Characterization of the Cross-Linked Structure of Cured Novolac Resins with Hexamethylenetetramine by Pyrolysis-Gas Chromatography

Pyrolysis-gas chromatography (PyGC) was used for cured novolac resins with hexamethylenetetramine (HMTA) in order to investigate the cross-linked structure. Several kinds of novolac fractions having various molecular weights and ortho ratios of methylene linkage (OR) were pyrolyzed at 670 degrees C. Phenol and methylphenols which were pyrolysis products were determined quantitatively using a gas chromatograph. There was a correlation between the composition of pyrolysis products and the structure of resin and the formulae to estimate OR and M/P from PyGC data were obtained. Based on PyGC analyses of cured high-ortho novolac or random novolac resins with HMTA by using the obtained formulae, it was shown that random novolac efficiently reacted with HMTA than high-ortho novolac.