![]() ![]() Small and large angle light scattering measurements of the static structure factor S(q) as a function of shear rate will be used to follow flow-induced structural changes. In situ measurements of flow-induced alignment of polymers will be performed using birefringence. In addition to extensive rheological measurements of shear and normal stresses, in situ direct measurements of the degree of association will be performed as a function of shear rate using uv/vis absorption spectroscopy. The degree of the association (or lifetime of associations) will be controlled by the addition of cosolvents which serve as "poisons" for the associating groups. The degree of branching at the physical crosslinks will be controlled using metal ions with different coordination numbers. The functional groups will be placed in one of four configurations: (1) at one end of each chain or (2) at both ends of the chains or (3) halfway along the backbone of the chains or (4) at both ends and halfway along the chain length. Highly monodisperse polymers, with well defined molecular weights, will be synthesized and will be quantitatively end-capped with functional groups designed to promote associations between polymers. A coordinated, three-pronged approach is proposed which involves the synthesis of new functionalized polymers, measurements of rheological and shear- induced structural changes, and theory. Primary Place of Performance Congressional District:ĩ870128 Pine The objective of this research is to develop a fundamental understanding of shear thickening and flow-induced gelation in associating polymer solutions. ![]() Glenn Fredrickson (Co-Principal Investigator).David Pine (Principal Investigator) Timothy Deming (Co-Principal Investigator). ![]() Experimental and Theoretical Studies of Shear-Thickening in Associating Polymer Solutions NSF Org:Īndrew Lovinger (703)292-4933 DMR Division Of Materials Research MPS Direct For Mathematical & Physical ScienįY 1998 = $115,000.00 FY 1999 = $115,000.00 FY 2000 = $115,000.00 ![]()
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