The reduction of orientation in fibers spun from two‐phase polymer blends via the introduction of shear into elongational flow by the presence of a second phase

Abstract

AbstractA model is proposed for the reduction of orientation in spun fibers of two‐phase polymer blends. This is based on the introduction of shear into an elongational flow by the presence of a second phase. The requirement is that the dispersed phase should not deform to the same extent as the continuous phase so that the flow field in the region of each particle is perturbed. Around an isolated droplet of minor component, the shear rate in the continuous phase goes through a maximum when the extension rate in the droplet is around half that macroscopically imposed. The dependence of orientation reduction on concentration of dispersed phase is fitted well by assuming that the flow field around a particle is disturbed over a distance two to three times the particle diameter. In this case the maximum average shear rate around the particle is of the same order of magnitude as the elongation rate. The model proposed is consistent with all the observed features of orientation reduction during spinning of two‐phase blends.