Interferometric study of creep deformation and some structural properties of polypropylene fiber at three different temperatures



Influence of temperature on creep deformation for polypropylene PP fiber under a constant load was studied interferometrically. The automated multiple-beam Fizeau system in transmission was equipped with a mechanical creep device attached to a wedge interferometer. This system was used to determine the optical properties (n, n, and Δn) of PP fiber during the creep process at constant loading with varying temperature. The creep compliance was drawn as a function of both time and temperature. An empirical formula was suggested to describe the creep compliance curves for PP fibers and the constants of this formula were determined. Two Kelvin elements combined in series were used to provide an accurate fit to the experimental compliance curves. The stress–strain curve via creep was studied to determine some mechanical parameter of PP fibers, Young's modulus E, yield stress σy, and yield strain εy. The optical orientation function f(θ), the dielectric constant d, the dielectric susceptibility χ, the surface reflectivity equation image, and the average work per chain W′ were also calculated. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008