Abstract
Mobilities of liquid poly(vinyl acetate) as expressed by the Vogel equation, − Inμ = B T − T 0 ), are extrapolated to negative pressure using previously determined pressure coefficients. The extrapolations are extended to P∗ = −b ( Tait) where the liquid volume becomes ‘infinite’ and the polymer chains are in the hypothetical ‘isolated’ state. By an analysis of the rotational kinetics and relationships developed previously, this procedure leads to U∗ and V∗ for the ‘isolated’ chain, where U∗ is the energy difference between the rotational states and V∗ is an energy barrier between these states. It is found that the greatest increase occurs between U∗ for the ‘isolated’ chain and U for the liquid at atmospheric pressure, with relatively little further increase up to 2000 bars. The energy barrier V, on the other hand, increases more uniformly over the entire pressure range from P∗ to 2000 bars. On the basis of the analyses of the rotational energetics and kinetics, an approach to a unified molecular interpretation of shear-induced lowering of viscosity (non-Newtonian viscosity) and shear-induced crystallization in certain flowing polymer liquids is suggested.
Published Version
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