The talk focuses on viscoelastic materials. One of the most modern theories of continuum mechanics is the multiple natural configurations theory originally developed by K R Rajagopal. It assumes that as a body is subjected to a thermodynamic process, the body's underlying natural configuration evolves in such a way that the rate of entropy production is maximized.  The theory delivers the constitutive equation for the stress tensor in terms of a tensor related to the natural configurations, tensor that is itself a solution of an evolutionary equation, so one is confronted to a system of equations. On the other hand, kinetical theories deliver constitutive equations in terms of a first statistical momentum the weight function of which is the so-called configurational probability density (CPD). This CPD is a solution of a parabolic type PDE which needs to be explicitly solved to obtain the stress tensor.  A comparison and establishing a link between the two approaches is expected to lead to simplifications in obtaining the stress tensor for polymeric liquids.