IR-Spectroscopy in Polymer Science
IR-Spectroscopy in Polymer Science
IR-spectroscopy is probably the oldest of the spectroscopic
methods used in polymer science. It is basing of the analysis of
molecular vibrations. It can be subdivided into near-infrared
(NIR), medium-infrared (MIR), and Raman-spectroscopy.
A multitude of techniques are available such as microscopic
techniques, measurements in reflection, at high temperatures and
low temperatures, solid, liquid (and gaseous) samples, on large and
on micro-samples. Even only a few scattered photons can be
determined with high-end CCD-detectors.
In particular in polymer science it is the translational
periodicy of the macromolecules which creates collective motions
and phonons which are detectable by Raman spectroscopy. The
stereochemical, conformational structure, and symmetry properties
give rise for characteristic and specific bands. Starting from only
a few basic concepts a real treasure of chemical and physical
information can be drawn from IR-spectroscopy, see for example Lin
and Brown, who have demonstrated the determination of fifteen
properties of water by NIR.
The simplest application is just the identification of a
material, in particular under the scope of this short course, the
identification of polymer classes. There is a simple flow chart
that can give a crude overview:
In the following there are some examples:
A large amount of spectra of common polymers, special polymers,
additives etc. can be found in literature, see bibliography.
If the thickness of a film or the distance of the windows in a
cuvette is in the appropriate range it can be measured by the
interference pattern that occurs if the surfaces are parallel and
smooth. The light reflected between the parallel surfaces of a film
causes "fringes" in the spectrum which are frequently undesired.
They can be removed by roughening the surface.
Polarization Fourier transform spectroscopy and 2D-spectroscopy
have opened the field of determination of segmental motions and
orientation under the influence of external force fields.
NIR-spectroscopy has recently become an important application of
IR-spectroscopy because it can be used in combination with
light-fibre optics in on-line probe accessories and
high-temperature applications. Besides other applications NIR has
been successfully applied to the diffusion of small molecules in a
polymeric matrix and rheo-optical vibrational spectroscopy to
determine transient structural changes during deformation,
information which can hardly be obtained from other techniques.
Bibliography
Hummel D, Scholl (1968...) Atlas of Polymer Spectroscopy,
Wiley-VCh
Kamowo S, Siesler H W, Ozaki Y, Kawata S (2001)
NIR-Spectroscopy: Principles, Instrumentation, Application
Wiley-VCh, Weinheim
Zerbi G (ed) (1999) Modern Polymer Spectroscopy, Wiley-VCh,
Weinheim
References
Lin J, Brown C W (1993) Appl Spectrosc 47, 1720
Siesler H W, Zebger I, Kulinna C, Okretic S, Shilov S, Hoffmann
U (1998) in Zerbi G (ed) Modern Polymer Spectroscopy, Wiley-VCh,
Weinheim
Noda I, Downrey A E, Marcott C (1998) in Zerbi G (ed) Modern
Polymer Spectroscopy, Wiley-VCh, Weinheim
Siesler H W (1998) in Zerbi G (ed) Modern Polymer Spectroscopy,
Wiley-VCh, Weinheim
_1130433802.ppt
3500-3200 cm-1
1790-1720 cm-1
1610-15901600-1580 cm-11510-1490
1680-1630 cm-1
1550-1530 cm-1
Polyamid
epoxies, polycarbonate, alkyd resins,
polyesters,cellulose-ether, PVCpoly(vinyl acetate), PVC-copoly.,
cellulose ester, PUacryl polymers
Phenol resins, epoxies, aryl polymers
_1130433864.ppt
?
polycarbonate
1610-15901600-1580 cm-11510-1490
1450-1410 cm-1
1100-1000 cm-1
typical pattern of normal PC
typical pattern of PU
C-O-C-ether region
Poly (ether urethane)
? cellulose ester or polyurethane ?
_1130434342.ppt
Intensity, arbitrary units
1/d= 2/n (1/l1 -1/l2)
n = number of minima between two maxima l1 and l2
wave length
_1130435266.ppt
Samples are exposed to external pertubations such
as:temperaturepressurestress
Resolution (the large number of) overlapping NIR bands can be
enhancedand MIR and NIR correlation spectra are very useful for
peak assignement
_1130435321.ppt
general pertubationmechanical, electric, electro-magnetic,
chemical,
Electro-magnetic probeIRX-ray, UV-vis, NMR,
_1130434308.ppt
_1130433838.ppt
1790-1720 cm-1
modified epoxides, polycarbonate, Alkyd resins, polyester,
cellulose ester, cellulose ether, PVC (plast), PVAc, PVC-copolym.,
PU, acrylics
1610-1590 1600-1580 cm-11510-1490
modified epoxides, polycarbonate, Alkyd resins, polyester,
cellulose ester, cellulose ether, PVC (plast)
820-840 cm-1
Modified epoxies, polycarbonate
polycarbonate
_1130433313.ppt
Raman
MIR
NIR
_1130433524.ppt
_1130433252.ppt