Phase separation during curing reaction in a ternary mixture of Novolac

Poly(ethylene co vinyl acetate) (EVA) and Hexamethylenetetramine (Hexa

curing agent) was investigated by time resolved light scattering.Novolac/EVA system exhibited a Low critical Solution Temperature (LCST) type phase behavior due to H bonding interaction between components.In the early stage of curing

the mixture was in single phase.As the curing reaction proceeded

phase separation took place via spinodal decomposition (SD) induced by the increase in the molecular weight of Novolac.The time variation of qm

the characteristic wavenumber of phase separated structure st which the maximum intensity is located

is quite different from iso-quench thermally-induced SD.q is increased slightly with time attributed to the rapid curing reaction and eventually levelled off with gelling.Cocontinuous phase separated structure was ultimately formed during curing reaction.