Morphology and thermal behavior of dicyanate ester-polyetherimide semi-IPNS cured at different conditions

A high-temperature thermosetting bisphenol-a dicyanate, BADCy was modified with polyetherimide, PEI, at various compositions. Phase separation and rhe okinetics through curing were studied by optical microscopy, dynamic and is othermal differential scanning calorimetry, and rheological measurements. T he PEI phase separated at the early stages of curing, well before gelation, and did not affect the polycyclotrimerization kinetics. The phase! structu re and thermal properties of the final network were investigated as a funct ion of the PEI content and cure temperature. For this purpose, dynamic mech anical analysis, scanning electron microscopy studies, and thermogravimetri cal analysis were carried out. The morphological changes were interpreted i n terms of a spinodal decomposition mechanism in the composition range stud ied. (C) 2000 John Wiley & Sons, Inc.