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The viscoelastic properties of polyisobutylene filled with sodium carboxymethylcellulose were studied. Using shear viscosity data, the relaxation time, λ, defined as the ratio η/ G of the initial viscous and elastic constants was evaluated. The flow activation energy, melt flow index and superposition shift factor were also determined and master curves were generated. A relatively small effect of filler concentration on viscosity was observed, whereas its effect on λ and the initial first normal-stress coefficient, ψ, was found to be significant. [ABSTRACT FROM AUTHOR]

Isothermal phase dissolution of regularly phase-separated structures at deep quench depths below the lower critical solution temperature was studied by light scattering technique for the blend of poly(styrene-co-acrylonitrile) and poly(methylmethacrylate). The phase dissolution studied in this work was that in the diffusion-controlled regime. During the process of phase dissolution the light scattering intensity decays exponentially with time at a rate depending on an effective diffusion coefficient for the center-of-mass motion of the chain molecules in the melt. The diffusion coefficient and the associated activation energy were estimated to be in the order of 10 cm/s and 50 kJ/mol, respectively. [ABSTRACT FROM AUTHOR]