Spectral and thermal analysis of aromatic diamines and anhydrides cured chalcone moiety containing epoxy resin of (2E,6E)-bis(4-hydroxybenzylidene)cyclohexanone

Chalcone moiety containing epoxy resin of (2E,6E)-bis(4-hydroxybenzylidene)cyclohexanone (EBHBC) was cured at 150 degrees C by using 4,4 '-dimethyldiphenylmethane (DDM), 4,4 '-diaminodiphenylsulphone (DDS), 4,4 '-diaminodiphenylether (DDE), p-phenylenediamine (PDA), 1,2,3,6-tetrahydrophthalicanhydride (THPA), maleic anhydride (MAH) and pyromelliticdianhydride (PMDA). Aromatic diamines cured EBHBC took little longer gel formation time than those of anhydrides cured EBHBC. Sol-gel analysis of cured resins was carried out in DMF at room temperature. Aromatic diamines and anhydrides cured EBHBC showed 4.2-15.6% and 2.4-7.5% sol fractions; and 84.4-95.8% and 92.5-97.6% gel fractions, respectively. DSC exothermic transitions supported curing of EBHBC, while endothermic transition supported decomposition of cured resin as supported by TGA. Aromatic diamines and anhydrides cured EBHBC are thermally stable up to 270-305 degrees C and 162-316 degrees C, respectively, and followed single-step degradation reactions except EBHBC-MAH. Aromatic diamines (35-58%) and anhydrides (46-56%) cured EBHBC showed considerably large residues at 700-800 degrees C. Aromatic diamines and anhydrides cured EBHBC showed, respectively, 30-52% and 32-41% residues at 700-800 degrees C. Cured EBHBC resins followed either apparently first order or one and half order degradation kinetics. Cured EBHBC resins showed different E-a and A values indicating inherent structural effect of different hardeners used.

Automated summary

The chalcone moiety epoxy resin EBHBC was cured using different hardeners, resulting in different gel and sol fractions in sol-gel analysis. The cured resins showed variations in thermal stability, residues, and degradation kinetics depending on the aromatic diamines and anhydrides used in the curing process.