High glass transition temperature bismaleimide-triazine resins based on soluble amorphous bismaleimide monomer

Propargyloligosilazane matrixed composite for high temperature material combining polymer and ceramic properties

A new single-phased thermosetting resin (propargyloligosilazane, POSZ) was prepared through Hofmann alkylation of oligosilazane with propargylbromide; the propargyl content in POSZ was controlled by monitoring the amount of propargylbromide in synthesis. The characterizations showed that POSZ has ideal rheology during material processing, the thermal curing temperature could be lowered when isocyanate was used as crosslinking agent, and the thermally cured POSZ can be pyrolyzed into anti-oxidative ceramic at a high yield of >70%. For POSZ-matrixed carbon-fabric laminate composite, it possessed high mechanical properties and retained the original shape with the increase of temperature as high as 800 °C. The POSZ-matrixed laminate has the mechanical properties combining polymer character at room temperature and ceramic character at high temperature, and it will find many prospective high temperature applications in need of polymer and ceramic properties simultaneously.

Amino Functionalization of Reduced Graphene Oxide/Tungsten Disulfide Hybrids and Their Bismaleimide Composites with Enhanced Mechanical Properties

A novel graphene-based nanocomposite particles (NH₂-rGO/WS₂), composed of reduced graphene oxide (rGO) and tungsten disulfide (WS₂) grafted with active amino groups (NH₂-rGO/WS₂), was successfully synthesized by an effective and facile method. NH₂-rGO/WS₂ nanoparticles were then used to fabricate new bismaleimide (BMI) composites (NH₂-rGO/WS₂/BMI) via a casting method. The results demonstrated that a suitable amount of NH₂-rGO/WS₂ nanoparticles significantly improved the mechanical properties of the BMI resin. When the loading of NH₂-rGO/WS₂ was only 0.6 wt %, the impact and flexural strength of the composites increased by 91.3% and 62.6%, respectively, compared to the neat BMI resin. Rare studies have reported such tremendous enhancements on the mechanical properties of the BMI resin with trace amounts of fillers. This is attributable to the unique layered structure of NH₂-rGO/WS₂ nanoparticles, fine interfacial adhesion, and uniform dispersion of NH₂-rGO/WS₂ in the BMI resin. Besides, the thermal gravimetrical analysis (TGA) revealed that the addition of NH₂-rGO/WS₂ could also improve the stability of the composites.

Oligosilylarylnitrile: The Thermoresistant Thermosetting Resin with High Comprehensive Properties

One of the highest thermoresistant thermosetting resins ever studied so far, oligosilylarylnitrile resin, was investigated first in this study. Oligosilylarylnitrile was synthesized by lithium-reduced Wurtz-Fittig condensation reaction, and the prepared viscous resin exhibited moderate rheological behaviors while heated purely or together with 20% polysilazane as a cross-linking agent. The thermal curing temperatures were found by differential scanning calorimetry at 268 °C (pure) and 158 °C (with the polysilazane cross-linking agent), which is comparably close to that of polysilylarylacetylene resin (normally at 220-250 °C) but much lower than those of polyimide and phthalonitrile resins (normally >300 °C), indicating the admirable material processability of oligosilylnitrile. The cured oligosilylarylnitrile resins have extremely high thermal resistance, indicated by the results of thermogravimetric analysis (the mass residue at 800 °C is >90% under N₂) and dynamic mechanical analysis (the glass-transition temperature is >420 °C). The mechanical property of the oligosilylarylnitrile-matrixed silica-cloth reinforced laminate is comparably close to those of polyimide and phthalonitrile but much higher than that of polysilylarylacetylene, indicating the enviable thermal and mechanical properties of oligosilylnitrile. Thus, among the high-temperature resins ever studied so far, the oligosilylarylnitrile resin was found to have the almost best comprehensive characteristics of processability and properties.