19 research outputs found
Spectroscopic studies on curing of novolac epoxy resin—Polyamide and polyamine hardener systems in presence of a polysulphide
381-385Novolac epoxy resins have recently been
reported for inhibition of hydroxy terminated polybutadiene (HTPB) based composite
propellants and their elongation has been improved by the incorporation of some
flexibilizers. In the present investigation, curing behaviour of a novolac epoxy
resin (Dobeckot E4) by hardeners (polyamide EH 411 and polyamine H
758) in conjunction with a polysulphide
flexibilizer has been studied using infrared (IR) spectroscopy. It is observed that
the rate of curing of Dobeckot E4 by hardeners such as hardener EH411 and hardener
H 758, is higher as compared to polysulphide flexibilizer LP-33. Further, rate of
curing of epoxy resin by hardeners such as EH411 and H758 enhances in
the presence of flexibilizer LP-33. The curing
studies by infrared (IR) spectroscopy suggest that hardeners EH41l/H758 react with
epoxy ring of epoxy resin and as a result, epoxy ring opens while curing. Similarly,
-SH group of polysulphide flexibilizer LP-33, reacts with the epoxy ring of resin
and opens it as curing progresses and thus enhances the rate of curing
of epoxy resin in conjunction with hardeners
EH411/H758. This is also supported by the gel time and exotherm peak temperature
data