Low Thermal Conductivity Fiber for Solid Rocket Nozzle Insulation - MSC P4443

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 program 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. In order to reduce technical risk and sufficiently demonstrate performance in a representative SRM nozzle environment, larger scale production of the prototype fiber is proposed in combination with use of alternate resin systems (e.g., benzoxazine (BXA) phenolics) to develop, manufacture and test a representative ablative/insulative composite structure. Targeted benefits of the proposed technology include lower cost, improved thermal/mechanical performance, reduced weight and processing time, and sustainable domestic sourcing.