摘要
Cellular foams are widely applied as protective and energy absorption materials in both civil and military fields. A facile and simple one-step heating method to fabricate polymeric foams is measured by adopting thermally expandable microspheres(TEMs). The ideal foaming parameters for various density foams were determined. Moreover, a mechanical testing machine and split Hopkinson bar(SHPB) were utilized to explore the quasi-static and dynamic compressive properties. Results showed that the cell sizes of the as-prepared TEMs foams were in the micrometer range of 11 μm to 20 μm with a uniform cell size distribution. All the foams exhibited good compressive behavior under both quasi-static and high strain rate conditions, and were related to both foam densities and strain rates. The compressive strength of the TEMs foams at 8400s^(-1) was up to 4 times higher than that at 10^(-4)s^(-1). The effects exerted by the strain rate and sample density were evaluated by a power law equation. With increasing density, the strain rate effect was more prominent. At quasistatic strain rates below 3000s^(-1) regime, initial cell wall buckling and subsequent cellular structure flattening were the main failure mechanisms. However, in the high strain rate(HSR) regime(above 5000s^(-1)), the foams were split into pieces by the following transverse inertia force.
Cellular foams are widely applied as protective and energy absorption materials in both civil and military fields. A facile and simple one-step heating method to fabricate polymeric foams is measured by adopting thermally expandable microspheres(TEMs). The ideal foaming parameters for various density foams were determined. Moreover, a mechanical testing machine and split Hopkinson bar(SHPB) were utilized to explore the quasi-static and dynamic compressive properties. Results showed that the cell sizes of the as-prepared TEMs foams were in the micrometer range of 11 μm to 20 μm with a uniform cell size distribution. All the foams exhibited good compressive behavior under both quasi-static and high strain rate conditions, and were related to both foam densities and strain rates. The compressive strength of the TEMs foams at 8400s^(-1) was up to 4 times higher than that at 10^(-4)s^(-1). The effects exerted by the strain rate and sample density were evaluated by a power law equation. With increasing density, the strain rate effect was more prominent. At quasistatic strain rates below 3000s^(-1) regime, initial cell wall buckling and subsequent cellular structure flattening were the main failure mechanisms. However, in the high strain rate(HSR) regime(above 5000s^(-1)), the foams were split into pieces by the following transverse inertia force.
基金
financially supported by the National Natural Science Foundation of China(Nos.51572208 and 51521001)
the National Key R&D Program of China(No.2018YFB0905600)
the 111 Project(No.B13035)
the China Postdoctoral Science Foundation(No.2018M632935)
the Nature Science Foundation of Hubei Province(No.2016CFA006)
