Density fluctuation in amorphous polymers by small angle x-ray scattering

Abstract

Density fluctuations in an infinite volume can be obtained by extrapolating the scattering intensity to the zero scattering angle, while those in a finite volume having a radius of several tens of Angstrom can be obtained from intensities at non-zero scattering angles. Small angle X-ray scattering intensities for condensed phases were approximated by I(s)=I(0)exp(As2). This s dependence of the intensity arises from the repulsive interaction between two particles. Since the density fluctuations in the above two types of volume (infinite and finite) were nearly the same in magnitude and temperature dependence for an amorphous polymer (PMMA), it was concluded that no density fluctuations due to structural inhomogeneity exist. The temperature dependence of the density fluctuations in a finite volume for PMMA and PC exhibited a second transition temperature T*below Tg, the glass transition temperature. © 1984 The Society of Polymer Science, Japan.