Study On Flame Retardancy Of Cellulose Fibers By Metal Compounds And Their Microcapsules

Cellulose fibers were widely used due to their numerous advantages: renewability, biodegradability, low cost, low density, good mechanical properties. However, some disadvantages limit their industrial applications such as low compatibility with hydrophobic polymer matrix, the flammability and thermal instable. Fibers surface modification could improve the flame retardancy. However, the Viscose fibers spinning should go through concentrated sulfuric acid coagulation bath. In order to improve the flame retardant efficiency, the flame retardant should be resistant to acid.In this study, microcapsule technology was employed to prepare flame retardant microcapsule. Styrene and acrylic acid copolymer as wall material, magnesium oxide, magnesium hydroxide, aluminum hydroxide as core material by in situ emulsion polymerization successfully prepared the flame retardant microcapsule. A large amount of PS chemically bonded on flame retardant surface was confirmed by means of FT-IR, XRD and SEM.ICP results showed that metal ions lost seriously during spinning. The experimental results demonstrated that comparing to the fibers containing untreated metal compounds, metal ions contents of those containing metal compounds encapsulated fibers were found to be significantly improved. This improvement is mostly attributed to the protection from the microcapsule.Combustion behaviors were assessed by using the limiting oxygen index(LOI) and cone calorimetry(CONE). The results indicated that the flame-retardant properties of fibers were enhanced by adding the metal compounds and metal compounds microcapsule. The LOI value of fibers were significantly increased and the heat release rate, the total heat release, the total smoke release values of fibers were obviously decreased.TG analysis indicated that the fibers containing metal oxides produced greater quantites of residues than viscose fibers. By adding the metal compounds, the decomposition temperature of the cellulose fibers decreased obviously. By adding the Mg O and Mg(OH)2, the residues were tighter and denser, and had less cavities on its surface. However, the residues had many crevices on the surface by adding the Al(OH)3.