The development of bicontinuous morphologies in 10 wt% polysulfone (PSu)–epoxy (DGEBA)/anhydride (MTHPA) blends, was followed by optical and scanning electron microscopy. Blends cured at 808C revealed the formation of large epoxy-rich domains surrounded by a PSu-rich matrix, soon after the cloud point. Advancing the cure led to an increase in the volume fraction and the coalescence of epoxyrich domains. A bicontinuous primary morphology was thus generated. A secondary phase separation was observed in both primary phases from the very beginning of the phase-separation process. While spinodal demixing was clearly the mechanism by which the primary morphology was generated, nucleation-growth could be responsible of the secondary phase separation. Postcure steps produced a change in the composition of phases as revealed by DMA, and in the secondary morphology as observed by SEM. A postcure at 1208C led to a single Tg at 1158C with a small shoulder at higher temperatures. A postcure at 2008C led to a Tg at 1088C for the epoxy-rich phase and a Tg at 1378C for the PSu-rich phase. The partial purification of the thermoplastic phase produced a significant enhancement of toughness. KIC was increased from 0.65 MPa m 1/2 for the neat thermoset to 1.10 MPa m 1/2 for the blend postcured at 2008C.
Посилання на статтю:
Development of bicontinuous morphologies in polysulfone–epoxy blends / P.A. Oyanguren, M.J. Galante, K. Andromaque , P.M. Frontini, R.J.J. Williams // Polymer. – 1999. – N 40. – P. 5249–5255.