SEQUENCE OF PHENOLIC UNITS IN PHENOL FORMALDEHYDE POLYCONDENSATES STUDIED BY PYROLYSIS-GAS CHROMATOGRAPHY MASS-SPECTROMETRY

Pyrolysis-gas chromatographic/mass spectrometric (Py-GC/MS) analyses of phenol-, o-cresol-, m-cresol- and p-cresol formaldehyde novolacs performed at 600-degrees-C are presented. The pyrolysis product distribution was correlated with the structural characteristics of the sample deduced from the distribution of dimer and trimer isomers analysed after silylation. The domination of ortho to para methylene junctions of the phenolic units in the structure of the novolacs is reflected in the preference of the production of dimers of similar linkages under pyrolysis. At the same time the distribution of phenols in the pyrolysate reveals the frequency of terminal phenolic units coupled at different positions by the methylene bridge, moreover it shows the preference of joining positions of the phenols inside the chain in the case of phenol- and m-cresol-formaldehyde novolacs.