| Cyanate ester resin (CE) possesses very low dielectric constant and dielectric loss in a wide temperature and frequency range. It also has balanced heat resistance and processing properties. However, the toughness and modulus of CE are not satisfied. The purpose of this work is to develop a new kind of epoxied-POSS/CE-EP composite with excellent mechanical, thermal and dielectric properties.A novel polyhedral oligomeric silsesquioxane (POSS) containing epoxy groups (EVOS) was synthesized and characterized. The structure, morphology, and thermal, mechanical and dielectric properties of EVOS/CE-EP nanocomposites were studied and investigated with fourier transform infrared spectroscopy(FTIR),x-ray diffraction (XRD),transmission election microscopy (TEM),scanning electron microscopy (SEM),differential scanning calorimetry (DSC), thermal gravimetric analyses (TGA) and. The results from different POSS contents and different ration of epoxy resin and cyanate resin showed that the thermal and mechanical properties of EP-CE/EVOS composites were improved when 1 wt% POSS was introduced. The glass transition temperature for the composites containing 1wt%POSS reached to 208℃, over 20℃higher than the neat EP-CE resin, and the impact strength and tensile strength were also improved at the same time. In addition, the dielectric property was also greatly improved at 1wt%POSS content. The dielectric constant and loss factor were dramatically decreased and the composite possessed very low dielectric constant and loss factor in a wide frequency range. With the content of POSS increasing, a portion of these may aggregated and existed in matrix with free crystals, so the thermal and mechanical properties were decreased.On the basis of above experiments, 10wt%POSS-EP/CE composite modified by MBS showed that the impact and tensile strength were both increased and the glass transition temperature (Tg) increased by 15℃when 1 wt% MBS was introduced. At the same time, the dielectric property decreased slightly.
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