M. Elomaa et al., Classification of polymeric materials by evolving factor analysis and principal component analysis of thermochromatographic data, THERMOC ACT, 362(1-2), 2000, pp. 137-144
Thermal decomposition of different polymeric materials was investigated by
thermochromatography (ThGC), a temperature programmed pyrolysis chromatogra
phic method. ThGC produces two-dimensional results; the co-ordinates of whi
ch are the retention time and the pyrolysis temperature at the time of samp
ling. Therefore, principal component analysis (PCA), on results from evolvi
ng factor analysis (EFA) successfully applied would decompose the complete
data of each run into two parts: 'thermograms' and 'chromatograms'. Factor
analysis at this stage compresses the data, making it more convenient for f
urther analysis of the data structure composed of a few dozen of samples. T
he aim of this stage of the data analysis process is to extract 'real therm
ograms' as close as possible to the corresponding 'thermograms' - answering
the question "which products are evolved at each temperature."
Combination of 'chromatograms' and related 'thermograms' obtained on the fi
rst stage were used as characteristic vectors in the further analysis. Sets
of significant 'thermograms'-'chromatograms' were subjected to PCA. Mappin
g of the polymeric samples onto planes defined by factors allows one to ide
ntify clusters as related to different classes of polymers, as well as diff
erent mechanisms of their thermal decomposition. The data was proven to giv
e a very good basis for characterization of the samples by their polymer co
ntent. (C) 2000 Elsevier Science B.V. All rights reserved.