| Abstract
| - TriSilanolPhenyl POSS was chemically incorporated into thermally cured cyanate ester resins. Molecular dispersion plus nanoaggregation (2−200 nm) of POSS moieties was demonstrated by XRD, EDXS, SEM, TEM, and SANS. Lack of POSS extraction confirmed chemical bonding to the matrix. E‘ values from 35 to 350 °C improved with 1−5 wt % POSS loadings.
- Cyanate ester (PT-15, Lonza Corp.) composites containing the blended polyhedral oligomericsilsesquioxane (POSS), TriSilanolPhenyl-POSS (C42H38O12Si7), were prepared containing PT-15/POSS99/1, 97/3, 95/5, 90/10, and 85/15 w/w ratios. The composites were characterized by FT-TR, X-raydiffraction (XRD), small-angle neutron scattering (SANS), scanning electron microscopy (SEM), X-rayenergy dispersive spectroscopy (X-EDS), transmission electron microscopy (TEM), dynamic mechanicalthermal analysis (DMTA), and three-point bending flexural tests. TriSilanolPhenyl-POSS was throughlydispersed into uncured liquid PT-15 resin. After curing, XRD, SANS, and X-EDS measurements wereconsistent with partial molecular dispersion of a portion of the POSS units in the continuous matrixphase while the remainder forms POSS aggregates. Larger aggregates are formed at higher loadings.SANS, SEM, and TEM show that POSS-enriched nanoparticles are present in the PT-15/POSS composites.The storage bending moduli, E‘, and the glass transition temperatures, Tg, of PT-15/POSS 99/1, 97/3,and 95/5 composites are higher than those of the pure PT-15 over the temperature range from 35 to 350°C. The E‘ values for all these composites (except for the 15 wt % POSS sample) are significantlygreater than that of the pure resin at T> Tg. Therefore, small amounts (≤5 wt %) of TriSilanolPhenyl-POSS incorporated into cyanate ester resin PT-15 can improve the storage modulus and the high-temperature properties of these cyanate ester composites versus the pure PT-15 resin. The flexural strengthand flexural modulus are also raised by POSS incorporation.
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