The role of iodine treatment in enhancing the optical and structural properties of stretched nylon 6 fibres

Abstract

Stretched nylon 6 fibres are treated with iodine at 50 °C at different time intervals. The effects of the treatment on the optical and structural parameters are investigated. Using the double-beam Pluta polarizing interference microscope, the interference patterns are recorded for the investigated samples and used for calculating the refractive indices, birefringence and other optical properties. The refractive indices and the birefringence values are directly proportional to the time of iodine evaporation. The iodine treatment increases the isotropic refractive index, mean polarizability per unit volume, surface reflectivity and orientation function, while decreasing the orientation angle (θ). The angle (θm) between the chain axis and the dipole moment seems to be constant. The investigated parameters show remarkable variation for the uniaxially drawn fibres to draw ratios (3 and 3.5). Moreover, the iodinated undrawn and drawn samples reveal an increase in the magnitude of the investigated parameters compared with those only annealed at the same conditions of temperature and time. The obtained results indicate that the iodine treatment modifies the nylon 6 fibre structure and consequently the optical properties, which may be useful for different industrial purposes.