hyphenated spectroscopy techniques - ta instruments · 2000-08-31 · hyphenated spectroscopy...
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Basic Theory and Instrument Design of FT-IR
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Thermal Analysis and Rheology Short CourseConcord, NHApril 10, 2018
Hyphenated Spectroscopy Techniques
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Analytical Instruments Overview
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Chromatography & Mass Spectrometry
Chemical AnalysisInstruments
Materials & Structural Analysis
• Life sciences mass spectrometry
• Liquid, ion, gas chromatography
• Inorganic/trace elemental analysis
• Laboratory informatics
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• Molecular and elemental spectroscopy
• 2D/3D imaging software
• Portable analytical instruments
• Air-quality monitoring
• Radiation safety and security
• Process instruments
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Revenue ending in Q1 2017
Basic Theory and Instrument Design of FT-IR
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The widest range of analytical methods to drive deeper materials insights
EDS
Elemental imaging at high spatial resolution
Raman
Chemical compound
identification
Identification of both
organic and inorganicmaterials
FTIR
Chemical compound
identification
Identification of organic
materials in bulk state
XRF
Bulk state elemental
composition
XRD
Structural crystallinity
and composition
XPS
Surface analysis
quantitative chemical
state
We deliver a full spectrum of analytical tools that enable customers to advance their research, product development, and quality control capabilities
UV-Vis
Quantitative measurement of reflection
or transmission properties of
a material
Electron Microscopy
Multiscaleimaging & analysis of
various materials
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Wavenumbers(cm-1)
Wavelength (µµµµm)
The Electromagnetic Spectrum
107 106 105 104 103 102
x-rays
ultraviolet
visible
near-IR
mid - IR
far-IR
XRF UV-Vis Infrared
10-3 0.01 0.1 1 10 100
radio
Technique
Range
Basic Theory and Instrument Design of FT-IR
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• Work fast…
• Little or no sample prep, rapid screening
• …on a range of samples…
• Organics, inorganics, films, coatings, paper, fibers, more
• …and answer fundamental questions
• What is this stuff? How much is in there? In what form?
• Analyze samples from ‘cradle to grave’
• R & D, process control, QA/QC, failure analysis, waste
The Power of Molecular Spectroscopy
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Core Molecular Spectroscopy Techniques
FTIR• Chemical fingerprint • Fast analysis
picoSpin NMR• Benchtop NMR• No cryogens
Raman Spectroscopy• Chemical fingerprint • Fast analysis• Greater sampling options –microscopy options
Basic Theory and Instrument Design of FT-IR
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• Energy varies along the x-axis
• Wavelength in nanometers or microns, Wavenumber (cm-1)
• Response is along the y-axis
• Absorbance, transmittance, reflectance
• Different molecules absorb light differently (“Peaks”)
• This is what enables spectroscopy to tell us something!
General ‘Rules’ for Molecular Spectroscopy
Energy
Re
sp
on
se
“Peaks”
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Polymer Deformulation Studies using FT-IR Coupled to TGA
Breaking it Down
Basic Theory and Instrument Design of FT-IR
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Overview
• Deformulation
• What is it?
• Why do it?
• Common materials
• FT-IR as a deformulation tool
• Classical technique
• TGA coupled with FT-IR
• Physical property correlation with chemical data
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Deformulation
• Reverse Engineering
• Unknown material composition
• Failure Analysis
• Known material gone wrong
• Polymers
• Plastics
• Fillers
• Formulation
• Rubber
• Carbon Black: O-Rings, Tires
• Epoxies, Resins, Adhesives
• Entrained solvents, Breakdown products
• Fabrics, Paper products
Basic Theory and Instrument Design of FT-IR
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TGA-IR: The Basics
Vapor
IRBalance
Pan
Heated TransferLine
Temperature Ramp
Weight Loss Curve
Derivative Weight Loss Curve
Infrared Series File
Quantitative: How much is coming off?T “G” A – Gravimetric Analysis
Qualitative: What is coming off?FT-IR – Chemical information
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TG
A F
urn
ac
e
TransferGas In
Sample
Heated Transfer Line
IR BeamIR Beam
FT-IR Spectrometer
Exhaust
0.0
0.1
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1.0
Absorb
ance
500 1000 1500 2000 2500 3000 3500 4000
Wavenumbers (cm-1)
Infrared Spectrum
H2O
H2OH2O
H2O 0.1
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Ab
so
rba
nce
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Wavenumbers (cm-1)
CH4CH4
CH4
CH4 0.05
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Ab
so
rba
nce
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Wavenumbers (cm-1)
CH4
CH4
TGA-FTIR: Experiment
TGA Gas Cell
TGA Gas Cell
Basic Theory and Instrument Design of FT-IR
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Experimental Set-up
Low Volume
IR Gas CellTGA Conditions
• Sample size: 10 – 15mg
• TGA program: N2 Purge Isothermal
• Temperature : Ambient up to 650 C
FT-IR Conditions• Transfer line temp: 300 C
• TGA-IR Module temp: 300 C
• Data Collection: 8 cm-1, 5 scans/spectrum
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Simple Situation – Calcium Oxalate
• Three weight-loss peaks
• H2O ; CO + CO2 ; CO2
• H2O
Basic Theory and Instrument Design of FT-IR
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• Polymers
• Textiles
• Coatings
• Residual solvent
• Product stability
• Additive analysis
Example Applications
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Good
Bad
Subtraction
Good
Bad
Search result
Gasket analysis
Classic Root Cause AnalysisClassic Root Cause Analysis
Basic Theory and Instrument Design of FT-IR
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• These nanoparticles are stabilized by ligands
• Heating breaks down the complexes, releasing ligand
Deformulating Nanoparticles
TOPO
ODPA
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• A critical electronic component, in a sealed chamber, was degrading
• Concern was for outgassing of other materials in the chamber
• The insulation of a wire was found to be the cause
Outgassing of Electronic Component
Formaldehyde
Water
Basic Theory and Instrument Design of FT-IR
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Complete Analysis: Mercury TGA
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Polycarbonate Poly(acrylonitrile:butadiene:styrene)
Polycarbonate/Poly(acrylonitrile:butadiene:styrene)(PC+ABS)
Blended Polymer – Complex Matrix
PC+ABS Characterization
Basic Theory and Instrument Design of FT-IR
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PC+ABS Characterization: Preliminary Evaluation
• OMNIC Mercury TGA software analyzes the complete data set
� Principle component analysis followed by multi-component search
� Guides the interpretation and additional searching
Two Wt Loss Areas
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PC+ABS Characterization – Early Weight Loss
• Extract data from first weight loss region
� 420 – 440 C range �Mixture search using OMNIC Specta software
�Primarily Styrene and related materials
Basic Theory and Instrument Design of FT-IR
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PC+ABS Characterization: Major weight loss
• Extract data from 2nd weight loss region
� 510 - 540 C range
� Direct search in OMNIC provides enough information
� Bisphenol A is the major component
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PC+ABS Characterization – Something’s missing
• Nitrile component predicted by structure
� Not readily pulled out of this complex mixture
� OMNIC Specta - Peak Search comes in handy
� Isocyanic acid – based on nitrile peaks between 2300 & 2200 cm-1
Basic Theory and Instrument Design of FT-IR
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Environmental Stress Cracking is…the premature embrittlement and subsequent cracking of a plastic
due to the simultaneous and synergistic action of stress and
contact with a chemical agent
Environmental Stress Cracking (ESC) Investigation
Jeffrey A. Jansen
Chemical
Plastic
Stress
• Chemical agent permeates into molecular structure →
lower ductility
• Mechanism includes interference with inter-molecular
forces bonding polymer chains
• Reduces energy required for disentanglement/slippage
to occur producing a shift in the preferred mechanism
from yielding
ESC Failure Mechanism:
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Environmental Stress Cracking (ESC) Investigation
Basic Theory and Instrument Design of FT-IR
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Environmental Stress Cracking (ESC) Investigation
• Scrape samples with Diamond ATR:
� Fracture Zone & Intact Area
� Subtract the two spectra followed by Multi-Component Search
�Some clues, but overall unsatisfactory result
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Environmental Stress Cracking (ESC) Investigation
• TGA-IR Analysis:
� Early weight loss area 300 – 360 C
� Extracted spectrum subjected to OMNIC Specta Multi-Component Search
� Identified acetic acid and medium-chain length methyl ester
Basic Theory and Instrument Design of FT-IR
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Environmental Stress Cracking (ESC) Investigation
• TGA-IR Analysis:
� Main weight loss area 390 – 440 C
� Extracted spectrum subjected to OMNIC Specta Multi-Component Search
� Identified an aromatic alcohol, longer-chain length methyl ester
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Poly(ethylene:propylene:diene) (EPDM)
EPDM Characterization
Basic Theory and Instrument Design of FT-IR
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EPDM Characterization
• Paraffinic:
• Naphthenic:
• Aromatic:
EPDM Compounding - Hydrocarbon Plasticizers
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10.88% Plasticizer(1.38mg)
41.26% EPDM(5.25mg)
486°C
189°C
393°C
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1.0
1.2
De
riv. W
eig
ht
(%/°
C)
0
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100
Weig
ht (%
)
0 100 200 300 400 500 600 700
Temperature (°C)
Sample: EPDM RubberSize: 12.7140 mgMethod: Isothermal for
TGARun Date: 10-Oct-2014 15:40Instrument: TGA Q5000 V3.15 Build 263
Universal V4.7A TA Instruments
EPDM Characterization: TGA Analysis - Quantitative
Basic Theory and Instrument Design of FT-IR
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• Plasticizer:
� Paraffinic hydrocarbon
• EPDM Breakdown:
� Unsaturated hydrocarbon
EPDM Characterization: TGA-IR Results – Qualitative
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Textile Example
Basic Theory and Instrument Design of FT-IR
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Diamond ATR Of Fabrics (Pre-TGA)
• Diamond ATR shows difference between fabrics
• Many unique peaks seen below 1000cm-1
NYCO
FR
Ab
so
rba
nce
1000 1500 2000 2500 3000 3500 Wavenumbers (cm-1)
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NYCO TGA-IR Data
Temperature (°C) vs. Time (min)
200
400
600
Te
mp
(C
)
Weight loss (mg) vs. Time (min)
0
2
4
6
Wt.
Lo
ss (
mg
)
Gram-Schmidt (GS)
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0.08
IR I
nte
nsity
5 10 15 20 25 30
Time (minutes)
Temp ramp profile (imported from TGA software)
Weight loss profile (imported from TGA software)
GS shows total IR response as function of time-Peaks in GS correlate to sample weight loss and significant off-gassing detectedFor NYCO, 1 major thermal event was observed at ~26min- Next slide will show IR spectra in that time region
Basic Theory and Instrument Design of FT-IR
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NYCO Evolved Gas Spectra
Linked spectrum at 26.122 min.Linked spectrum at 25.782 min.
Linked spectrum at 26.377 min.Linked spectrum at 26.632 min.
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0.20A
bso
rba
nce
500 1000 1500 2000 2500 3000 3500 Wavenumbers (cm-1)
Linked spectrum at 26.377 min.
0.0085
0.0090
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0.0105
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0.0115
0.0120
0.0125
0.0130
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Ab
so
rba
nce
2900 2950 3000 3050 3100
Wavenumbers (cm-1)
Linked spectrum at 26.377 min.
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Ab
so
rba
nce
850 900 950 1000 1050
Wavenumbers (cm-1)
• Major evolved gas is CO2 at 26min
• Just before CO2 evolution, small signal observed
at ~3000 and ~900cm-1
• See next slide for ID of these peaks
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NYCO – 26.37min Detailed Spectral Analysis9
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96
4
30
16
23
57
211
22
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Ammonia
Linked spectrum at 26.377 min.
Methane
Carbon dioxide
Carbon monoxide
Ab
so
rba
nce
500 1000 1500 2000 2500 3000 3500
Wavenumbers (cm-1)
• 4 components observed including CO2, CO, methane and ammonia
• Spectral overlay shows peaks that match to each species
Basic Theory and Instrument Design of FT-IR
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FR Fabric TGA-IR Data
Temperature (°C) vs. Time (min)
200
400
600Te
mp
(C
)
Weight loss (mg) vs. Time (min)
2
4
6
Wt L
oss (
mg
)
Gram-Schmidt
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0.004
0.006
0.008
0.010
IR I
nte
nsity
5 10 15 20 25 30
Time (minutes)
For FR Fabric, 3 major thermal event was observed at ~16, 26, 31mins- Next slide will show IR spectra in that time region
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FR Fabric Evolved Gas Spectra
Absorbance (Abs)
-0.005
0.000
0.005
Wavenumbers (cm-1)
3800 3600 3400 3200 3000 2800 2600 2400 2200 2000 1800 1600 1400 1200 1000 800 600
Time (minutes)=15.8 min, point #186
Absorbance (Abs)
-0.005
0.000
0.005
Wavenumbers (cm-1)
3800 3600 3400 3200 3000 2800 2600 2400 2200 2000 1800 1600 1400 1200 1000 800 600
Time (minutes)=15.8 min, point #186
Absorbance (Abs)
0.000
0.005
0.010
0.015
0.020
Wavenumbers (cm-1)
3800 3600 3400 3200 3000 2800 2600 2400 2200 2000 1800 1600 1400 1200 1000 800 600
Time (minutes)=31.0 min, point #364
Absorbance (Abs)
0.000
0.005
0.010
0.015
0.020
Wavenumbers (cm-1)
3800 3600 3400 3200 3000 2800 2600 2400 2200 2000 1800 1600 1400 1200 1000 800 600
Time (minutes)=31.0 min, point #364
650°CSpectrum matches to CO2 and CO evolution
345°CSee next slide for library search
Absorbance (Abs)
0.000
0.005
0.010
Wavenumbers (cm-1)
3800 3600 3400 3200 3000 2800 2600 2400 2200 2000 1800 1600 1400 1200 1000 800 600
Time (minutes)=25.7 min, point #302
Absorbance (Abs)
0.000
0.005
0.010
Wavenumbers (cm-1)
3800 3600 3400 3200 3000 2800 2600 2400 2200 2000 1800 1600 1400 1200 1000 800 600
Time (minutes)=25.7 min, point #302
542°CSpectrum matches to CO2 evolution
Basic Theory and Instrument Design of FT-IR
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345°C Linked Spectrum Library Search
• Best match is brominated species
• Species was not seen in NYCO sample
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Conclusions - Deformulation using FT-IR & TGA
• TGA coupled to FT-IR advances capabilities to break materials down
• OMNIC Series, Mercury TGA and OMNIC Specta software provide tools for
analysis of complex mixtures
• Understanding the chemistry of the materials being analyzed is important
Basic Theory and Instrument Design of FT-IR
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Other Applications for Spectroscopy
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•Transmission
• Preferred method for quantitative analysis
• Sample mixed and pressed; good sensitivity
• Attenuated total reflectance (ATR)
• The sample must contact the crystal
• Simple and fast, generally non-destructive
• Diffuse reflectance (DRIFTS)
• Dilute sample in a matrix (like KBr)
• Simple, but requires mixing
• Specular reflectance
• Sample must be reflective or on a mirror
• Signals can be very weak
Add the Right Tools
Basic Theory and Instrument Design of FT-IR
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ATR of Heat Shrink Tubing: Inner Wall
• ATR and OMNIC Specta reveal two components: Polymer and Mg(OH)2
• Mg(OH)2 is used as a flame retardant
Poly(ethylene-co-vinyl acetate) 14 wt. % vinyl acetate
Magnesium Hydroxide
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ATR of Heat Shrink Tubing: Outer Wall
• Outer wall shows something
else
• Subtract outer – inner
• Tyzor 131® is found
• This is a cross-linker
• Causes tubing to shrink!
Basic Theory and Instrument Design of FT-IR
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• Run on Ge ATR
• Multiple
components
• Base polymer
• Silane slip-aid
Black Rubber Gasket