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Issue 38, 2018
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Multi-scale progressive failure mechanism and mechanical properties of nanofibrous polyurea aerogels

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Abstract

The nonlinear mechanical properties, deformation and failure mechanisms of polyurea aerogels (PUAs) were investigated using a multi-scale approach that combines nanoindentation, analytical and computational modeling. The atomistic structure of primary particles of PUAs and their mechanical interactions were investigated with molecular dynamics simulations. From nanoindentation we identified four deformation and failure modes: free ligament buckling, cell ligament bending, stable cell collapsing, and ligament crush induced strain hardening. The corresponding structural evolution during indentation and strain hardening were analyzed and modeled. The material scaling properties were found to be dependent on both the relative density and the secondary particle size of PUAs. Using a porosity-dependent material constitutive model, a linear relationship was found between the strain hardening index and secondary particle size instead the conventional power-law relationship. Finally, the structural efficiency of PUAs with respect to the capability for energy absorption is evaluated as a function of structural parameters and base polymeric material properties.

Graphical abstract: Multi-scale progressive failure mechanism and mechanical properties of nanofibrous polyurea aerogels

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Publication details

The article was received on 30 Jul 2018, accepted on 26 Aug 2018 and first published on 27 Aug 2018


Article type: Paper
DOI: 10.1039/C8SM01546E
Citation: Soft Matter, 2018,14, 7801-7808
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    Multi-scale progressive failure mechanism and mechanical properties of nanofibrous polyurea aerogels

    C. Wu, T. Taghvaee, C. Wei, A. Ghasemi, G. Chen, N. Leventis and W. Gao, Soft Matter, 2018, 14, 7801
    DOI: 10.1039/C8SM01546E

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