Detailed interpretation of the results of two-dimensional correlation analysis of infrared spectra obtained during isothermal crystallization of isotactic polystyrene and poly(3-hydroxybutyrate)

Two sets of IR spectral data obtained during the isothermal melt-crystalization process of two different polymers are respectively analyzed by two-dimensional (2D) correlation approach. The aim of this study is to inspect this details of the obtained correlation matrices, remove the correlation artifacts and produce reliable 2D correlation results. Particular attention is thus paid to the representation of the correlation data, contour plots and correlation slices. An example of misinterpretation caused by improper thresholding of the asynchronous data is given. Correlation coefficients are also employed to confirm the simplicity of the correlation data. Finally, sample–sample correlation matrix is calculated to additionally confirm that simple two-component systems can immediately be recognized through their correlation pattern.