Synthesis And Application Of Flame Retarding Benzoxzine Based On Cyclotriphosphazene

Pol ybenzox azines have low-porosit y, near-zero overall shrinkage and ex cellent comprehensive properties, they can be prepared via ring-opening pol ymerization of benzox azine monomers and no small molecules are released during the curing process. Therefore, benzoxazines can be used in the field of copper clad laminate, laminate and refractory matter in stead of phenolic resins. However, pol ybenzoxazines have low thermal stabilit y and low flame retardancy, they can not meet the requirement of high flame retardancy. The composites of cyclotriphosphazene derivatives and benzox azine s have ex cellent flame retardancy, but the cyclotriphosphazene derivatives have poor compatibilit y with benzox azines. This problem will make the cyclotriphosphazene derivativ es eas y to migrate from benzoxazines. The heat resistance, mechanical properties and electrical properties of the composite s t also be affected. So the problems limit the applications of the composites.In this thesis, cycl otriphosphazene was introduced in the molecular structure of benzoxazine. T he benzox azines based on cyclotriphosphazene with two(D3), three(T3), four(F3) and six(H3) functional groups were s ynthesized. The s ynthesis processes of the benzox azine monomers were also optimized. The structures of the benzox azine monomers were characterized by FT-IR and 1H NMR. The thermal properties and flame retardancy of the benzox azine monomers and pol ybenzox azines were characterized b y FT-IR, DSC, TGA, LOI and UL-94. D3, T3, F3 and H3 were s ynthesized b y optimal s ynthesis process es in yi elds of 88.6%, 82.1%, 75.6% and 68.9%. D3, T3, F3 and H3 ex hibited different pol ymerization activities. In the same conditions, H3 was easier to pol ymerize than the others, the initial tempe rature and peak temperature of H3 were 186.0°C and 235.4°C. H4 exhibited higher thermal stabilities and flame retardancy, the 5% and 10% weight-loss temperatures were 344.1°C and 392.7°C, the char yield was up to 64.97% at 800°C. Moreover, the benzoxzines based on clotriphosphazene were easier to pol ymerize than Ba and Bf, the pol ybenzoxzines based on clotriphosphazene exhibited better thermal properties and flame retardancy than PBa and PBf.Based on the above studies, the glass cloth laminates were prepared with H3 and the effects of H 3 on the properties of glass cloth laminate were studied. The results show that the optimum addition content of H3 was 10%, the hot flex ural strength and impact strength were 610 MPa and 98.3 KJ/m2, the dielectric constant and dielectric dissipation factor were 3.97 and 0.0098, the 5% weight-loss temperature was 407.1°C and the char yield was up to 82.61% at 800°C. The laminate s prepared b y H3 had ex cellent composite properties, they can be widel y used in generators, insulating structural parts and transmis sion and distribution equipment which have the requirement of halogen free.