Development of bicontinuous morphologies in polysulfone?epoxy blends

P.A. OYANGUREN; M.J. GALANTE; K. ANDROMAQUE ; K. ANDROMAQUE; P. M. FRONTINI,; R. WILLIAMS

POLYMER

ELSEVIER SCI LTD

Lugar: Amsterdam; Año: 1999 p. 5249 - 5255

0032-3861

The development of bicontinuous morphologies in 10 wt% polysulfone (PSu)?epoxy (DGEBA)/anhydride (MTHPA) blends, wasfollowed by optical and scanning electron microscopy. Blends cured at 808C revealed the formation of large epoxy-rich domains surroundedby a PSu-rich matrix, soon after the cloud point. Advancing the cure led to an increase in the volume fraction and the coalescence of epoxyrichdomains. A bicontinuous primary morphology was thus generated. A secondary phase separation was observed in both primary phasesfrom the very beginning of the phase-separation process. While spinodal demixing was clearly the mechanism by which the primarymorphology was generated, nucleation-growth could be responsible of the secondary phase separation. Postcure steps produced a changein the composition of phases as revealed by DMA, and in the secondary morphology as observed by SEM. A postcure at 1208C led to a singleTg 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 1378Cfor the PSu-rich phase. The partial purification of the thermoplastic phase produced a significant enhancement of toughness. KIC wasincreased from 0.65 MPa m1/2 for the neat thermoset to 1.10 MPa m1/2 for the blend postcured at 2008C.