期刊
ANALYTICAL AND BIOANALYTICAL CHEMISTRY
卷 388, 期 5-6, 页码 1207-1213出版社
SPRINGER HEIDELBERG
DOI: 10.1007/s00216-007-1337-5
关键词
FTIR; polyhydroxyalkanoates (PHA); crystallinity; principal-component analysis (PCA); curve fitting; 2D correlation analysis
FTIR spectroscopy has been used to monitor and determine the degree of crystallisation in a sample of polyhydroxybutyrate-co-14%valerate (PHB-co-14%HV). Time series spectra of solution-cast films of the polymer revealed spectral changes attributed to the onset of crystallisation. Curve fitting was used to obtain an absolute measure of crystallinity. Mean centred principal-component analysis (PCA) revealed that 99.9% of the spectral variance could be attributed to factor 1. The loadings plot for factor 1 contained features attributable to crystalline and amorphous phases. These features were opposite in sign, indicating that changes in the spectra with the onset of crystallisation are simultaneous and opposite in direction, i.e. as the crystalline band increases the amorphous band decreases. Cross-peaks in asynchronous 2D correlation maps indicate there are likely to be very minor components that are changing out of phase. The presence of these minor components is supported by examination of the loadings of higher factors in the PCA model. PCA has been shown to be suitable for determining the number of dynamic spectral features and has enabled relative and objective monitoring of crystallisation kinetics.
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