Kalman Migler

National Institute of Standards and Technology

Physicist

Fellow, Elected 2018

Kalman Migler repeatedly answered challenging outstanding questions of polymer rheology, with insightful optical and mechanical experiments. He’s had a knack of choosing the right methods. To begin, Kalman used fluorescent evanescent velocimetry to measure the polymer velocity adjacent to a solid substrate and thus made the first direct evidence of polymer slippage. This work prompted deGennes and Brochard to develop their model of polymer slippage and was followed by numerous slippage observations in many polymeric systems.

In a similar topic with a different conclusion, he settled the debate over the origin of sharkskin, which is an instability encountered during polymer extrusion from an orifice. He did so by optically measuring the polymer melt flow field in the immediate vicinity of the exit, where he found compelling evidence not of slippage but that the sharkskin is caused by extensional fields exceeding critical values.

He later combined these two techniques of velocimetry and evanescent-waves in yet another way to determine the mechanism by which fluoropolymers eliminate sharkskin in polyolefins. It was long known that addition of fluoropolymers in trace amounts to certain polyolefins can eliminate sharkskin, yet there had been no direct observations of how this occurs and only speculations as to why. Cleverly using a variant of the evanescent technique, he developed a sensitive measure of the surface concentration of the fluoropolymer and made the first measurement of polymer/polymer slippage. These concepts were the basis for a new polymer processing additive by Dow DuPont Elastomers.

Kalman developed a few rheometers, most notably for small sample volume. Most recently, he combined Raman spectroscopy and rheology to measure polymer conformation and crystallization under flow, and a new commercial instrument was produced. Data from this rheometer definitively tests models that relate crystallinity and viscoelasticity. This rheo-Raman approach is likely to shed new light to understand how flow greatly enhances polymer nucleation and crystallization rates.

Kalman has thus made profound impact, developing and using innovative methods, at multiple times answering polymer rheology’s confounding questions.