Research Summaries

Back In-situ Molecular Diagnostics for Polymer Composites

Fiscal Year 2016
Division Graduate School of Engineering & Applied Science
Department Physics
Investigator(s) Hooper, Joseph P.
Sponsor Defense Threat Reduction Agency (DoD)
Summary The primary objective of this program is to develop molecular stress and temperature diagnostics for heterogeneous polymer composites undergoing high strain-rate deformation and impact. In contrast to traditional approaches such as photoelastic coatings or large embedded sensor gauges, our focus is on integrating molecules that respond to pressure and/or temperature, are incorporated into the polymer system with no change in mechanical properties, and allow easy remote analysis via spectroscopy or optical diagnostics. Many of the events of relevance to this program (such as the onset of hot spots in an explosive following impact) occur at very high strain-rates (103-107 s-1) and microsecond timescales, and we require sensing ability that can perform in this regime. In this context, we have designed and synthesized a new class of thermochromic material that integrates well into hydroxyl-terminated polybutadiene (HTPB) – HTPB is one of the most commonly used binders in warheads and high-performance solid rocket motors – and characterized its activation kinetics under fast temperature ramp. Based on the success of these initial studies, we propose to synthesize a complementary thermochromic switch with a different spectral signature and kinetics and study their properties under high-strain rates, as well as demonstrate the compatibility of these small molecule sensors with plastic-bonded explosive warhead formulations. We anticipate that these investigations will lead to a viable route to track and measure the formation of the localized hot spots in explosive material and provide a method to validate simulations with experimental information for the first time.
Keywords Counter-WMD Explosives Safety Weapons
Publications Publications, theses (not shown) and data repositories will be added to the portal record when information is available in FAIRS and brought back to the portal
Data Publications, theses (not shown) and data repositories will be added to the portal record when information is available in FAIRS and brought back to the portal