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Infrared Spectroscopic Polymer Identification

This article discusses the use of infrared spectroscopy for identifying different polymers based on their unique infrared absorption patterns. It also explains the determination of layer thickness and intensity using interference patterns. The article provides a comprehensive list of keywords and their corresponding wave numbers for various polymers.

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Infrared Spectroscopic Polymer Identification

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  1. Infrared-spectroscopical Polymer Identification 1790-1720 very strong no yes 1610-1590, 1600-1580 and 1510-1490 1610 –1590, 1600 – 1580 and 1510 - 1490 All numbers have the meaning of wave numbers and are given in cm-1 3500 - 3200 840 - 820 3500 - 3200 1680 - 1630 strong 1450 -1410 sharp strong 1450 - 1410 sharp 1550 - 1530 1100 - 1000 Alkylsilicone, aliphatic hy= drocarbons, Polytetra= Fluorethylene, Thiokol Alkyd-, Polyesters, Cellulose= ether, PVC (plasticized) Acrylics, Polyester Polystyrenes, Arylsilicones, Aryl-alkyl= Silicone Co= polymers Polyamides, amines Nitrocellulose cellophan Cellophan, Alkylcellulose, PVA, PEO Modif. Epoxies Polycarbo= nates Polyvinyl= acetate, PVC-copo= lymers Cellulose= ester Polyure= thane Phenol derivatives, Epoxies PAN, PVC, Polyvinyliden chlorid, POM

  2. Determination of a Layer Thickness Intensity, arbitrary units wave length 1/d= 2/n (1/l1 -1/l2) n = number of minima between two maxima l1and l2

  3. Intererence pattern caused by a PTFE-film

  4. 1790-1720 cm-1 3500-3200 cm-1 1680-1630 cm-1 1550-1530 cm-1 epoxies, polycarbonate,alkyd resins, polyesters, cellulose-ether, PVC poly(vinyl acetate), PVC-copoly., cellulose ester, PU acryl polymers 1610-1590 1600-1580 cm-1 1510-1490 Phenol resins, epoxies, aryl polymers Polyamid

  5. 1610-1590 1600-1580 cm-1 1510-1490 820-840 cm-1 1790-1720cm-1 modified epoxides, polycarbonate, Alkyd resins, polyester, cellulose ester, cellulose ether, PVC (plast), PVAc, PVC-copolym., PU, acrylics modified epoxides, polycarbonate, Alkyd resins, polyester, cellulose ester, cellulose ether, PVC (plast) Modified epoxies, polycarbonate polycarbonate

  6. ? typical pattern of PU polycarbonate typical pattern of normal PC C-O-C-ether region ? cellulose ester or polyurethane ? 1610-1590 1600-1580 cm-1 1510-1490 1100-1000 cm-1 1450-1410 cm-1 Poly (ether urethane)

  7. Infrared Spectroscopy: l = 760 nm….1mm near infrared “quartz-infrared” ~ 10,000…4,000 cm-1 NIR middle infrared “conventional” infrared ~4,000…250 cm-1 far infrared < 250 cm-1 use of quartz cuvettes and light pipes higher order absorptions (lower intensity) liquids can be measured in thicker layers

  8. NIR • Hydrogen-containing groups are dominant • Information is often implicid, coupled vibrations • Not suited for trace analysis • Easy analysis of aqueous solutions • Process-analysis • Use of light-pipes even without cuvette (reflection) • Easy analysis of powders using diffuse reflection • Characterisation of fillers • Determination of water contents in liquids and solids

  9. 4000 cm-1…50 cm-1 fundamental vibrations 4000 cm-1…400 cm-1 fundamental vibrations 12500 cm-1…4000 cm-1 overtones & combinations scattering absorption absorption monochromatic excitation source dispersed polychromatic radiation information from scattered radiation information from absorbed radiation homonuclear functionalities changes in polarizability polar functionalities changes in dipol moment CH/OH/NH functionalities high structural selectivity high structural selectivity low structural selectivity Lambert-Beer-Law Lambert-Beer-Law Iraman~ c sample preparation required (except ATIR) no sample preparation required no sample preparation required sample volume µL sample thickness µm sample volume µL sample thickness µm sample thickness up to cm-range light-fibre optics >100 m light-fiber optics >100 m limited Raman NIR MIR

  10. 2D-Spectroscopy (general scheme) general pertubation mechanical, electric, electro-magnetic, chemical,… dynamic spectrum system Electro-magnetic probe IR X-ray, UV-vis, NMR,… 2D-correlation spectrum

  11. 2 dimensional correlation vibrational spectroscopy Samples are exposed to external pertubations such as: temperature pressure stress Resolution (the large number of) overlapping NIR bands can be enhanced and MIR and NIR correlation spectra are very useful for peak assignement

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