Tuning the properties of segmented polyurea by regulating soft‐segment length

Abstract

ABSTRACTPolyurea is being widely advocated as a “retrofit” coating on structures, which mandate protection against blast. The physical properties of polyurea can be tuned by judicious choice of reactants, and the processing methodology employed for its preparation. The purpose of this study is to establish the dependence of material properties on the soft segment length in polyurea. Polyurea formulations were prepared by reaction of commercially available isocyanate prepolymer with poly(propylene oxide) based amines of varying molecular weights (230–2000 g/mol). The effect of increasing the soft segment length on the mechanical properties of polyurea under both quasi‐static as well as dynamic conditions was determined. Ductility was found to increase proportionally with increasing soft segment length, with a concomitant decrease in the tensile strength. All the compositions exhibited sub‐ambient glass transition temperature, which was found to reduce with increasing soft‐segment length. Time–temperature superposition principle was used to arrive at master curves for all compositions. The frequency essential to initiate the process of dynamic “rubber to glass” transition was found to be directly proportional to the soft segment length. All the formulations were found to be capable of exhibiting an elastomeric response even under high frequencies typical of blast loadings. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46284.