Homopolymerization And Copolymerization Of Styrene Under Strong Magnetic Field

With the rapid development of modern society,the revolution of new materials has become an important force to promote the advancement of science and technology.The introduction of a magnetic field during the polymerization of organic matter can improve the properties of the material,magnetic processing technology is gradually becoming a new process for the preparation of new functional materials and has received great attention,but the simple low-strength magnetic field has a limited influence on the progress and results of the polymerization.In this paper,the free radical bulk homopolymerization and copolymerization of styrene under strong magnetic field conditions are studied,which will lay a theoretical foundation for the application of magnetic field effect in polymer synthesis.In order to ensure the simplicity and purity of the reaction system,the free radical bulk homopolymerization of styrene was first carried out under magnetic and non-magnetic fields.The results show that the application of 7 T(Tesla)strong magnetic field can shorten the induction period and increase the efficiency,the reaction rate and conversion rate of styrene homopolymerization increased compared with 0 T,and the conversion rate changed from 42.4% of 0 T to 51.3% of 7 T,However,the strong magnetic field of 7 T is not enough to affect the crystallinity of the PS(polystyrene)condensed state;In addition,the polystyrene prepared under a strong magnetic field of 7 T has a larger molecular weight,a narrower molecular weight distribution and better thermal stability than the PS prepared under a 0 T magnetic field,and its glass transition temperature increases with the strength of the magnetic field,it gradually decreased from 111.4 °C of 0 T to 64.0 °C of 7 T.At present,there are very few studies on the copolymerization reaction of magnetic field.Therefore,the free radical bulk copolymerization of styrene and acrylonitrile under different magnetic field strengths and different ratios is studied.Through research,it is found that with the increase of magnetic field strength,the induction period of styrene and acrylonitrile copolymerization under different ratios will gradually shorten and the efficiency will increase gradually,as a result,the copolymerization reaction rate and the yield of SAN(styrene and acrylonitrile copolymer)are gradually increased;Furthermore,the molecular weight of SAN synthesized under different ratios increases with the increase of magnetic field strength,but the molecular weight distribution is narrower and narrower,and the thermal stability of SAN synthesized under different ratios is more and more excellent;Moreover,with the increase of magnetic field,the percentage of St(styrene)component in SAN synthesized under different ratios will gradually increase,while the glass transition temperature of SAN will gradually decrease;In addition,the application of a strong magnetic field increases the reactivity ratio of St,while the reactivity ratio of AN(acrylonitrile)decreases,and the constant ratio point also changed,from F1=f1=0.52 of 0 T to F1=f1=0.56 at 5 T,and F1=f1=0.59 at 8 T,while The strong magnetic field of 8 T is not enough to affect the crystallinity of the condensed state of SAN,all of these results can be explained by the free radical pairing mechanism.