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Poly(decamethylene terephthalamide) PA10T with different relative viscosities (RV) were successfully produced by the reaction of 1,10-decanediamine and terephthalic acid through molecular weight regulator benzoic acid (BA). RV was shown to be decreased linearly with increasing BA concentrations and detailed structures of PA10Ts were characterized by 13 C-NMR. Fluidity of PA10T with varying molecular weight was tested and low RV PA10Ts were used as modifiers to improve fluidity behaviors of high RV PA10Ts, meanwhile mechanical properties were maintained.

The phase behavior and phase‐separation dynamics of polystyrene/polyvinyl methyl ether (PS/PVME) blend with a critical composition of 70 vol % PVME were examined with a light scattering technique under a shear‐rate range of 0.1–40 s−1. If the shear rates were less than 8 s−1 and the starting temperatures of the measurement were 343 and 383 K, respectively, two cloud points were observed, whereas after the shear rate was higher than 8 s−1, only one cloud point existed, 20 K higher than that of the static state of the blend. Investigation of the phase‐separation dynamics at 443 K suggested that in the vorticity direction the phase‐separation behavior at the early stage and the later stage can be explained by Cahn–Hilliard linearized theory and the exponent growth law, respectively. Phase separation occurs after a shearing time, which was called a delay time τd. The delayed time τd, the apparent diffusion coefficient, and the exponent term of the blend show strong dependence on shear rates. A theoretical prediction of the phase behavior of PS/PVME under a shear flow field by introducing an elastic energy term into Flory's equation‐of‐state theory was made, and the prediction was consistent with the experimental results. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 661–669, 2003