Investigation of Thermochemical Effects on Blowoff of Reentry Vehicle Heatshield Resins.

摘要

Demonstration of a clear correlation between measureable thermodynamic properties and the impulsive momentum developed during blowoff would place predictive techniques on a more secure foundation and might make possible the formulation of resins with thermochemical properties specifically chosen for minimum blowoff damage. To find such a correlation, a set of modified phenolic resins was prepared which had similar elemental compositions and physical properties, but which differed strongly in their thermochemical parameters. Exposure of these samples on the Ion Physics Corporation Neptune B electron facility, with measurement of impulse by ballistic pendulum, yielded data which displayed a linear correlation between heats of decomposition and an additive term in the En function derived from measured impulses through simple BRAY theory. Evidence was also found for a broadening of the electron deposition profile at early times. The techniques developed are applicable to a larger set of sample materials, and particularly to resins of more practical interest. (Author-PL)