Study On Flame Retardant Cellulose/SiO₂ Nanocomposite Fiber

Colloidal silica was mixed with viscose in right proportion and made into flame retardant cellulose/silica nanocomposite fibers by wet spinning. Linking state of the interface between nanopaticals and macromolecules was studied; the structure and the properties of flame retardant cellulose/silica nanocomposite fibers were investigated, including spinning technics, thermal stability, flame retardancy and mechanical properties of fibers. The influence on stability of spinning solution was analyzed by studying the structures of colloidal silica and viscose, and then the structure manner of silica and cellulose was discussed. By analyzing viscosity of spinning solution, we found that: viscosity of spinning solution has relation with silica proportion, interaction of silica and cellulose and temperature of solution. By FT-IR and measuring char contents, a good reaction between cellulose and colloidal silica could be concluded. Crystallization of nanocomposites was increased because of the adding of silica particles.By observing the morphology of fibers by TEM and SEM, we found that silica can uniformly disperse into regenerated cellulose in nanometer size, and have a better interface with cellulose. At the same time, we also found that the mechanical properties were greatly changed, compared with viscose fiber.Comparing with viscose fiber by TG/DTG and DSC, we could see that the adding of silica reinforced thermal stability of flame retardant cellulose/silica nanocomposite fibers. In a certain extent, the adding of silica particles changed the thermal pyrolysis and reduced thermal degradation behaviors. We have an extensively research with burning process and its production of heat and smoke of flame retardant cellulose/silica nanocomposite fibers by CONE. The pyrolysis fragments of viscose and flame retardant cellulose/silica nanocomposite fibers were studied by PY-GC-MS. The residua were also studied by SEM. Then we discussed the flame retardant mechanism of SiO₂. The macromolecular chains around silica particles have a high thermal stability. In high temperature, the flame retardant cellulose/silica nanocomposite fibers can form tightly silica char layer, the layer has a function of releasing heat and obstruct. Polysilicic acid can strongly catalyze dehydrate of cellulose, and build up intermoleculars' joinning degree. So the degree of charring can be improved.