P-aminobenzoic acid/cyclohexanon/formaldehyde resins as hardner for epoxy resins. Synthesis and characterization

New formaldehyde resins with p-aminobenzoic acid and cyclohexanone that contain functional groups in structure were obtained at various molar ratios under acid catalysis. Mixture of DMF/toluene was used as reaction medium and as carrier for aqueous condensation. These polymers were characterized by IR, H-1-NMR spectroscopy and elemental analysis. The obtained resins have low molecular weight and are soluble in medium and high polar solvents. Using these formaldehyde resins as hardener, the curing behaviours of some epoxy resins were investigated. The activation energies and the curing temperatures were studied by DSC using Ozawa and Kissinger methods. The thermal properties of cured product were also investigated.