Applications of thermoanalytical methods for the study of resinification, curing and thermal degradation of phenolic and epoxy resins are reviewed. The curing properties of PF resins and various epoxy systems~ determined by thermal methods~ are illustrated.Phenolic and epoxy resins are the most common thermosets utilized by the plastics-processing industry. In the cured state they are infusible, insoluble, covalently-cross-linked, thermally stable network polymer structures. The formation of this network structure is responsible for the desirable physical properties which are typical of thermosetting resins over a broad temperature range.Owing to their intractable nature, the thermosetting resins are difficult to study by chemical means. Numerous investigations have shown that thermoanalytical techniques offer valuable tools for the study of the formation, the curing characteristics and the thermal degradation of these resins.The purpose of this paper is to survey the thermoanalytical methods such as differential thermal analysis (DTA), differential scanning calorimetry (DSC), thermogravimetry (TG) and thermomechanical methods, which have been successfully applied to the elucidation of the thermal characteristics of phenolic and epoxy resins.
Phenol-formaldehyde resinsWhen phenol reacts with formaldehyde four major reactions occur: a) addition to give methylol phenols; b) condensation of a methylol phenol and a phenol to give a methylene bridge; c) condensation of two methylol groups to give an ether bridge; d) decomposition of ether bridges to methylene bridges and formaldehyde.The reaction is catalyzed by acids or by bases to give novolacs or resols respectively. The nature of the product is dependent on the type of catalyst and the molar ratio of the reactants. Addition and condensation are exothermic reactions, and therefore thermoanalytical methods are particularly suited for elucidation