For methoxymethylation of nylon-12 films unannealed and annealed at 100°C, the relation between their melting temperature and the substitution ratio of methoxymethyl residue was investigated by DSC. Melting peak temperatures in the 1st-run were a little higher than or nearly equal to that of nylon-12, independent of the substitution ratio. This result means that the methoxymethylation was not effective in suppressing the thickening of crystal or recrystallization by heating. Melting peak temperature in the 2nd-run decreased with increasing substitution ratio. The application of the modified Flory's equation (1) (a=2) to the melting peak temperatures in 2nd-run led the heat of fusion of 17.5_??_19.5 cal/g for the monoclinic (or pseudohexagonal) crystal.
Deposition of polymer latex onto nylon 6 fibers, ungrafted or grafted with acrylic and methacrylic acid, in shaking conditions was studied with regard to pH dependence of the amount of deposition of polystyrene [PS], styrene/acrylic acid copolymer [P (St/AA)] and styrene/acrylamide copolymer [P (St/AAm)] latices, all prepared without emulsifier. With decreasing pH in acidic region, the amount of deposition of each latex onto both ungrafted or grafted fibers increased remarkably, while scarce deposition was observed in alkaline region. With increasing degree of grafting, the amount of deposition of each latex decreased because of steric hindrance due to water-soluble polymer layer formed by polymer chain grafted on the fiber surface. The amount of deposition of latex at pH 4 onto the fiber decreased in the order of P (St/AAm)>PS>P (St/AA). These results suggested the existence of bridging effect between the polymer chain on P (St/AAm) latex and the fiber, and of electrostatic repulsion force between P (St/AA) latex and the fiber. The deposition was more remarkable with shaking than without, regardless of the type of latex.
For introducing high concentration of functional groups on the surface of polyester fibers, thin layer grafting of methacrylic acid (MA) was applied to polyester fiber by direct electron irradiation. Radial distribution of concentration of MA in the thin surface layer of the grafted fiber was examined by measuring the optical reflectivity of the surface dyed after concecutive alkali hydrolysis of the grafted fiber. By the alkali treatment of graft fiber it became clear that the concentration of MA was relatively low on the fiber surface, showed a maximum at the inner part within 1μm from the surface, and then decreased toward the inner regions of the fiber. From above results we expect that by shaving the surface by a proper quantity through alkali treatment and thus exposing the surface with the maximum concentration of functional group, we can give a high concentration of functional groups at the surface of polyester fibers. Actually MA graft polyester fibers showed excellent dyeability by grafting even below 1%, through alkali treatment.
Fading reaction of azo dyes in aqueos solution with sodium hypochlorite through oxidation was investigated. The use of the apparent initial reaction rate constant in the interpretation of the reaction was proposed. The addition of water soluble polymer having nitrogen atom was found to retard the fading reaction. The mechanism of the retardation was discussed.