In the present work, we characterize the rheological behavior of 10 nearly monodisperse poly(ethyl acrylate) samples, whose molar mass ranges from 1200 to 150 000 g/mol. The poly(ethyl acrylate)s were obtained by means of a controlled/living radical polymerization technique. The time-temperature superposition principle works, and the T dependence of the horizontal shift factor a(Tr)(T) is fairly well described by the Williams-Landel-Ferry law. Furthermore, the zero-shear viscosity dependence on the temperature, for all the investigated samples, has resulted to be well described by means of Vogel-Fulcher laws. The mass dependence of thermal parameters such as the Vogel temperature T-0 and the pseudo-activation energy T-b has been worked out and compared to the mass dependence of the glass transition temperature T, This leads us to propose here a coherent way to describe their behavior and estimate several microscopic parameters in terms of free volume. Moreover, the molar mass dependence of material parameters has been investigated. The zero-shear viscosity eta at different temperatures has been evaluated, and the critical mass value has been found to be M-c = 26 000 g/mol. The ratio between the critical M-c and the entanglement mass M-e has been found to be about 2.2 from the evaluation of the plateau modulus G(N)(0). A mass dependence analysis of the steady-state compliance J(e)(0) has also been carried out from which the second critical mass M-c' is inferred.
|Autori interni:||ANDREOZZI, LAURA|
|Autori:||L. ANDREOZZI; VALTER CASTELVETRO; M. FAETTI; M. GIORDANO; AND F. ZULLI|
|Titolo:||Rheological and Thermal Properties of Narrow Distribution Poly(ethyl acrylate)s|
|Anno del prodotto:||2006|
|Digital Object Identifier (DOI):||10.1021/ma052190+|
|Appare nelle tipologie:||1.1 Articolo in rivista|