Back to Basics Fundamentals of Polymer Analysis Using Infrared & Raman Spectroscopy

2

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

http://usmad-spt01/common/sidmarcom/antaris/Antaris FT-NIR/Product Photos/MX/MX715113_2M white cutout.jpghttp://usmad-spt01/common/sidmarcom/antaris/Antaris FT-NIR/Product Photos/Antaris II/Antaris715131_2 shdw_M.jpg

3

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:

4

Wavenumbers (cm-1)

Wavelength (m)

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

5

20

30

40

50

60

70

80

90

100

%T

1000 1500 2000 2500 3000 3500 4000 Wavenumbers (cm-1)

C C C C

Stretching Deformation

Bending Twisting

C

+ -

Molecular Vibrations Produce Spectral Fingerprints

6

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

Io=0o

Io=Ro

S D D D D

Aris Associates Ltd2010

7

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

Io=0o

8

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

9

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

10

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

11

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)

0.25

0.30

0.35

0.40

0.45

0.50

0.55

0.60

0.65

0.70

0.75

0.80

0.85

Abso

rban

ce

1320 1330 1340 1350 1360 1370 1380 1390 Wavenumbers (cm-1)

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)

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

0.55

0.60

0.65

0.70

0.75

0.80

0.85

Abs

orba

nce

1000 1500 2000 2500 3000 3500 Wavenumbers (cm-1)

FT-IR can Detect Differences Within Similar Polymers

12

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

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

0.18

0.20

0.22

0.24

0.26

0.28

0.30

0.32

0.34

0.36

Abso

rban

ce

800 900 1000 1100 1200 Wavenumbers (cm-1)

Examples: Vinyl acetate in EVA Ethylene, butene in terpolymer olefins Acrylonitrile in styrene acrylonitrile Tinuvin, Chimassorb UV stabilizers Plasticizers in PVC

13

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

14

Irganox 1076 Quantitative Analysis in Polyethylene

Irganox peak

Polyethylene 2020 cm-1 thickness correction band

Calibration curve Built-in quant analysis report

15

Multi Component Quantitative Analysis in Polyethylene

NIR Spectroscopy

http://usmad-spt01/common/sidmarcom/antaris/Antaris FT-NIR/Product Photos/Antaris II/Antaris715131_2 shdw_M.jpg

17

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

18

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

19

Density of Polyethylene by NIR

20

Ethylene in PP: 2% to 16%

Ethylene/Polypropylene Copolymer Ratio by NIR

9000 cm-1 5000 cm-1

21

At Line Cross-Linked Polyethylene (PEX) by NIR

22

Process Control by Multi-Channel NIR

Antaris MX

http://usmad-spt01/common/sidmarcom/antaris/Antaris FT-NIR/Product Photos/MX/MX715113_2M white cutout.jpg

Raman Spectroscopy

24

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

25

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

R

R H

H

300 400 500 600 700 800 900 1000

Raman shift (cm-1)

For a more in-depth introduction we also have a recorded webinar and other material.

26

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

20

40

60

80

%Tr

ansm

ittan

ce

Raman Spectrum

1

2

3

4

Ram

an In

tens

ity

1000 2000 3000 4000 Wavenumbers (cm-1)

27

Nylon 6 Nylon 6,6

Nylon 6

Nylon 6,6

Raman can Detect Differences Within Similar Polymers

28

Raman is the Ideal Choice for Crystallinity Studies

Raman spectra of crystalline and amorphous polyethylene tere-phthalate (PET) films

29

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

*Subtraction Result:*White PVC 780nm

0

200

400

Int

Anatase

0

20000

40000

60000

Int

Rutile

0

20000

40000

Int

200 400 600 800 Raman shift (cm-1)

30

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

31

Todays Spectroscopic Analysis of Polymers

Simplified by Thousands of spectra in Search libraries Knowledge base allowing the

understanding of polymers in infrared spectroscopy

32

Please Contact Us for More Information

View our website: www.thermoscientific.com/polymers

or

Please feel free to email me: mike.garry@thermofisher.com

http://www.thermoscientific.com/polymersmailto:mike.garry@thermofisher.comhttp://usmad-spt01/common/sidmarcom/antaris/Antaris FT-NIR/Product Photos/Antaris II/Antaris715131_2 shdw_M.jpg

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