Elucidating Fundamental Polymer Structure-Property Relationships via Extensional Rheology
Extensional flow refers to a type of deformation that involves the stretching of viscoelastic media. It is the dominant type of deformation in converging and squeezing flows that occur in typical polymer processing operations such as in injection molding, extrusion, blow molding, film blowing and calendering. Uniaxial extensional flow measurement is particularly useful in polymer characterization because it is the 'strongest' flow field one can generate with respect to both polymer chain stretch and molecular alignment. Consequently, uniaxial extensional flow characterization is very sensitive to the molecular structure/architecture of the polymeric system being tested.
Although such experiments were difficult to perform in the past, due to recent advancements in the field of experimental extensional flow rheology, extensional flow characterizations can now be easily performed in the laboratory utilizing commercially available fixtures hosted on torsional rotational rheometers. In addition to elucidating macrostructural features such as molecular weight, molecular weight distribution, and polymer long-chain branching, when coupled with in-situ supplemental experimental techniques such as flow birefringence and light, x-ray or neutron beam scattering, extensional rheology can be used to gain valuable fundamental insight into flow induced crystallization of polymers during extension flows as well as localized flow phenomena at large and high rates of deformaion - issues that are pivotal in understanding, modeling, and predicting polymer processing and polymer product behaviors. Experimental results demonstrating these various testing techniques will be presented for a number of polymeric materials.
2014-09-29, 11:00 - 12:00
Trainer: Dr. Martin Sentmanat
Dr. Sentmanat received his B.S. (1990) in Mechanical Engineering from Texas A&M University in College Station, TX, and then headed north to Montreal, Canada where he received his M.Eng. (1992) and Ph.D. (1995) in Chemical Engineering from McGill University under the supervision of Prof. John M. Dealy. Dr. Sentmanat began working as a Senior Research Physicist at The Goodyear Tire & Rubber Company at Corporate Research in Akron, OH back in 1995, and after authoring more than two dozen worldwide patents left Goodyear at the end of 2003 to found Xpansion Instruments, exclusive manufacturer of his invention, the SER Universal Testing Platform, which has served to redefine the paradigm in experimental extensional rheology and miniature-scale materials testing. Based now in the Austin, TX area, Dr. Sentmanat also serves as the President of Polymer Consulting Group, a firm that has catered to the polymer, biomedical, oil & gas, and scientific legal communities since 2003.
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Tel.: +1 - 804 - 550 - 1051
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