Research On The Cure Reaction, Structure And Properties Of Novolac Cyanate Ester

The cyanate ester resins have become important area of research on the high performance resin matrix composites since 1990's. They have many desirable properties including improved dielectric, high mechanical and thermal stability as well as good resistance of flammability, which are all higher than that of phenolic resins, epoxy and BMI resins. They have been widespread used as transparent wave material, structural materials, high temperature adhesives and copper clad lamination(CCL), etc. Furthermore, they have potential applications in a variety of fields such as aeronautics, electronics and military areas. Because of the unique structure, novolac cyanate ester resin(NCE) has the higher thermal and thermolysis properties than that of Bisphenol A cyanate ester, dicyclopentadiene cyanate ester, etc. It is one of the thermal prevention materials, but the research on synthesis and application of NCE is slow, and the study and development is still fresh at home. So it's necessary to do the basic research before application.Via the methods of FTIR, In situ FTIR, DSC, NMR, etc, we studied the curing mechanism, kinetics of cure reaction, curing process of NCE, and found out that the phenol hydroxide group, superfluous phenol, metal ion, or moisture in the NCE resin play an important part during curing process, the pure NCE resin is difficult to cure, and its cure reaction is complex, its total reaction class is 2.8, active energy equals 165.1KJ/mol, and its kinetics equation accord with self-catalyze kinetics model. After experiment and analyse, we know that increasing cure temperature and extending cure time can improve the conversion rate of -OCN group, but the more higher of cure degree, the lower properties the NCE resin has, considering synthesisly, we fix the cure process for 120℃2h+150℃2h+180℃3h+200℃2h+250℃2h。Varieties of thermal analyse and performance test methods were used for the token of NCE structure and properties. And also studied the influence of cure conditions reacting to the structure and properties of NCE, and presented the performances and application prospect of its composite. The result is that NCE resin has excellent thermal and thermolysis properties although its mechanical properties are not good, this is because it contains masses of benzene and triazine. Cure temperature and time also have important influence to the structure and properties of NCE, in order to get a good cured resin with well mechanical and thermolysis properties, a reasonable cure temperature and time should be settled. The mechanical properties of NCE is low, but it has excellent thermal and thermolysis properties, and good resistance of flammability, after modifying and overcoming the difficult problems, NCE will have broad prospect and application areas.