Synthesis and Compressive Response of Microcellular Foams Fabricated from Thermally Expandable Microspheres
- 16 Downloads
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 8400 s−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 3000 s−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 5000 s−1), the foams were split into pieces by the following transverse inertia force.
KeywordsThermally expandable microspheres Compressive response Split Hopkinson bar (SHPB) Microcellular Failure mechanism
Unable to display preview. Download preview PDF.
This work was 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), and the Nature Science Foundation of Hubei Province (No. 2016CFA006).
- 1.Gibson, L. J.; Ashby, M. F. in Cellular solids: structure and properties. Cambridge university press: 1999.Google Scholar
- 2.Eaves, D. in Handbook of Polymer Foams. Natl Book Network 2004.Google Scholar
- 4.Lee, S. T.; Ramesh, N. S. Polymeric Foams: Mechanisms and Materials. IEEE Electrical Insulation Magazine 2004, 21, 56–56.Google Scholar
- 7.Zhang, R.; Zhang, L.; Zhang, J.; Luo, G.; Xiao, D.; Song, Z.; Li, M.; Xiong, Y.; Shen, Q. Compressive response of PMMA microcellular foams at low and high strain rates. J. Appl. Polym. Sci. 2018,135, 46044.Google Scholar
- 8.Sun, X.; Kharbas, H.; Peng, J.; Turng, L. S. A novel method of producing lightweight microcellular injection molded parts with improved ductility and toughness. Polymer 2015, 50, 102–110.Google Scholar
- 12.Morehouse, D. S.; Tetreault, R. J. Expansible thermoplastic polymer particles containing volatile fluid foaming agent and method of foaming the same. 1971, US Patent 3615972.Google Scholar
- 17.Andersson, H.; Ahmadian, A.; Wijngaart, W. V. D.; Nilsson, P.; Enoksson, P.; Uhlen, M.; Stemme, G. in Micromachined flow–through filter–chamber for solid phase DNA analysis. Springer: 2000, 473–476.Google Scholar
- 23.Shen, Q.; Xiong, Y. L.; Yuan, H.; Luo, G. Q.; Liang, X.; Zhang, L. M. The fabrication and characterization of polymeric microcellular foams with designed gradient density. J. Phys: Conf. Ser. 2013, 419, 012009.Google Scholar
- 28.Sharpe, W. N. in Springer handbook of experimental solid mechanics. Springer Science & Business Media: 2008.Google Scholar
- 29.Chen, W. W.; Song, B. in Split Hopkinson (Kolsky) Bar, Design Testing and Applications. Springer, New York, 2015.Google Scholar
- 32.Hay, J.; Pharr, G. ASM Handbook: Mechanical testing and evaluation. ASM Int. 2000, 8, 232.Google Scholar
- 35.Kuhn, H.; Medlin, D. ASM Handbook. Volume 8: Mechanical Testing and Evaluation. ASM Int. 2000, 9982000.Google Scholar