Order-disorder transition in polymer-diluent systems: elastic constants

Abstract

A new theoretical model is presented to describe the effect of diluent on the elastic constants of polymer-diluent mixtures. Our theory shows the limitation of the traditional composite theories, which are based on the micromechanics and/or strain energy calculations, and points out the important role of molecular parameters. The present result is expressed in terms of both molecular and bulk elastic properties of the two components. As the diluent concentration increases, the elastic modulus decreases very slowly until a critical concentration 9, is reached. Beyond 9,, the modulus decreases rapidly. This order-disorder transition is related to the crossover between the energy and entropy contributions of the system at the molecular level. The prediction of the theory is in good agreement with experimental data.

Nanoadhesion between Rough Surfaces

“…Figure 3 also reveals that the pertinent length scale should be in the order of micron, s ϳ 1mm, that compares well with what has been reported [5][6][7][8]. The suction-cup effect induced by air bubble trapping [6] may attribute in part to the reduction in the effective elastic constant [18] and in the roughness exponent. The profile of a bubble-trapping rough surface looks quite like that of a fractal surface with a 0.3 shown in Fig.…”