부산대학교 도서관

Polyureas, formed by the rapid reaction between isocyanatesand diamines, are attractive for various applications due to theiroutstanding mechanical properties, which can be tuned by varying componentchemistry, molecular weight, and stoichiometry. Polyureas synthesizedfrom a modified methylene diphenyl diisocyanate (Isonate 143 L) andpolytetramethylene oxide-di-p-aminobenzoate (VersalinkP1000) are widely utilized and investigated for energy absorbing applicationssuch as impact mitigation and ballistic protection. In order to developa more complete understanding of their mechanical response, we explorethe effect of uniaxial strain on the phase separated microstructureand molecular dynamics. We utilize wide- and small-angle X-ray scatteringto investigate amorphous segment and hard domain orientation, andbroadband dielectric spectroscopy for interrogation of the dynamics.Uniaxial deformation was found to significantly perturb the phase-separatedmicrostructure and chain orientation and result in a considerableslowing down and broadening of the polyurea soft phase segmental relaxation. [ABSTRACT FROM AUTHOR]