Experimental Characterization and Material-Model Development for Microphase-Segregated Polyurea: An Overview

Abstract

Numerous experimental investigations reported in the open literature over the past decade have clearly demonstrated that the use of polyurea external coatings and/or inner layers can substantially enhance both the blast resistance (the ability to withstand shock loading) and the ballistic performance (the ability to defeat various high-velocity projectiles such as bullets, fragments, shrapnel, etc. without penetration, excessive deflection or spalling) of buildings, vehicles, combat-helmets, etc. It is also well established that the observed high-performance of polyurea is closely related to its highly complex submicron scale phasesegregated microstructure and the associated microscale phenomena and processes (e.g., viscous energy dissipation at the internal phase boundaries). As higher and higher demands are placed on blast/ballistic survivability of the foregoing structures, a need for the use of the appropriate transient nonlinear dynamics computational analyses and the corresponding design-optimization methods has become ever apparent. A critical aspect of the tools used in these analyses and methods is the availability of an appropriate physically based, high-fidelity material model for polyurea. There are presently several public domain and highly diverse material models for polyurea. In the present work, an attempt is made to critically assess these models as well as the experimental methods and results used in the process of their formulation. Since these models are developed for use in the high-rate loading regime, they are employed in the present work, to generate the appropriate shock-Hugoniot relations. These relations are subsequently compared with their experimental counterparts in order to assess the fidelity of these models.

Computational investigation of shock‐mitigation efficacy of polyurea when used in a combat helmet

“…To obtain these relations, a separate set of finite element analyses was carried out in which a single-material parallelepiped shaped slug (subjected to zero lateral-strain boundary conditions) impacts (at a zero obliquity angle) a rigid wall. More details regarding this type of finite element analyses can be found in our recent work (Grujicic et al, 2010b). Slug-rigid wall collision results in:…”

New polyurea MWCNTs nanocomposite films with enhanced mechanical properties

“…Polyurea has been reported as a good candidate for impulsive loading applications since it has been demonstrated that it is intrinsically reinforced by its morphology, consisting of a continuous rubbery soft matrix containing well dispersed nanoscaled hard domains . Recent studies proved that a polyurea coated steel plate could suffer lower deformations than an uncoated one when subjected to impulsive loading .…”

Electrochemical fluorescence switching properties of conjugated polymers composed of triphenylamine, fluorene, and cyclic urea moieties

“…The ability of these conjugated polymers to amplify their sensitivity on fluorescence responses is attributed to the efficient electronic delocalization and rapid transport of excitons along the π‐ conjugated backbone. Much research has been done on polyureas due to their outstanding thermal and mechanical properties 3–9. However, to our knowledge, fabrication of solid‐state electrofluorescent devices (EFD) using PU based materials has not been examined and reported.…”