Morphology of poly(ether sulfone)-modified polycyanurates

Polycyanurates prepared from cure of bisphenol A dicysanate (BPADCy) were modified with either hydroxyl-terminated or cyanated poly(ether sulfone)s (as HPES or CPES, respectively) of different molecular weights. With high molecular weight HPES (or CPES), the resulting resin showed a two-phase morphology in contrast to the single-phase morphology generated from the curing reactions of the low molecular weight HPES (or CPES) and BPADCy as observed from optical microscopy. Results from scanning electron microscopy suggests a discrete-continuous fracture surface for the high molecular weight HPES-modified polycyanurate but for the CPES-modified analogue, a blur interface between particle and matrix was observed. However, this blur interface can also be generated if 1 wt% of catalyst system (n-nonylphenol/cobaltic acetylacetonate) was used during cure of mixtures of high molecular weight HPES and BPADCy. This blur interface in the catalyzed system is attributed to the inter-reactions between the hydroxyl termini in HPES and the cyanate groups in BPADCy.