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A kinetic study of the oxidative degradation of phenol-formaldehyde polycondensates using infrared spectroscopy
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1963
Year
EngineeringAdjacent Phenol RingsDegradation ReactionOrganic ChemistryPhenol-formaldehyde RatiosChemistryPolyphenolicsKinetic StudyPolymersChemical EngineeringPlastic DegradationRedox ChemistryPolymer ChemistryPhotochemistryInfrared SpectroscopyBenzophenone LinkagePhotodegradationOrganic Material ChemistryPhenol-formaldehyde PolycondensatesChemical Kinetics
The oxidative degradation of cured phenolic resin has been investigated by continuous monitoring of the infrared spectral changes occurring in the solid phase at temperatures between 140 and 220°C. The postulated mechanism for oxidation of methylene bridge linkages activated by adjacent phenol rings has been substantiated on the basis of rate differences observed on changing the phenol-formaldehyde ratios. This process is general as shown by a proportional decrease in oxidation on examination of a typical bisphenol-formaldehyde polycondensate. The formation of quinoid species and their oxidation to acid and quinone fragments are in good agreement with the kinetic data and the mechanism proposed earlier. Attempts to polarographically detect differences in reactivity due to the position of the benzophenone linkage and the phenolic hydroxyl indicated that no major observable differences could be observed in the solid phase. The apparent initial activation energy of oxidation is of the order of 19 kcal.