Back to Basics - Thermo Fisher...
Transcript of Back to Basics - Thermo Fisher...
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Back to Basics Fundamentals of Polymer Analysis Using Infrared & Raman Spectroscopy
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Molecular Spectroscopy in the Polymer Manufacturing Process
Raman Microscopy
Production
QC
Routine FT-IR
NIR
Advanced FT-IR FT-IR Microscopy
Process NIR
Receiving
R&D
Shipping
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Molecular Spectroscopy Helps the Entire Supply Chain
FT-IR, NIR
FT-IR, Raman, NIR, Infrared & Raman microscopy
FT-IR, Raman, NIR, IR & Raman microscopy, TGA-IR
Material Characterization Control & Monitoring
Incoming Material ID & Verification
Material Deformulation Root Cause Analysis Reverse Engineering
FT-IR, Raman, NIR, IR & Raman microscopy, TGA-IR
Adds Value for:
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Wavenumbers (cm-1)
Wavelength (m)
The Electromagnetic Spectrum
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x-rays ultraviolet
visible
near-IR
mid - IR far-IR
XRF UV-Vis Infrared
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radio
Technique
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Stretching Deformation
Bending Twisting
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Molecular Vibrations Produce Spectral Fingerprints
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Sample Handling
Transmission Solids, Liquids, Gases
Attenuated total reflectance (ATR) Solids, Liquids, Gels, Pastes and more
Diffuse reflectance (DRIFTs) Powdered solids in a KBr matrix
Specular reflectance Films and coatings on reflective surfaces
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Aris Associates Ltd2010
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Transmission Sampling
Most often used for quantitative measurements Co-polymer ratios Polymer additive levels
Provides results more representative of bulk sample Hot-melt films often prepared from 25 500 microns
Bulk Polymer - saturated absorbance
50 micron thick film
Additive - on-scale absorbance
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ATR Sampling - Attenuated Total Reflectance
Most popular, easy to use FT-IR sampling technique Mainly for qualitative material identification/verification
Diamond crystal often used (Germanium for carbon-filled materials) Surface analysis technique
IR light penetrates about 2 4 micrometers into the sample May require sample surface cleaning or excision
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FT-IR Identifies Various Polymers
Aromatic (PS, SAN, ABS, PET etc.) vs. aliphatic (PE, PP, PVC etc.), and more Infrared clearly differentiate aliphatic and aromatic polymers Low and high density Amorphous vs. crystalline chains
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FT-IR Detects Differences Within Similar Polymers
Similar polymers, with different structure Infrared can reveal structural differences within the same class of compound
Example: Nylon 6,6 and Nylon 6,12 spectral differences
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HDPE High Density Polyethylene (low methyl CH3 groups shows none or little absorption at 1375) LLDPE Linear LDPE (1375 peak of CH3 groups shifted depending on copolymer C4, C6 or C8); butene shows a 770 peak. LDPE Low Density Polyethylene (high CH3 methyl groups shows intense 1375 peak)
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HDPE High Density Polyethylene (low methyl CH3 groups show none or little absorption at 1375)LLDPE Linear LDPE (1375 peak of CH3 groups shifted depending on copolymer C4, C6 or C8); butene (C6) shows a 770 peak.LDPE Low Density Polyethylene (high CH3 methyl groups show intense 1375 peak)
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FT-IR can Detect Differences Within Similar Polymers
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Infrared Quantitative Analysis
Polymer manufacturers develop hundreds of methods for Co-polymers monomer ratio Additives concentration
Std EVA 32.6% bStd EVA 5.3% bStd EVA 28%Std EVA 24.6% bStd EVA 18.2%Std EVA 9.1%Std EVA 15.2% b
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Examples: Vinyl acetate in EVA Ethylene, butene in terpolymer olefins Acrylonitrile in styrene acrylonitrile Tinuvin, Chimassorb UV stabilizers Plasticizers in PVC
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Common Additives Characteristic IR Spectra
Additive: IR Frequency: Irganox 1010 1746 cm-1 Irganox 1076 1741 cm-1 Irganox 3114 1697 cm-1
Irgafos 168 1215 cm-1
BHT 3648 cm-1
Chimasorb 944 1560 cm-1
Erucamide 3365 cm-1
Tinuvin 622 1738 cm-1
Polyethylene film with Erucamide
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Irganox 1076 Quantitative Analysis in Polyethylene
Irganox peak
Polyethylene 2020 cm-1 thickness correction band
Calibration curve Built-in quant analysis report
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Multi Component Quantitative Analysis in Polyethylene
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NIR Spectroscopy
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NIR Near-infrared Spectroscopy
Measures weak harmonics of the mid-infrared region
Many sampling benefits over Mid-IR: Deeper penetration for more representative sampling Light transmits through glass Allows use of fiber optics
Good for : Co-polymer ratios Correlation to other physical/chemical methods, such as density Some additive levels
Main disadvantage of NIR: Requires extensive modeling of material to obtain working method
Most common sampling techniques Diffuse reflectance Transmission/Transflection
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Density of Polyethylene by NIR
Calibrate the instrument for density Classify new PE batches by density
No sample preparation Load the spinning sample cup Qualify sample
Catalyzed
Polymerization
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Density of Polyethylene by NIR
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Ethylene in PP: 2% to 16%
Ethylene/Polypropylene Copolymer Ratio by NIR
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At Line Cross-Linked Polyethylene (PEX) by NIR
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Process Control by Multi-Channel NIR
Antaris MX
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Raman Spectroscopy
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Raman Spectroscopy
Laser-based technique, visible and near-IR lasers Laser light interacts with vibrations of molecules and scatters at a shifted
wavelength Analysis of the shifted, scattered light provides a vibrational spectrum
reveals molecular structure Excellent microscopy technique Downside
Many samples have significant fluorescence interferences Sampling is not representative due to focused laser beam
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Raman vs. Infrared Spectroscopy
A technique similar to infrared spectroscopy
Both molecular vibrational techniques Used to characterize covalently bonded materials
Both useful for Micro and macro sampling Solids and liquids Organic and inorganic materials
Both give definitive identification of unknown material
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Raman shift (cm-1)
For a more in-depth introduction we also have a recorded webinar and other material.
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Raman Compared with Infrared
Complementary information End functional groups dominant in infrared spectrum Molecular backbone dominant in Raman spectrum
Raman often useful for characterizing morphology Weak IR absorbers often strong Raman emitters and vice versa
Aqueous solutions pose fewer challenges with Raman
FT-IR Transmission Spectrum
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Nylon 6 Nylon 6,6
Nylon 6
Nylon 6,6
Raman can Detect Differences Within Similar Polymers
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Raman is the Ideal Choice for Crystallinity Studies
Raman spectra of crystalline and amorphous polyethylene tere-phthalate (PET) films
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Analysis of Inorganics in Polymers by Raman
Two polymorphs of TiO2 Two peaks are characteristic of Rutile Third peak is characteristic of Anatase
Infrared spectrum of TiO2 is not as much informative Its spectrum does not show sharp well-isolated peaks
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Summary
Molecular spectroscopy is a good tool for polymer analysis Mid-infrared is an excellent all-around tool Near-infrareds sampling advantages help get it out of the lab Ramans unique capabilities to supplement infrared analysis
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Todays Spectroscopic Analysis of Polymers
Simplified by Thousands of spectra in Search libraries Knowledge base allowing the
understanding of polymers in infrared spectroscopy
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Please Contact Us for More Information
View our website: www.thermoscientific.com/polymers
or
Please feel free to email me: [email protected]
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Back to BasicsFundamentals of Polymer AnalysisMolecular Spectroscopy in the Polymer Manufacturing ProcessMolecular Spectroscopy Helps the Entire Supply ChainThe Electromagnetic SpectrumMolecular Vibrations Produce Spectral FingerprintsSample HandlingTransmission SamplingATR Sampling - Attenuated Total ReflectanceFT-IR Identifies Various PolymersFT-IR Detects Differences Within Similar PolymersFT-IR can Detect Differences Within Similar PolymersInfrared Quantitative AnalysisCommon Additives Characteristic IR SpectraIrganox 1076 Quantitative Analysis in PolyethyleneMulti Component Quantitative Analysis in PolyethyleneNIR SpectroscopyNIR Near-infrared SpectroscopySlide Number 18Slide Number 19Slide Number 20At Line Cross-Linked Polyethylene (PEX) by NIRProcess Control by Multi-Channel NIRRaman SpectroscopyRaman SpectroscopyRaman vs. Infrared SpectroscopyRaman Compared with InfraredRaman can Detect Differences Within Similar PolymersRaman is the Ideal Choice for Crystallinity StudiesSlide Number 29SummaryTodays Spectroscopic Analysis of PolymersPlease Contact Us for More Information