Calibration Models for the Vinyl Acetate Concentration in Ethylene-Vinyl Acetate Copolymers and its On-Line Monitoring by Near-Infrared Spectroscopy and Chemometrics: Use of Band Shifts Associated with Variations in the Vinyl Acetate Concentration to Improve the Models

Abstract

The present study investigates calibration models for the vinyl acetate (VA) concentration in ethylene-vinyl acetate (EVA) copolymers and its on-line monitoring by near-infrared (NIR) spectroscopy and chemometrics. The key point in the present study is to make use of band shifts associated with concentration changes in the vinyl acetate (VA) for the improvement of the models. NIR spectra of EVA in melt and solid states were measured by a Fourier transform near-infrared (FT-NIR) on-line monitoring system and a FT-NIR laboratory system. Some of the bands in the NIR spectra for both states show significant shifts with the variations in the VA concentration. The peak shifts induced by the VA concentration changes are larger in the solid-state EVA than those in the melt-state EVA. We have developed calibration models for the VA concentration in the solid-state EVA and investigated how to improve the calibration models. The factor analysis of partial least squares (PLS) regression has suggested that the wavenumber shifts caused by the VA concentration changes affect the calibration models for the VA concentration in EVA. From the analysis, it has been proposed that the wavenumbers in the spectrum of one sample in nine EVA samples (VA concentration range: 0–41.1%) are shifted for the improvement of the calibration models, and the effects of the proposed method have been confirmed by using the PLS calibration models for the VA concentration in the solid EVA samples. As the next step, the effects of the wavenumber shift method have been explored for the calibration models for the VA concentration in the melt-state EVA. After that, the discrimination method using the score plots of PLS and the application sequence for the on-line monitoring to use the proposed wavenumber shift method were studied. The simulation results using the discrimination and wavenumber shift methods have shown that those methods are very effective to improve the predicted values of the calibration models for the online monitoring of the VA concentration in the melt-state EVA.

Keywords

Near-infrared spectroscopy NIR spectroscopy Chemometrics Ethylene-vinyl acetate copolymer EVA On-line monitoring Partial least squares regression PLS Discriminate analysis

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References

Workman

Jr. , J. Near Infrared Spectrosc. 1, 221 (1993).

Siesler

H. W.

, in Near-Infrared Spectroscopy-Principles, Instruments, Applications, Siesler

H. W.

Ozaki

Kawata

and Heise

H. M

, Eds. (Wiley-VCH, Weinheim, 2002), p. 247.

Ozaki

and Amari

, in Spectroscopy in Process Analysis, Chalmers

J. M.

Ed. (Sheffield Academic Press, New York, 2000), p. 53.

Tate

J. D.

Chauvel

Guenard

R. D.

and Harner

, Handbook of Vibrational Spectroscopy, Vol. 4, Chalmers

J. M.

and Griffiths

P. R

, Eds. (John Wiley and Sons, Chichester, 2002), p. 2737.

Kemeny

G. J.

, in Handbook of Near-Infrared Analysis, Burns

D. A.

and Ciurczak

E. W

, Eds. (Marcel Dekker, New York, 2001), p. 729.

Miller

C. E.

, Handbook of Vibrational Spectroscopy, Vol. 4, Chalmers

J. M.

and Griffiths

P. R

, Eds. (John Wiley and Sons, Chichester, 2002), p. 196.

Shimoyama

Hayano

Matsukawa

Inoue

Ninomiya

and Ozaki

, J. Polym. Sci.: Polym. Phys. Ed. 36, 1529 (1998).

Ren

Shimoyama

Ninomiya

Matsukawa

Inoue

Noda

and Ozaki

, Appl. Spectrosc. 53, 919 (1999).

Shimoyama

Ninomiya

Sano

Ozaki

Higashiyama

Watari

and Tomo

, J. Near Infrared Spectrosc. 6, 317 (1998).

10.

Molt

and Ihlbrock

, Fresenius' J. Anal. Chem. 348, 523 (1994).

11.

Moessner

R. C.

, Proc. Control Qual. 2, 237 (1992).

12.

Thomas

Cole

K. C.

Pellerin

and Dumoulin

M. M

, Polym. Mater. Sci. Eng. 72, 19 (1995).

13.

Fischer

Bayer

Eichhorn

K. J.

and Otto

, Fresenius' J. Anal. Chem. 359, 74 (1997).

14.

Farquharson

Arnoudse

P. B.

Wyckoff

M. H.

and Keillor

P. T

, Proc. SPIE-Int. Soc. Opt. Eng. 1172, 164 (1989).

15.

Rohe

Becker

Krey

Nägele

Kölle

and Eisenreich

, J. Near Infrared Spectrosc. 6, 325 (1998).

16.

Nagata

Ohshima

and Tanigaki

, Polym. Eng. Sci. 40, 1843 (2000).

17.

Šašić

Kita

Furukawa

Watari

Siesler

H. W.

and Ozaki

, Analyst (Cambridge, U.K.) 125, 2315 (2000).

18.

Furukawa

Kita

Sasao

Matsukawa

Watari

Šašić

Siesler

H. W.

and Ozaki

, J. Near Infrared Spectrosc. 10, 195 (2002).

19.

Watari

Higashiyama

and Tomo

, 13th European Symposium on Polymer Spectroscopy (ESOPS-13), UK, 20–23 July (1998).

20.

Watari

Higashiyama

Mitsui

Tomo

and Ozaki

, Appl. Spectrosc. 58, 248 (2004).

21.

Watari

and Ozaki

, Appl. Spectrosc. 58, 1210 (2004).

22.

Watari

and Ozaki

, Appl. Spectrosc. 59, 600 (2005).

23.

Mijovic

and Andjelic

, Macromolecules 29, 239 (1996).

24.

Dittmar

and Siesler

H. W

, Fresenius' J. Anal. Chem. 306, 109 (1998).

25.

Hassell

D. C.

and Bowman

E. M

, Anal. Chem. 52, 18A (1998).

26.

Olinga

Winzen

Rehage

and Siesler

H. W

, J. Near Infrared Spectrosc. 7, 223 (2001).

27.

Dumoulin

M. M.

Gendron

and Cole

K. C

, TRIP 4, 109 (1996).

28.

Reahadat

and Balke

S. T

, Appl. Spectrosc. 53, 1309 (1999).

29.

Skaare

L. E.

Klaeboe

and Nielsen

C. J

, Vib. Spectrosc. 3, 23 (1992).

30.

Bains

Reshadat

Lew

Clued

W. R.

Balke

S. T.

and Hall

J. W

, Soc. Plast Eng. Annu. Tech. Conf. 52, 2227 (1994).

31.

Furukawa

Watari

Siesler

H. W.

and Ozaki

, J. Appl. Polym. Sci. 87, 616 (2003).

32.

Khettry

and Hansen

M. G

, Polym. Eng. Sci. 36, 1232 (1996).

33.

Hansen

M. G.

and Vedula

, J. Appl. Polym. Sci. 68, 859 (1998).

34.

Vedula

and Hansen

M. G

, J. Appl. Polym. Sci. 68, 873 (1998).

35.

Swierenga

Wulfertb

De Noord

O. E.

De Weijen

A. P.

Smilde

A. K.

and Buydens

L. M. C

, Anal. Chim. Acta 411, 121 (2000).

36.

Blanco

and Valdés

, J. Near Infrared Spectrosc. 12, 121 (2004).

37.

Thygesen

L. G.

and Lundqvist

S.-O

, J. Near Infrared Spectrosc. 8, 183 (2000).

38.

Alsmeyer

Koß

H-J.

and Marquardt

, Appl. Spectrosc. 58, 975 (2004).

39.

Fearn

, J. Near Infrared Spectrosc. 9, 229 (2001).

40.

Martins

and Naes

, Multivariative Calibration (John Wiley and Sons, Chichester, 1993), p. 347.

41.

Cameron

D. G.

Kauppinen

J. K.

Moffatt

D. J.

and Mantsch

H. H

, Appl. Spectrosc. 36, 245 (1982).

42.

Griffiths

P. R.

and DeHaseth

J. A

, Fourier Transform Infrared Spectrometry (John Wiley and Sons, Chichester, 1993), p. 236.

43.

Strobl

G. R.

and Hagedorn

, J. Polym. Sci.: Polym. Phys. Ed. 16, 1181 (1978).

44.

Ren

Shimoyama

Ninomiya

Matsukawa

Inoue

Noda

and Ozaki

, J. Phys. Chem. B 103, 6475 (1999).