Effects of strain-rate and temperature on mechanical behavior of polyimide foam in compression

Abstract

Polymeric materials are now major materials used in various situations. However, most polymers are usually unsuitable for use in high temp. environments because of low glass transition temp. In polymers, however, polyimide is one of polymers having relatively higher glass transition temp. and high strength. This means that the mech. property of polyimide has been said not to be changed very much by temp. Therefore, polyimide foam is expected to show good mech. performance over wide temp. range. In order to increase the use of a polyimide foam in industrial applications, it is necessary to know its deformation behavior in wide range of strain rates and temp. In this study, a series of compression tests at various strain rates, from 10-3 to 103 s-1 were carried out in order to examine the effect of strain rate on the compressive properties of polyimide foam. It was found that the flow stress of polyimide foam increased dramatically at dynamic strain rates. The effect of ambient temp. on the properties of polyimide foam was also investigated at temp. from -190 °C to 270 °C. The flow stress decreased with increasing temp. in the range from room temp. to 270 °C. At -190 °C, the deformation behavior of polyimide foam changed to be brittle. [on SciFinder(R)]