Preparation And Properties Of Modified Polyvinyl Alcohol Fiber By Gel Spinning

Poly(vinyl alcohol)(PVA) is a flexible-chain polymer with hydroxyl on its side groups, and is environmentally friendly, good acid and alkali resistance, and good weather ability, with a broad range of industrial and technical applications. Conventional PVA fiber named vinylon that was used in the clothing industry a large number of applications,before the 1970 s. With the development of polyester is more suitable for the garment sector, vinylon was phased out. High strength and high modulus PVA fiber has many special characters, such as good weather resistance, good substrate affinity. The theoretic strength and modulus of PVA are 210 and 900 c N/dtex, while the highest strength and modulus of the commercial PVA are just 21.1c N/dtex and 600 c N/dtex, so it has larger development prospects. In this thesis, the gel spinning process PVA was investigated, and two kind of polyvinyl alcohol Modified fibers was prepared.Firstly, effect of coagulation bath temperature, jet-draw, air pre-draw and hot-draw conditions on structures and properties of PVA fibers by gel spinning was investigated. The results indicate that coagulation bath temperature has a great influence on performance of fiber, PVA fiber can be solidified in the ethanol at 25?,but it has poor mechanical properties,tensile properties and is milk white. When the coagulation bath temperature is below 10?, the appearance of the as-spun fiber has little difference, but with lower coagulation bath temperature, the capacity of draw ability has a small increases. Jet-draw is 0, the PVA fiber has a maximum draw ability. The PVA fiber with air pre-draw then hot draw has bigger draw ratio that PVA fiber only hot draw. Hot draw ratio decrease with air pre-draw ratio increases, and the total draw ratio increases firstly and then decreases at different air pre-stretching. When the air pre-stretching ratio is 3 times, the PVA fiber has maximum total draw ratio, the maximum total draw ratio is 30 times. Temperature has great influence on hot draw. In the range of 180? to 220?, the heat draw ratio was increased after the first downward trend with increasing temperature, and PVA fiber has the maximum total draw ratio at 200?. When the temperature exceeds 210? PVA fibers will be yellow with oxy-genated. Strength and modulus PVA fibers was positively correlated with the total draw ratio. PVA fiber with 3 times of air pre-stretching first, and then draw 10 times in the 200?, that has the highest strength and modulus, strength and modulus 13.4c N/dtex and 103 c N/dtex, respectively.Secondly, PVA fiber modified(I/PVA) by I2 /KI solution was preparated. Effect of concentration of I2/KI solution, jet-draw, air pre-draw and hot-draw conditions on structures and properties of I/PVA fibers by gel spinning was investigated. The results show that intermolecular hydrogen effect of modified PVA fiber becomes weak, draw ability of the modified fibers is larger,compare with PVA fiber. But Thermal stability is worse than PVA fiber. In the range of 0.01mol/L to 0.2 mol/L of the concentration of I2/KI solution, the draw ratio of I/PVA was increased after the first downward trend with increasing concentration, and I/PVA fiber has the maximum total draw ratio at 0.1 mol/L I2/KI solution, the maximum total draw ratio is 36, which compared with neat PVA fiber, increased by 20%. 3 times Air pre-draw ratio is best for I-PVA fiber. The best hot draw temperature of I-PVA is 150? that is lower, compared with PVA fiber that is 200?. Both fibers have similar crystallinity and Like crystals, but the Orientation of I-PVA is higher.Finally, the graphene oxide(GO) and PVA blend fiber(GO/PVA) was obtained. Effect of content of GO, jet-draw, air pre-draw and hot-draw conditions on structures and properties of GO/PVA fibers by gel spinning was investigated. The results show that the GO-PVA fibers with 0.1% of GO have the best draw ratio and better thermal stability than PVA fiber. Coagulation bath temperature, stretch nozzle, air pre-stretching and hot stretching for GO/PVA fibers and PVA fibers have the same effect. GO/PVA fiber that 3 times air pre-draw then hot draw at 200? has the maximum draw ratio. The maximum draw ratio, the tensile strength and modulus reached 41, 15.6 c N/dtex and 185 c N/dtex, which compared with neat PVA fiber, increased by 36.7%, 16.4% and 79.6%, respectively.