Low Thermal Conductivity Fiber for Solid Rocket Nozzle Insulation (MSC P4221)

There is a critical need for replacement of viscose processed rayon-based carbon fibers for use in Solid Rocket Motor (SRM) nozzle designs. Rayon based fibers have unique thermal-structural properties which makes them an excellent ablative material in nozzle liners; but, due to undesirable processing conditions, there is no longer a domestic commercial supplier of these fibers. This proposal presents an opportunity to develop a PAN-based fiber that has been specifically processed (doped, spun, stabilized, and carbonized) to achieve the required ablative properties need for SRM nozzles. The approach will offer drop-in processing with existing acrylic precursor and conversion for minimal retrofitting of current fiber production. The carbon fiber will possess three key characteristics (1) low thermal conductivity for insulation, (2) crenulated fiber shapes for interlaminar strength, and (3) sustainability by using PAN based precursor. To accelerate the transition of this technology, the program will utilize a 100 foot pilot spin line, housed at the University of Kentucky Center for Applied Energy Research, for producing of meaningful research quantities of precursor tow (up to 1 lb/working day) and generating near full-scale fiber spinning procedures at commercial fiber plants.