EFFECT OF A SOLVENT MIXTURE OF H_2O/DMSO ON THE ACRYLONITRILE-N-VINYL-PYRROLIDONE COPOLYMRIZATION

In order to obtain hightenacity acrylic precursor fibers, a H2O/DMSO mixture suspension technique was used in the production of highperformance acrylonitrile(AN)Nvinylpyrrolidone(NVP) copolymer. The effect of the composition of solvent mixture on the reaction kinetics of copolymerization was studied and the overall activation energy was calculated. The structures and properties of copolymer samples were characterized by GPC, elemental analysis and IR. These showed that with an increase of DMSO concentration in the solvent mixture, the copolymerization conversion drops off slowly, and the product number average molecular weight, Mn decreases. In addtition the distribution of relative molecular weights broadens and the stereospecific sequence portion of copolymer gradually reduces. The values of reactivity ratios calculated by the method of KelenTudos for AN and NVP are: rAN=0.656±0.015 and rNVP=2.11±0.18. It is also suggested that good PAN precursor fibers can also be obtained from AN/NVP copolymers obtained at a H2O/DMSO weight ratio of 80/20 and a temperature of 60?℃.