Hard-magnetic Soft-materials and UV Degradation in Polymers

This talk discusses recent and ongoing research on behavior of soft materials, specifically updates to the theory of hard-magnetic soft-materials and UV degradable glassy polymers.

The first part of the talk is spent on sharing some updates on the theory of hard-magnetic soft-materials. These materials exploit magnetically-hard particles with high coercivity incorporated in mechanically soft materials to form a composite, which allows for shape-programmability and rapid remote actuation. Only about half a decade ago, this class of material was previously unknown, and after its introduction a tremendous amount of work has already been done expanding our knowledge and application range for this class of materials. The original model, while able to reproduce many experimental results, has been shown to be flawed, and a single major update can help with more realistic predictive capabilities.

The second part, taking more time, is devoted to more recent work to characterize and model the effect of stress on photo-degradation, and thus on the mechanical performance of cellulose acetate. Degradable polymers have emerged in everyday applications ranging from mundane eating utensils to high-tech medical devices. Many of these polymers exhibit photo-degradation, which is the result of bond cleavage in the polymer backbone due to chemical reactions, where the rate of reaction can be influenced by several factors. One can find in the current literature preliminary findings on how degradation under stress-free conditions can affect the mechanical performance. However there is a gap in the literature, we are still lacking experimental data and an appropriate continuum level constitutive framework, which we are making headway into and overview our recent progress.

Shawn Chester is currently an Associate Professor in Mechanical Engineering and the inaugural Associate Vice Provost for Research at the New Jersey Institute of Technology. Shawn was previously a postdoctoral researcher at Lawrence Livermore National Laboratory. Prior to that he obtained his PhD in solid mechanics from the Mechanical Engineering at MIT, and obtained both his BS and MS in Mechanical Engineering from NJIT.

Shawn's research focus in the past few years has been the development of experimentally validated continuum level constitutive theories for large-deformation multiphysics behavior of polymeric materials and the associated numerical implementation. His work spans most aspects of mechanics; experimental characterization, theoretical modeling, numerical implementation, and experimental validation. Shawn is the recipient of several honors and awards, including the ASME/AMD Thomas J.R. Hughes Young Investigator Award, the ASME/AMD Haythronthwaite Research Initiation Award, the Newark College of Engineering Rising Star Research Award, an NSF CAREER award, and the New Jersey Institute of Technology Excellence in Research Award.