Polymers, additives, surfactants and their mixtures: Computer-based search with special FTIR libraries

This investigation was done with a PC of 850 MB/33 MHz, Windows 3.1 and the SPECTACLE program of LabControl/Cologne. The libraries contained standardized FTIR spectra of 3061 defined polymers, 530 industrial polymers and resins, 1969 additives (pigments, stabilizers, plasticizers etc.) 1190 surfactants and 1614 monomers, pyrolyzates and educts. For searches, the data density was reduced to 4/cm. Similarity search with standardized full spectra yields quantitative dissimilarity figures; it allows an experimental definition of identify. The derivative functions 3 and 4 of LOWRY and HUPPLER increase the gap between identical and similar spectra. With the LH2 algorithm spectra are defined as identical if their dissimilarity val;es are within 10(3). Since all organic matter has some spectral similarity the LH2 dissimilarity for organics will not go far beyond 10(5). - The quality of IR preparation has a strong impact on search results. If a library contains spectra with false-light, CHRISTIANSEN effect, high noise or other artefacts, peak search yields better results than similarity search with full spectra, Multicomponent systems can be searched successfully for their constituents with an algorithm combining peak and similarity searches. This algorithm is superior to all other algorithms if a library contains spectra with artefacts.