9310762 Graessley It is proposed to develop a broad base of fundamental information on the melt state thermodynamics of polyolefin blends. This will be accomplished by a combination of techniques -- small-angle neutron scattering to evaluate thermodynamic interactions in the single phase region, laser light scattering to confirm the location of phase boundaries, and equation-of-state measurements to assist interpretation and generalization of the results. The previous studies with model polyolefins, synthesized by saturating the double bonds on nearly monodisperse polydienes, will be extended. Structurally uniform polyolefins with well-defined molecular weight distributions, made by metallocene (single site) catalysts, will now be included. Aside from supplying thermodynamic information for an extremely important class of polymeric materials, the proposed work will provide tests of current theories of thermodynamics for polymeric mixtures where the local interactions are simple, at least in principle, and the local structures are well defined. The result will be useful in guiding the development of new blends based on polyolefins as well as the mixing of structures in plastics recycling. ***
