Viscoelastic effects on the phase separation in thermoplastics modified cyanate ester resin

A high temperature thermosetting bisphenol-A dicyanate, BADCy was blended with a thermoplastic poly(ether imide) (PEI). The phase separation behavior of the blend was investigated by scanning electron microscopy (SEM) and time resolved light scattering (TRLS). It was found by SEM that the blend with 20 and 25 wt% PEI had a phase inversion structure. The results of TRLS displayed clearly that the phase separation took place according to a spinodal decomposition (SD) mechanism and the evolution of both scattering vector qm and the maximum scattering intensity Im followed Maxwell-type relaxation equation. The temperature-dependent relaxation time τ for the blends can be described by the Williams–Landel–Ferry equation. It demonstrated experimentally that the phase separation behaviors in PEI/BADCy blends were affected by viscoelastic effect.