Search

The aim of this research was the detailed analysis and estimation of CER oligomer‐based nanocomposites for applications under extreme high temperature conditions. Thermostable nanocomposites based on cross‐linked cyanate ester resin (CER), derived from PRIMASET PT‐30 multi‐functional oligomer and doped by 0.025wt% to 10wt% epoxycyclohexyl‐functionalized polyhedral oligomeric silsesquioxane (ECH‐POSS) nanoparticles, were synthesized and characterized using TEM, mid‐, and far‐IR spectroscopy, and by DMA, DSC, CRS, and TGA techniques. At nanoparticles contents less than 1wt%, basically their molecular level dispersion in the matrix is suggested, whereas their clusters of about 20 to 30 nm in diameter were observed at 2wt% and 10wt% ECH‐POSS. In correlation with the results of structural analysis, the ambivalent influence of the nanoparticles, depending on their content, on the dynamics and properties of nanocomposites was revealed. The "constrained dynamics" effects caused by post‐curing and covalent embedding ECH‐POSS units into the matrix were registered by DMA, far‐IR spectroscopy and CRS. Highly cooperative glass transition with Tg ≈ 400°C (DMA, 1 Hz) was observed, and at the limit total suppression of glass transition could be achieved. The obvious superiority of the studied nanocomposites over the CER nanocomposites synthesized from monomeric dicyanate ester of bisphenols, especially at high temperatures, was shown. [ABSTRACT FROM AUTHOR]

We have fabricated amorphous polymer composites with ultralow silica contents (e.g., 0.1 wt %), without nano- or microclusters but with silica units distributed quasi-regularly within the polymer network matrix. This fact and other data obtained imply the existence of subnanometer-sized silica nodes (SNSSN) only in this case which are connected covalently with the matrix, i.e., the formation of the hybrid subnanocomposites . In this work, the densely cross-linked Cyanate Ester Resins (CER)-based composites with 0.1–10 wt % silica, introduced by a sol-gel method, were synthesized and investigated by HAADF STEM, EDXS, far-IR spectroscopy, DMA and DSC. The obtained subnanocomposites manifest an extremely high “constrained dynamics” effect and superiority in thermal and mechanical properties compared to those of the nanocomposites with higher silica contents. [ABSTRACT FROM AUTHOR]