Synthesis, Modification And Research Of The Allyl-functional Phthalonitrile And Its Composites

For high temperature resistant thermosetting polymers, phthalonitrile-based polymers, had been widely researched due to excellent thermal and thermo-oxidative stability, superior mechanical property, high char yield, good flame resistance. However,there are many undesirable properties for their application, such as relax reaction activity, high melting temperature, narrow curing window and high price. Therefore, the modification of phthalonitrile was researched.In this article, containing allyl moieties was introduced and a novel allyl-functional bisphthalonitrile monomer DBPA-Ph was designed and synthesized. The synthesis of DBPA-Ph was defined by NMR and FTIR spectroscopy. The differential scanning calorimetry(DSC) and dynamic rheological analysis(DRA) was introduced to characterized the polymerization activity and processing property of DBPA-Ph monomer. The thermal polymerization of allyl moieties and cyano moieties was discovered. The DBPA-Ph performed low melting viscosity and soften temperature.Further, the TGA and DMA was employed to characterized the DBPA-Ph polymers, the result shown excellent glass transition temperature(>350oC) and thermal stability(>430oC).Then, according to further extend the application of DBPA-Ph, two different curing additives cuprous chloride(CuCl) and diamino diphenyl sulfone(DDS) were introduced.The DBPA-Ph/DDS and DBPA-Ph/CuCl blends and prepolymers were studied by DSC for their processing properties, the rheological analysis was employed to research their processing property. The constituter and polymerization reaction mechanism of the prepolymers was characterized by FTIR and the thermal stability of the polymers were studied by TGA. Based on these researches, the GF-reinforced laminates also was prepared and characterized.Next, based on the polymerization properties of the phthalonitrile containing benzoxazine(BA-Ph) and the curing properties of DBPA-Ph, the BA-Ph was employed as curing agent and co-monomer to modify the DBPA-Ph. The DSC and DRA was introduced to characterized the polymerizing properties of DBPA-Ph/BA-Ph system.The DBPA-Ph/BA-Ph system exhibited relatively low melting viscosity and high reaction activity according to the result. The DBPA-Ph/BA-Ph system performed stableand excellent thermal(T5%≥437oC) and thermo- stabilities(T5%≥449oC) which was attributed to the similar stability between DBPA-Ph and BA-Ph polymer. In addition,attributed to the excellent performance of BA-Ph, the DBPA-Ph/BA-Ph/GF composites exhibited improved mechanical property with reduced curing temperature.Finally, N, N’-(4, 4’-methylenediphenyl) dimaleimide(BDM) was introduced to further modify DBPA-Ph. According to the polymerization reaction between DABPA and BDM, the DBPA-Ph/BDM system was prepared and the influence of BDM content was researched. Polymerizing activity and processing property of DBPA-Ph/BDM blends were characterized by DSC and DRA. Based on these researches, the copolymers and composite materials were prepared and studied. The result shown that they have excellent thermal stability(T5%≥410oC) and mechanical properties.