Thermal Conductivity of Solid Fuel for Aerospace
Testing Hydroxyl-Terminated Polybutadiene (HTPB)
We recently visited an aersospace research institute in the the South of Europe that was focussed on improving the thermal properties of solid fuel for more efficient and safe space travel. C-Therm's modified transient plane source sensor technology has widely been recognized as the most effective and safe means of measuring such energetic materials. The challenges with most techniques for thermal conductivity measurement is that they either put too much energy into the sample (e.g. Laser Flash Diffusivity) or they require too large a sample volume (e.g. Guarded Hot Plate, Guarded Heat Flow, and traditional Transient Plane Source techniques) to measure safely. C-Therm's MTPS sensor technology used in the TCi Thermal Conductivity Analyzer was originally specially developed for the US Navy's Indian Head Surface Warfare Division for the characterization of energetic materials. The important considerations in the design of any technique for thermal conductivity measurement of an energetic in safely measuring the material include:
- employ a low energy / short time measurement
- minimize the sample volume requirements
- minimize the drop height of placement of the sample
- minimize any potential for impact, friction or ESD (electrostatic discharge) in grounding the components properly
- minimize the opportunity for powder ingression
For more background information on testing the thermal conductivity of explosives visit here.
Typically the energetic samples we've been asked to characterize in the past have been powder, compressed powder cakes, or emulsion formats. This recent visit to the research institute introduced more solid sample formats in energetics. The sample is pictured below on the TCi sensor. It is actually very stable at room temperature conditions. As the TCi can also easily test solids it is very straightforward to test just as you would in testing a ceramic, polymer, foam or metal with the sensor technology. Sample were constructed of hydroxyl-terminated polybutadiene (HTPB) and various different loadings of nano material used to increase the thermal conductivity of the solid fuel .
TCi Sensor: Characterizing the Thermal Conductivity of HTPB Solid Fuel (+ nano material)
Sample test results on HTPB solid fuel