| In this paper, triazinyl tetraacrylate(TPTGMA) and phosphate heterocyclic acrylate(PMHPA) were synthesized as flame retardant reactive monomers for UV curable resins. TPTGMA, PMHPA, and pentaerythritol triacrylate(PETA) were blended in different ratios to prepare UV curable phosphorus-nitrogen intumescent flame retardant coatings. The thermal stability, thermal degradation mechanism and limiting oxygen index(LOI) and fire resistance rating were further investigated. The expansion processes of all samples were monitored by a device designed by our laboratory, which results were combined with thermal degradation mechanism to study expansion mechanism. In order to improve the thermal stability of char at high temperature, the UV curable silica sol composite coating was further prepared and was blended with intumescent coating to prepare UV curable intumescent hybrid coatings, which thermal stability and flame retardant properties were investigated. The details of the dissertation are as follows:The TPTGMA was synthesized with cyanuric chloride, 1-Boc-piperazine, and glycidyl methacrylate; PMHPA was synthesized with phosphorus oxychloride, methanol and hydroxypropyl acrylate. The degradation mechanism was further investigated by thermogravimetric analysis and in-situ fourier-transform infrared spectra(FTIR). The ester group in TPTGMA was degradated firstly between 200-290 ℃, and the triazine structure followed between 290-300 ℃. PMHPA firstly degraded to form phosphoric acid and then polycondensed to form poly phosphoric acid(APP) which would catalyse the formation of char.TPTGMA, PMHPA, and PETA were blended in different ratios to prepare UV curable phosphorus-nitrogen intumescent flame retardant coatings. The degradation mechanisms of the cured films were investigated, and the result showed that phosphoric and APP can promote the coating to form char at low temperature. And the amount of residual carbon has been significantly improved to 34.9 % at 600 ℃, due to the formation of phosphorus-nitrogen compounds which has a better stability at high temperature. The expansion processes of the cured films were studied, and the result showed that the char cannot be expanded effectively due to the poor ability of forming char. And the forlula of C4P2N4 has the largest unidirectional expansion. The fire resistance rating of cured films was investigated, and the result showed that the heating curve has the similar trend; the formula of C4P2N4 has the best performance as the temperature of the back of the material was only 358 ℃ which 92 ℃ lower than the blank sample when heated 55 min. The morphology of the cured films after combustion was studied by SEM, and it showed that a uniform and dense honeycomb structure in it. Because of the non-flammable gas could enhance the char to expand, and then the honeycomb pore size increased with higher content of TPTGMA. But the formula of C4P5N1 has a thick pore wall due to the lack of non-flammable gas.The UV curable SiO2 sol were synthesized and blended in different ratios to prepare flame retardant coatings. The degradation mechanism was studied by in-situ FTIR, which showed a similar degradation process, however the amount of residual char was further enhanced due to the good thermal stability of Si-O-Si bond at high temperature. The expansion property was also studied and the result showed that the addition of SiO2 sol has little effect on it. The fire resistance rating was also investigated, and the result showed that the temperature of material was reduced by 119 ℃. |
