AN EXPERT-SYSTEM FOR THE INTERPRETATION OF PYROLYSIS MASS-SPECTRA OF CONDENSATION POLYMERS

The PROLOG programming language was used for the construction of the E xpert System (ES) HEPHESTUS used in the interpretation of pyrolysis ma ss spectra of condensation polymers, such as polyamides, polycarbonate s, polyethers, polyesters, polyureas, polyurethanes, polyimides, polys ulphides, polysulfones, polyschiff bases, polysiloxanes and polyphosph agenes. The ES can be applied to Pyrolysis Mass Spectrometry (PyMS) sp ectra of polymers using Electron Impact, Chemical Ionisation or Desorp tion Chemical Ionisation modes. The sample is introduced and pyrolysed directly in the source of the mass spectrometer. The ES knowledge bas e is organised in a tree form, based on polymer structures. The infere nce mechanism uses empirical algorithms and the autocorrelation algori thm to determine important information present in the unknown polymer spectrum. Possible solutions are proposed using the Certainty Factor m odel and based on the rules of the knowledge base. The autocorrelation algorithm, used to determine the repeating unit, gave 57.3% of succes ses and 42.7% not best choices. Among the not best choices the 23.3% w ere failures. For the same purpose, the empirical algorithm gave 68.5% successes and 31.5% not best choices (among them 35.7% were failures) . User interaction improves the ES's performance to propose the correc t polymer (94.4% of the trials were the best choices). (C) 1998 Elsevi er Science B.V.