| Basalt(BS)is a new green material with abundant reserves in the world,and it is important to improve the use of basalt.A green degradable polyvinyl alcohol/chitosan as film-forming substance and basalt as filler can be used to prepare a wood basalt flame retardant surface coating.In order to further improve the flame retardant performance of the coating,a basalt/aluminium hypophosphite(AHP)flame retardant was added,and a basalt/aluminium hypophosphite composite flame retardant coating was prepared by changing the intermixing ratio of AHP and BS,but the smoke suppression performance of the coating was poor;therefore,the surface modification of basalt was carried out on this basis to prepare a flame retardant smoke suppression hydrogel coating.The main research contents and results are as follows.(1)The effects on the structure and morphology,thermal weight properties,flame retardant properties,water resistance and other physical and mechanical properties of the coatings were investigated when comparing the flame retardant coatings prepared by adding different mass fractions of BS scales.It was concluded that when BS was added at 10 wt%(PP10 group),the BS was more uniformly dispersed in the coating and the maximum thermal weight loss rate of the coating was significantly lower than that of the coating without the addition of basalt.The pk-HRR and THR as well as the maximum heat release temperature of the coated wood were significantly reduced,with the pk-HRRR and THR of the PP10 group decreased by 66%and 17%compared with the uncoated wood,and the temperature at maximum heat release was shifted back by 78.5℃.Moreover,the coating reduced the water absorption of the wood,and the adhesion and pencil hardness properties of the coating were excellent.(2)The effects of adding different mass fractions of BS scales on the structure and morphology,thermal weight properties,flame retardant properties,water resistance and physical and mechanical properties of the coatings were investigated and compared.It was concluded that when BS was added at 10 wt%(PP10),the BS was more uniformly dispersed in the coating,the maximum thermal weight loss rate of the coating was significantly lower than that of the coating without the addition of basalt,and the decomposition of the third stage of the coating was delayed,and the residual carbon rate was greatly improved,in which the residual carbon rate reached 35.39%.The pk-HRR and THR of the coated wood and the maximum heat release temperature were significantly reduced,with the pk-HRR and THR of the PP10 group decreasing by 66%and 17%compared to the pure wood,and the temperature at maximum heat release was shifted back by 78.5℃.However,the total smoke emission of coated wood was significantly higher than that of wood.(3)In order to improve the flame retardant and smoke suppressing properties of the coatings,the basalt was modified by surface modification and co-precipitation method,and aluminum phytate,nickel phytate and zinc phytate were deposited on the surface of basalt to investigate the effects of different modification methods on the thermogravimetric properties,flame retardant and smoke suppressing properties and physical and mechanical properties of the coating.The results of SEM and FTIR analysis showed that the phytate metal salts were successfully deposited on the surface of basalt.Among them,the best performance was achieved when phytate nickel(BS-PA-Ni)was deposited on the BS surface;the thermogravimetric results showed that the residual carbon rate was significantly increased by the addition of modified basalt and aluminum hypophosphite,where the residual carbon rate of the control group coating was 3.12%,while the BS-PA-Ni group coating was 27.27%,and the thermal stability of the coating was improved.The pk-HRR,THR and TSP of the BS-PA-Ni hydrogel coated wood were reduced by 64.2%,32.7%and 51.3%,respectively,compared with the uncoated ones,and achieved V-0 rating in UL-94 test. |
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