Structural development of dynamically asymmetric polymer blends under uniaxial stretching

Abstract

The time-resolved small-angle X-ray scattering technique was used to investigate the structural change during uniaxial stretching of dynamically asymmetric polymer blends irradiated by an electron beam. The concentration fluctuations were enhanced by stretching and became large in particular along the direction of deformation. In the early stages of the stretch-induced enhancement of concentration fluctuations, the growth rate of their q-Fourier mode was found to have a maximum at a certain value of q [= (4π/λ)sin(θ/2), where θ and λ are the scattering angle and the wavelength of the X-rays, respectively]. A dominant mode in the enhancement of concentration fluctuations exists in the initial stage, like the early stage of spinodal decomposition for fluid mixtures. The viscoelastic effects of the growth rate were taken into consideration, so that for blends irradiated by an electron beam, elastic effects are found to significantly suppress the growth rate of concentration fluctuations at small wavenumbers.