ALKALI-METALLATION OF RAYON AND ANIONIC GRAFTCOPOLYMERIZATION OF THE METALLATED RAYON

Rayon filament yarn was metallated with Li, Na and K methoxide solutions in methanol, and then graftcopolymerized with acrylonitrile (AN) and other monomers such as methyl acrylate (MA) and methyl methacrylate (MMA) solutions in dimethyl sulphoxide (DMSO).The degree of Na-metallation vs. Na methoxide concentration curve had a maximum for the non-swollen rayon, while the degree of alkali-metallation of the swollen rayon was directly proportional to the alkali methoxide concentration irrespective of alkali ions (Li, Na or K) except for the region of lower methoxide concentration.The degree of metallation for the swollen rayon were in the order of Li>Na>K in the region of the higher methoxide concentration, while the order of Limethoxide concentration. It was assumed that the methoxide concentrations inside of the swollen fiber would be so much increased by the sorption of methoxides and the effect was more remarkable in the order of Limethoxide concentration. The activation energy of Na-metallation was obtained to be 2.4 Kcal/mol for the swollen rayon.The graft-on vs. AN concentration curve for the Na-metallated rayon had a maximum at AN 40-60 vol% in AN-DMSO medium. The graft-on vs. degree of metallation curves for Li, Na and K had maxima, respectively, and the graft-ons approached zero in the regions of higher degree of metallation. Therefore it could be presumed that the alkoxide groups were combined so strongly by polar bondings with each other that the rayon turned homy and inactive to the anionic polymerization at higher methoxide concentrations.The number average molecular weights (_??_) of the graft polymers were 1, 000-16, 000 and gave a maximum against the AN concentration in the AN-DMSO medium. The initiation efficiency of the combined Na, which was obtained from ratio of the calculated _??_ to the found _??_., also gave a maximum with increasing AN concentration.In the case of methyl acrylate as monomer, the graft-on vs. degree of metallation curves had maxima whose positions nearly coincided with the maxima of the AN grafting. These facts also would prove the assumption that the rayon turned horny and inactive at the higher methoxide concentrations.