RUBBER-MODIFIED EPOXIES .2. A REACTION-INDUCED PHASE-SEPARATION OBSERVED IN-SITU AND A POSTERIORI WITH DIFFERENT METHODS

The reaction-induced phase separation in epoxy systems modified with r ubber was firstly observed in situ with small angle X-ray scattering ( SAXS), light transmission (LT), light scattering (LS), scanning electr onic microscopy and transmission electronic microscopy techniques. The different observation windows of the SAXS, LT and LS methods allow us to follow the phase separation at two size levels. The selected syste m was bisphenol-A diglycidylether cured with 4,4'-diamino-3,3'-dimethy idicyclohexylmethane, in the presence of 15% wt of epoxy-terminated bu tadiene acrylonitrile random copolymers of different molecular weights . The phase separation inside the particles formed was followed first. Influences of precure temperature, rubber molecular weight, the postc ure, vitrification and gelation on the evolution of the structure insi de the particles are discussed. The real beginning of the phase separa tion is also discussed.