INTERPLAY OF ORIENTATIONAL ORDER AND VISCOELASTICITY IN SUPERCOOLED LIQUIDS NEAR THE GLASS-TRANSITION

The problem of the liquid-glass transformation continues to be a chall enging one. It has been recently tackled by several high-powered theor ies such as mode-mode coupling. By contrast, the present model employs the intuitive picture of local orientational order in supercooled liq uids and combines this with a variant of the Maxwell model of viscoela sticity. The resulting dynamic theory provides a simple scenario of ho w the viscosity of a supercooled liquid is enhanced due to its tendenc y to order orientationally. An important by-product is an expression f or the glass-transition temperature in terms of the microscopic parame ters of the theory, via which a connection with the formal, spin-glass theoretical approach can be established. The model leads to expressio ns for the dynamical modes in a supercooled liquid-quantities of direc t experimental interest.