微晶纤维素的溶解及其阻燃性能

Dissolution and flame retardancy of microcrystalline cellulose

以氯代1-氨甲酰甲基-3-乙烯基咪唑离子液体([CmVIM]Cl)和四丁基氯化铵(TBAC)为溶剂,溶解微晶纤维素(MCC),加入不同阻燃剂三聚氰胺磷酸酯(MP)、聚磷酸铵(APP)、纳米二氧化硅(SiO_(2)),制得了阻燃纤维素复合材料。通过偏光显微镜观察MCC的溶解过程,并利用FTIR、XRD、TGA和SEM对再生MCC的结构、结晶度、热稳定性和形貌变化进行了表征。通过垂直燃烧、极限氧指数(LOI)和热重分析对纤维素复合材料的阻燃性能进行了测试。结果表明,溶解温度为90℃,TBAC用量为[Cm VIM]Cl质量的8%时,MCC的溶解率达6.3%,聚合度降至505;与原MCC相比,再生MCC结晶度指数由74.0%降至46.4%,初始热分解温度由310℃降至262℃,最大失重速率由2.6%/min降至1.4%/min。MCC表面由光滑平整的棒状结构转为凹凸不平的不规则结构。当MP、APP、SiO_(2)质量分数分别为5%、10%和10%时,阻燃纤维素复合材料的极限氧指数提升至33.5%,垂直燃烧等级为Ⅴ-0。

Microcrystalline cellulose(MCC)was dissolved by chlorinated 1-carbamoylmethyl-3-vinyl imidazole ionic liquid([CmVIM]Cl)and tetrabutylammonium chloride(TBAC),and then different flame retardants such as melamine phosphate(MP),ammonium polyphosphate(APP)and nano-silica(SiO2)were added to prepare flame retardant cellulose composites.The dissolution process of MCC was observed by polarizing microscope.The structure,crystallinity,thermal stability and morphology change of regenerated MCC were characterized by FTIR,XRD,TGA and SEM.The flame retardancy of cellulose composites was tested by vertical combustion test,limiting oxygen index(LOI)and thermogravimetric analysis.The results showed that the dissolution temperature was 90℃,TBAC was 8%of[CmVIM]Cl mass,the dissolution rate of MCC was up to 6.3%,and the degree of polymerization was reduced to 505.Compared with those of original MCC,the crystallinity index of regenerated MCC decreased from 74.0%to 46.4%,the initial thermal decomposition temperature decreased from 310℃to 262℃,and the maximum weight loss rate decreased from 2.6%/min to 1.4%/min.The surface of MCC changed from smooth and flat rod structure to uneven irregular structure.The LOI of the flame retardant cellulose composites containing 5%,10%and 10%(mass fraction)of MP,APP and SiO_(2) was up to 33.5%,and the vertical combustion level wasⅤ-0.