The compressive behavior of isocyanate-crosslinked silica aerogel at high strain rates

摘要: Aerogels are low-density, highly nano-porous materials. Their engineering applications limited due to their brittleness and hydrophilicity. Recently, a strong lightweight crosslinked silica aerogel has been developed by encapsulating the skeletal framework of amine-modified aerogels with polyureas derived isocyanate. The mesoporous structure underlying is preserved through conformal polymer coating, thermal conductivity remains low. Characterization conducted on thermal, physical properties mechanical under quasi-static loading conditions. In this paper, we present results dynamic compressive behavior (CSA) using split Hopkinson pressure bar (SHPB). A new tubing pulse shaper was employed help reach stress equilibrium constant strain rate. stress-strain relationship determined at high rates within 114–4386 s−1. effects rate, density, specimen thickness water absorption CSA were investigated series experiments. Young’s moduli (or 0.2% offset yield strengths) rate ∼350 s−1 as 10.96/2.08, 159.5/6.75, 192.2/7.68, 304.6/11.46, 407.0/20.91 640.5/30.47 MPa for densities 0.205, 0.454, 0.492, 0.551, 0.628 0.731 g cm−3, respectively. deformation failure behaviors native density (0.472 cm−3), approximately same typical sample observed speed digital camera. Digital image correlation technique used determine surface strains images acquired photography. relative uniform axial indicated that localized compaction did not occur level ∼17%, suggesting most likely mechanism be different from condition. Poisson’s ratio 0.162 in nonlinear regime rates. samples failed generally splitting, but much more ductile than aerogels.