroscopy? Rheometer Macroscopic properties With a rheometer, we analyse a material s viscoelastic properties as a function of stress and deformation Macroscopic properties Microscopic structure Viscoelastic properties are related to a material s structure and or structural changes on a molecular scale Microscopic structure IR-Spectroscopy With a spectroscopic method, we analyse a material s microscopic structure and its changes 20

21 FTIR and Rheometry Classical Approach IR-spectrum at beginning Rheological Test IR-spectrum at end Absorbance Units Absorbance Units Wavenumber cm Wavenumber cm Up till now at least 2 separate tests 2 different samples 2 times sample preparation More time for running 2 methods Different sample preparation Different test conditions No direct correlation of the results No spectra during the mechanical test 21

22 Simultaneous FT-IR THE TEST SETUP 22

23 Instrument Setup Simultaneous data acquisition IR acquisition rate can be chosen to fit application 23

24 The Rheonaut Module Patented Module* Temperature ranges Peltier: C Electrical: RT 400 C DTGS- or MCT-detector ATR-crystal with 1 mm 2 surface, single reflection Module can move sideways for different diameters Fully integrated software with e.g. Nicolet OMNIC HAAKE RheoWin sends spectroscopy parameters HAAKE RheoWin triggers collection of spectra Spectroscopy software collects spectra Data is correlated via time code Simultaneous data collection * Resultec Analytic Equipment: DE , EP , US , JP

25 ATR Rheonaut: Attenuated ATR working Total Reflection principle - Working Principle Penetration depth depends on wavelength, around 3-10 m D p 4 10 D p 2 2 ns sin nc nc with: D p : Penetration depth (µm) : Wavenumber (cm -1 ) n c : Refractive index of crystal n s : Refracitve index of sample : Angle of incidence 2 25

26 Advantages of the ATR-Principle Test done on the same sample Optimum test conditions for rheometer Optimum test conditions for spectrometer Penetration depth usually 3 10 µm by Resultec Analytical Instruments 26

27 Simultaneous Data Collection RheoWin OMNIC 27

28 Simultaneous FT-IR EXPERIMENTAL RESULTS 28

29 Curing of a PU Foam - Background Application: insulation of refrigerator bodies Main problems during production process: Build-up of foam disturbed by shear Curing to fast, so foam does fill the whole volume 1 commercial product was compared with 1 R&D product Commercial product had a good performance R&D product did not perform well Setup used: HAAKE MARS 29 Rheonaut-module with Peltier temperature control

30 PUR Foam in FT-IR Relevant Bands Commercial product 3325 cm cm cm -1 N-H CH 2, CH 3 N=C=O Stretching Stretching Stretching Main reaction between HDI and synthetic polyol 1725 cm cm cm -1 C=O C=O C=O Urethane Stretching t Urethane Stretching Stretching cm -1 HN-C=O (Amide II) Combined Stretching and Deformation Absorban nce Units Wavenumber cm Wavenumber cm

31 PUR Foam Curing Monitored via FT-IR Spectrum taken after: 0 min 20 min 40 min 50 min 60 min 70 min 80 min NCO stretching decreasing HNCO (Amide II) combined motion increasing C=O/ urethane (non-bonded) stable Abs sorbance Units Wavenumber cm-1 Wavenumber cm-1 31

32 PUR Foam in Oscillatory Shear + FT-IR Absorpt tion Units 0,6 1,00E+06 0,55 0,5 1,00E+05 0,45 0,4 0,35 1,00E+04 Isocyanate 2260 cm-1 0,3 Amide II 1510 cm-1 Urethane 1725 cm-1 G' 0,25 G'' 1,00E+03 0,2 0,15 G', G''/Pa Rheology clear function of ongoing chemistry Increase of G function of amide bond concentration Increase of G function of air bubble concentration Quick Reaction as free Urethane stays at constant level 0,1 1,00E+02 0 Time/min 80 32

33 PUR Adhesive Curing Monitored via FT-IR Spectrum taken after: NCO stretching decreasing 0 min 30 min min 90 min Absorbance Units min 180 min C=O/ urethane (non-bonded) decreases HNCO (Amide II) combined motion increasing Wavenumber cm Wavenumber cm

34 PUR Adhesive in Oscillatory Shear + FT-IR Absorptio on Units Isocyanate 2265 cm-1 0,35 Urethane 1740 cm-1 1,00E+06 Amide II 1520 cm-1 0, ,25 0,2 0,15 G' 1,00E+05 G'' Increase of G function of amide 1,00E+04 bond concentration 1,00E+03 1,00E+02 1,00E+01 / Pa G', G''/ Slow Reaction as free Urethane concentration decreases 0,1 0,05 1,00E+00 1,00E E02 1,00E-02 No chemical indication why curing speeds up at t 100 min 0 0Time Time/ min 1,00E-03 34

35 35 Curing of an 2K Acrylate Glue the Rheology Part

36 Curing of an Acrylate the Chemistry Behind Starter t + Monomer = Polymer 36

37 Curing of an Acrylate the Spectroscopic Part First Spectrum Last Spectrum 37

38 Curing of an Acrylate the Spectroscopic Part First Spectrum Last Spectrum 38

39 39 Time Dependant Spectroscopic Data

40 40 Rheological and Spectroscopical Data Combined

41 UV Induced Curing of an Acrylate Based Coating Dual layer coating system Up to 1000 m/min. How to minimize Energy Footprint? 41

42 UV Curing of an Acrylate Based Coating Strain was 0.01 UV was triggered after 30 s Exposure Time: 200 ms Every 10 s triggered for same 200 ms 6.5 Orders in G Afterwards only post-curing Rigidity has to be fine-tuned! 42

43 Variation of UV-Intensity Rheological Results Start of UV irradiation Increasing intensity UV-intensity is reflected in δ, plateau value reached faster with higher intensity 43

44 Variation of UV-Intensity Spectroscopic Results UV intensity influences initial curing speed 44

45 Outlook Rheology can be correlated online with chemistry PU foam 2K acrylate UV-curing acrylate Rheology can be correlated with structural changes via Optical Module On-line FT-IR Module 45

46 Thank you for your attention What are Your questions? 46