Thermostable cyanate ester resins and POSS‐containing nanocomposites: influence of matrix chemical structure on their properties

Thermostable densely crosslinked cyanate ester resins (CER) with different chemical structures, derived from monomer dicyanate esters of bisphenol E (DCBE), bisphenol A (DCBA), hexafluorobisphenol A (6F‐DCBA) or from cyanated phenol‐formaldehyde oligomer PT‐30, and the nanocomposites based thereon, with 0.01 to 10 wt% epoxycyclohexyl‐functionalized polyhedral oligomeric silsesquioxane (ECH‐POSS), were synthesized and characterized by means of dynamic mechanical analysis, differential scanning calorimetry, far‐infrared, and creep rate spectroscopy techniques. As shown, thermal and mechanical properties increased in a row of matrices prepared from DCBE < DCBA < 6F‐DCBA < PT‐30. Thus, these matrices with T_g = 248, 275, 300, and ~400°C (DMA, 1 Hz), respectively, had dynamic modulus E′ values of 1.8, 2.7–3.0, and 3.6 GPa at 20°C; high rigidity (dynamic modulus of about 1–2 GPa) retained at temperatures up to 200°C for DCBE matrix, 250°C for DCBA and 6F‐DCBA matrices, but up to 380°C for PT‐30‐based matrix. The maximal effects from introducing ECH‐POSS nanoparticles, covalently embedded into CER network, were attained mainly at their ultra‐low contents (<<1 wt%); however, the ECH‐POSS impact decreases in a row of matrices prepared from DCBE > DCBA > 6F‐DCBA > PT‐30. Copyright © 2015 John Wiley & Sons, Ltd.