Preparation And Properties Of Silazane/Phthalonitrile Hybride Resin

As an organosilicon compound polymer, the silazane has Si-N structure inthe molecular structure and has many excellent physical and chemical properties.Phthalonitrile is a high performance thermoset resin which possesses excellenthigh-temperature properature properties and superior mechanical properties. Thedissertation is devoted to combine the silazane and phthalonitrile by thephysically blend or structural chemical modification method and the quartz fiberreinforced composite was prepared. The main works are as follows:Polysilazane resin was modified by the phthalonitrile resin and PSN1/mPNquartz fibre composites were prepared. The reaction activities and properties ofhybrid resins were investigated by rheometer, IR, TGA, mechanics properties anddielectric properties tester. The results indicated that copolymerization reactiontook place between mPN and PSN1, and with the increase of mPN in the reactionsystem, the thermal properties decrease and the mechanical properties increasedof the hybrid resins. When the amount of mPN was40%, the thermal propertywas close to PSN1and the residue weight reached to82%under N2atmosphereat1000℃. The flexural strength of the hybrid resin composite was183MPa and156MPa at450℃,500℃, improved36%and38%compared with the purePSN1composites, respectively. Meanwhile, the hybrid resin composite possessedexcellent dielectric properties with dielectric constant below2.23and dielectricloss below0.012in the temperature range of room temperature to500℃andfrequency range between1and12GHz.A series of silicon-containing self-catalyzed phthalonitrile derivatives hadbeen successfully synthesized by the reaction of chlorosilane with4-(4-aminophenoxy)phthalonitrile (APN). The chemical structure of the silicon-containing monomers has been confirmed by spectroscopic techniques. The newphthalonitrile monomers have low melting point (60-80℃) and are soluble in common solvents. DSC reveals that they can be thermally polymerized innitrogen atmosphere without any catalysts. The thermal properties of the curedsilicon-containing monomers were characterized by TGA and DMA. Comparedto APN,5%weight loss (T5%) and char yield at1000℃of which are519℃and75.1%in nitrogen, and507℃and1.8%in air, respectively, the newsilicon-containing phthalonitriles exhibit improved thermal stability with T5%ranged from535to570℃in nitrogen,543to562℃in air atmosphere, andchar yields at1000℃ranged from80.2%to82.6%in nitrogen. The DMAmeasurement revealed that the composites of the resins did not exhibit a glasstransition process upon heating to450℃.