SYNOPSISNovel epoxy resins of various thiocarbonohydrazones have been synthesized by reacting the aldehyde or ketone derivatives of thiocarbohydrazide with excess of epichlorohydrin. The resins have been characterized by elemental analyses, epoxy equivalents, 'H-NMR and IR spectra, thermal analyses, and viscosity measurements. Curing of the resins has been carried out by mixing with thiocarbohydrazide or ethylenediamine and heating at 80°C for 48 h. A comparison of the thermal stability of the cured resin samples has been made.
SYNOPSISThe curing behavior of a new class of N -N bonded epoxy resins has been analyzed using the simultaneous DTA-TG, dynamic mechanical analysis (DMA) , and thermomechanical analysis (TMA ) techniques. The resin systems, viz, diglycidyl ether of furfuraldehydecarbonohydrazone ( DGFCH ) , diglycidyl ether of furfuraldehydethiocarbonohydrazone (DGFTCH) , and tetraglycidyl ether of vanillinthiocarbonohydrazone (TGVTCH) with the curative, diaminodiphenylmethane (DDM) , taken in stoichiometric amounts have been examined. The curing exotherm could be resolved from the decomposition exotherm qualitatively using DTA-TG analysis. The DMA has been carried out in both the dynamic and isothermal mode to follow the curing process of the systems DGFCH/DDM and TGVTCH/ DDM. The storage modulus (G'), loss modulus (G"), complex viscosity (7) and creep factor (tan 6 ) were measured simultaneously. The crossover point of G' and G", taken as the gelation point in isothermal runs, was determined to obtain time to gelation at that temperature. The isothermal runs a t different temperatures have been used to calculate activation energy of the curing process up to gelation. For the difunctional resin DGFTCH, the activation energy value was found to be 18.7 kcal/mol. The thermomechanical analysis (TMA) has been used to find the glass transition ( Tgo), and melt transition ( T,) temperatures. The cured tetrafunctional TGVTCH /DDM system as expected, has higher T, than those of the two difunctional resin systems.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.