Effect On The Thermal Stability And Viscose Fiber Combustion Properties Of Transition Metal Oxides

Viscose fiber is the most widely used fiber made from natural cellulose originating from cotton, hemp, wood and straw, etc. It is featured by comfortable wearing, good dying and absorpotion properties, biodegradability. But it burns easily for its limited oxygen index (LOI) being only20, so it is a necessity to modify viscose fiber with flame retardancy.In the thesis, several kinds of transition metal oxides were selected to prepare complex fibers by wet-spinning methods. The combustion behavior and flammability of viscose fiber, cellulose/ZnO fiber, cellulose/ZrO2fiber and cellulose/TiO2fiber were assessed using inductively coupled plasma (ICP), scanning electron microscope (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), LOI and cone calorimeter test.ICP and XRD results showed that ZnO lost seriously during spinning due to the formation of ZnSO4·6H2O in the cellulose/ZnO fiber. The thermal decomposition of zinc salt produces ZnO. Because the chemical property of ZrO2, TiO2is stable, they does not change in the process of wet spinning. TG analysis indicated that the fibers containing transition metal oxides produced greater quantites of residues than viscose fiber.The decomposition temperature of the cellulose/ZnO fiber decreased obviously, the residues were tighter and denser, and had less cavities on its surface. The decomposition temperature of the cellulose/TiO2fiber decreased obviously too, but the residues had many crevices on the surface and were easily oxidized. ZrO2does not have much effect on thermal-decomposition of the fiber, the residues contain large amounts of Zirconia.LOI values were used to evaluate the flame-retardant properties of the fibers. The results showed that the cellulose/ZnO fiber had good flame-retardant properties. Cone calorimetry indicated that the heat release rate and total heat release values of fibers containing transition metal oxides were significantly less than those of viscose fibers. ZnO and TiO2showed better smoke-suppression effect. On the other hand, the solid additives brought about increasing formation of CO, leading to the increase of smoke toxicity.