Preparation And Characterization Of The Halogen-free Poly(Vinyl Alcohol) Fire-retardant Fibers

In recent years, with the technical development and the market demand expansion of the fire-retardant materials, the halogen-free fire-retardant fibers become more and more important. Now the development trend of the fire-retardant materials is toward to halogen-free, low poison, low smoke, durable, low cost as well as environmental friendship. Therefore, besides the efficiency of the fire-retardant materials, the low smoke and the low poison are also the important aspects which lead to the most active research topics in the fire-retardant materials area。Poly(hexamidocyclotriphosphazene) (PHACTPA) and Melamine formaldehyde resin were phosphorus-nitrogen or nitrogen containing fire-retardant materials which is halogen-free and low poison. Certain progress in fire-retardant textiles may be anticipated, if the kind of fire-retardant materials is applied in the fiber or the textile. As the substitutes of fire-retardant materials with halogen, the phosphorus-nitrogen compound with excellent fire-retardant properties attracts much attention in recent year. The phosphorusnitrile compound contains both phosphorus and nitrogen elements, which exhibit good synergistic effect. Its excellent fire-retardant property will open a new field in fire-retardant textile. Melamine formaldehyde resin is another halogen-free fire-retardant material which also has a potential application in fire-retardant fibers.In the review of domestic literatures, no relative research work to the halogen-free poly(vinyl alcohol) fire-retardant fiber has been reported. In this thesis, PVA is used as a fiber-forming material, both HCCTPA and melamine formaldehyde resin as the fire-retardant agents, in order to obtain the fire-retardant PVA fibers with excellent fire-retardant performance.The main objective of this thesis is to prepare new halogen-free fire-retardant PVA fibers. Tow kinds of fire-retardant agent are used. One is PHCCTPA and the other is melamine-formaldehyde resin (MF).In the first part, the fire-retardant poly(hexamidocyclotriphosphazene) (PHACTPA) and PVA fiber containing PHACTPA was prepared and studied. Chlorine in hexachlorocyclotriphosphazene was replaced with ammonia to form HACTPA, and then HACTPA was polymerized in high temperature to gain PHACTPA that was washed by water in order to remove water soluble ammonium chloride. A flame-retardant PVA fiber was produced from a PVA solution containing PHACTPA via a wet spinning process. The reaction mechanism, structure and heat stability of PHACTPA were studied by FT-IR, TG and the flame retardant property of PVA fiber was measured by LOI. The results show that the flame retardant performance of PVA fiber increases with increasing contents of PHACTPA.In the second part, the synthesis of MF resin and the preparation of PVA/MF fire-retardant fiber were studied. The key factor of preparing melamine formaldehyde fiber is obtaining stable spinning solution. A two step procedure was used to prepare spinning solution. The first step was to synthesize the lower viscosity and water-soluble MF resin, and the second step was to mix the resins with PVA solution. The viscosity's stability of MF's solution and the spinning solution of MF/PVA was investigated. Results show that resin's structure at different polymerization step has an effect on the stability of the spinning solution. At the meantime, the mixture status, mixing temperature, ratio of MF to PVA, and storage time, also had an influence on the stability of spinning solution.