Molecular- and Domain-level Microstructure-dependent Material Model for Nano-segregated Polyurea
Clemson University Clemson
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Purpose Polyurea is an elastomeric two-phase co-polymer consisting of nanometer-sized discrete hard i.e. high glass transition temperature domains distributed randomly within a soft i.e. low glass transition temperature matrix. A number of experimental investigations reported in the open literature clearly demonstrated that the use of polyurea external coatings andor internal linings can significantly increase blast survivability and ballistic penetration resistance of target structures, such as vehicles, buildings and fieldlaboratory test-plates. When designing blastballistic-threat survivable polyurea-coated structures, advanced computational methods and tools are being increasingly utilized. A critical aspect of this computational approach is the availability of physically based, high-fidelity polyurea material models. The paper aims to discuss these issues. Designmethodologyapproach In the present work, an attempt is made to develop a material model for polyurea which will include the effects of soft-matrix chain-segment molecular weight and the extent and morphology of hard-domain nano-segregation. Since these aspects of polyurea microstructure can be controlled through the selection of polyurea chemistry and synthesis conditions, and the present material model enables the prediction of polyurea blast-mitigation capacity and ballistic resistance, the model offers the potential for the material-by-design approach. Findings The model is validated by comparing its predictions with the corresponding experimental data. Originalityvalue The work clearly demonstrated that, in order to maximize shock-mitigation effects offered by polyurea, chemistry and processingsynthesis route of this material should be optimized.