In-line monitoring of the reaction extent of polyurethane during a reactive injection moulding (RIM) process is carried out using fibre-optic near infrared (NIR) spectroscopy. Up to 250 transmission spectra are recorded during the reaction. Univariate and multivariate analysis of transmittance spectra were used to calculate the chemical conversion. A good agreement is observed between first principal component of principal component analysis (PCA), and univariate (Beer—Lambert) results. It is observed that, in this case, the PCA method can provide a good practical estimation of the time-concentration profile during the reaction, without the need of the time-consuming calibration methods. The scores of PC1 are merely linearly correlated to the level of conversion and contain enough information for the quantitative analysis. As expected interactions and hydrogen-bonding play an important role. Hence the spectral region of PCA analysis has to be carefully selected to obtain a good agreement with the Beer—Lambert law. The NIR spectroscopy and the PCA are easy-to-use techniques for on line monitoring of polyurethane reactions and these results open up a low cost effective opportunity for monitoring the fast RIM process.
Andrew, J.J. and Hancewicz, T.M.1998: Rapid analysis of Raman image data using two-way multivariate curve resolution . Applied Spectroscopy52, 797 .
2.
Aries, R.E. , Sellors, J. and Spragg, R.A.1998: In Davies, A.M.C. and Creaser, C.S. , editors. Analytical applications of spectroscopy II. Royal Society of Chemistry .
3.
Aust, J.F. , Booksh, K.S. , Stellman, C.M. , Parnas, R.S. and Myrick, M.L.1997: Precise determination of percent cure of epoxide polymers and composites via fibers-optics raman spectroscopy and multivariate analysis . Applied Spectroscopy. 51, 247 .
4.
Benali, S. , 2001: Etude cinétique et rhéologique des systèmes polyuréthanes — Application au suivi in-situ du procédé RIM. PhD thesis, Institut Nationale des Sciences Appliquées of Lyon .
5.
Benali, S. , Bouchet, J. and Lachenal, G.2004: Chemeorheology: a new design for simultaneous rheological and Fourier transform near infrared analysis . Journal of Near Infrared Spectroscopy12, 5 .
6.
Benali, S. , Bertrand, D. , Dupuy, J. and Lachenal, G.2005: Simultaneous near infrared spectroscopy and dynamic rheological analysis for process monitoring of reactive polymers . Spectroscopy Europe17, 18 .
7.
Bertrand, D. and Dufour, E.2000: La spectroscopie Infrarouge et ses Applications Analytiques . Tec&Doc .
8.
Blanco, M. , Coello, J. , Itturiaga, H. , Maspoch, S. and Villegas, N.1999: Kinetic spectrophotometric determination of hydrocortisone acetate in a pharmaceutical preparation by use of partial least-squares regression . Analyst124, 911—915 .
9.
Brimmer, P. , Monfre, S. and De Thomas, F.A.1992: In Murray, I and Cowes I.A. , editors. Making light work: Advancing NIR spectroscopy. VCH , 554—65.
10.
Chabert, B. , Lachenal, G. and Vinh-Tung, C.1995: Epoxy resins and epoxy blends studied by near infrared spectroscopy . Macromolecular Symposia. 94, 145 .
11.
Chalmer, J.M.2000: Spectroscopy in process analysis. Sheffield Academic Press .
12.
Coello, J. , Fragga, J.M.G. , Iturriaga, H. , Maspoch, S. and Pages, J.1997: Determination of finishing oils in acrylique fibres by near-infrared reflectance spectrometry . Analyst122, 777—81 .
13.
Coleman, M.M. , Lee, K.H. , Skrovanek, D.J. and Painter, P.C.1986: Hydrogen bonding in polymers. 4. Infrared temperature studies of a simple polyurethane . Macromolecules19, 2149—57 .
14.
Corti, P. , Ceramelli, L. , Dreassi, E. and Matti, S.1999: Near infrared transmittance analysis for the assay of solid pharmaceutical dosage forms . Analyst124, 755—58 .
15.
Cuesta, F.S. , Rutan, S.C. , Garcia, M.D.G. and Massart, D.L.1997: Resolution of multicomponent overlaped peak by the orthogonal projection approach, evolving factor analysis and window factor analysis. Chemometrics and Intelligent LaboratorySystem36, 153 .
16.
De Thomas, F.A. , Hall, J.W. and Monfre, S.L.1994: Real-time monitoring of polyurethane production using near-infrared spectroscopy . Talanta41, 425—31 .
17.
Dittmar, K. , Siesler, H.W. and Fresenius, J.1998: Near-infrared light-fiber spectroscopic reaction monitoring of the synthesis of diphenylurethane . Analytical Chemistry362, 109 .
18.
Dreassi, E. , Ceramelli, G. , Fabbri, L. , Vocioni, F. , Bartalini , and Corti, P.1997: Application of near-infrared reflectance spectrometry in the study of atopy. part 1. investigation of skin spectra . Analyst122, 767—70 .
19.
Dupuy, J. , Benali, S. , Maazouz, A. , Lachenal, G. and Bertrand, D.2002: FT-NIR monitoring of a scattering polyurethane manufactured by reaction injection molding (RIM): Univariate and multivariate analysis versus kinetic predictions . Macromolecular Symposia184, 249—60 .
20.
Furusjö, E. and Danielsson, L.G.1998: A method for the determination of reaction mechanisms and rate constants from two-way spectroscopic data . Analytica Chimica Acta373, 83—94 .
21.
Furusjö, E. and Danielsson, L.G.2000: Target testing procedure for determining chemical kinetics from spectroscopic data with absorption shifts and baseline drift. Chemometrics and Intellient LaboratorySystems50, 63—73 .
22.
Hansen, M.G. and Vedula, S.1998: In-line fiber-optic near-infrared spectroscopy: Monitoring of rheological properties in an extrusion process. Part I. Journal of AppliedPolymer Science68, 859 .
23.
Joliffe, I.T.1996: Principal component analysis. Springer Verlab .
24.
Laasonen, M. , Rantanen, J. , HarmiaPulkinen, T. , Michiels, E. , Hiltunen, R. , Räsänen, M. and Vuorela, H.2001: Near infrared reflectance spectroscopy for the fast identification of PVC-based films . Analyst126, 1122—28 .
25.
Lachenal, G. and Osaki, Y.1999: Advantage of near infrared spectroscopy for the analysis of polymers and composites . Macromolecular Symposia141, 283—92 .
26.
Long, S.D. , Dawood, I. , Coates, P.D. and Johnson, A.F.1995: Influence of reaction injection moulding (RIM) processing variables on the mechanical properties of a commercial linear segmented polyamide . Plastics, Rubber and Composits Processing and Applications23, 161 .
Maeda, H. , Osaki, Y. , Tanaka, M. , Hayashi, N. and Kojima, T.1995: Near infrared spectroscopy and chemometrics studies of temperature-dependent spectral variations of water: Relationship between spectral changes and hydrogen bonds . Journal of Near Infrared Spectroscopy3, 191—201 .
29.
Martens, H. and Naes, T.1989: Multivariation calibration. John Wiley & Sons .
30.
Miller, C.E. and Eichinger, B.E.1991: Analysis of reaction-injection-molded polyurethane by near-infrared diffuse reflectance spectroscopy. Journal of AppliedPolymer Science42, 2169 .
31.
Norris, T. , Aldridge, P.K. and Sekulic, S.S.1997: Determination of end-points for polymorph conversions of crystalline organique compounds using on-line near-infrared spectroscopy . Analyst122, 549 .
32.
Priester, R.D. Jr , Mc Clusky, J.J.V. , Cortelk, D.I. , Carleton, P.S. and Porter, J.R.1994: In mold RIM kinetics via mid-infrared fiber optic FT-IR . Journal of Reinforced Plastics and Composites13, 68—86 .
33.
Quinn, A.C. , Gemperline, P.J. , Baker, B. , Zhu, M. and Walker, D.S.1999: Fiber-optic UV/visible composition monitoring for process control of batchreactions. Chemometrics and Intelligent LaboratorySystems45, 214 .
34.
Rey, L. , Galy, J. , Sautereau, H. , Lachenal, G. , Henry, D. and Vial, J.2000: Near-infrared spectroscopy for in situ cure monitoring of dimethacrylate-based networks . Applied Spectroscopy54, 39 .
35.
Sasic, S. , Kita, Y. , Furukawa, T. , Siesler, H.W. and Osaki, Y.2000: Monitoring the melt-extrusion transesterification of ethylenevinylacetate copolymer by self-modeling curve resolution analysis of on-line near-infrared spectra . Analyst125, 2315 .
36.
Sandorfy, C.1979: Overtones and combination tones: Application to the study of molecular associations. In Theophanides, Th. M , editor, Infrared and Raman spectroscopy of biological molecules. D. Reidel , 305—18.
37.
Stevenson, I. , Lachenal, G. and Celette, N.2001: Near-infrared transmittance spectroscopy for radiochemical ageing of EPDM . Analyst126, 2201—206 .
38.
Thomson, M.A. , Melling, P.J. and Stepski, A.M.2001: Real time monitoring of isocyanate chemistry using fibre-optic FTIR probe . Polymer Preprints42, 310—11 .
39.
Wulfert, F. , Kok, W.T. and Smilde, A.K.1998: Influence of temperature on vibrational spectra and consequences for the predictive ability of multivariate models . Analytical Chemistry70, 1761—67 .
