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An experimentally disigned melt rheological characterization of starblock polymersScott, James Marvin January 1986 (has links)
The melt rheological behavior of structurally defined starblock polymers was investigated using the experimental design technique of response surface methodology. A rotatable central composite design (ccd) was employed with linear 2⁵ factorial structure and with axial points to fit the pure quadratic terms. Regression analysis of rheological data from styrene-isoprene and t-butyl styrene-isoprene starblock polymers was used to generate four models whose terms have a p-value ≤ 0.1. The fitted models of viscosity and elasticity were a function of temperature, weight percent uncombined diblock, frequency, casting solvent, and annealing time.
Changes in melt behavior were hypothesized to be dependent on mechanisms related to phase separation and/or architecture. The modeled behavior verified the proposed mechanisms enabling a generalization of the results to the melt behavior of block polymer systems. The guidelines for the applicability of the well known Cox-Mertz relation and WLF superposition technique, as well as the transition to the Forced High Elasticity State, are discussed in terms of melt connectivity and elasticity. / M.S.
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