Synthesis and characterization of polyisobutylene propellant binders

Substantial gains in rocket motor cost-effectiveness or performance can be achieved through improved propellant aging characteristics or better and more reproducible mechanical properties. The approach to achieving these goals is the development of a new binder based on ideal networks formed from polyisobutylene (PIB) prepolymers. PIB has a greater resistance to oxidation than polybutadiene which is used in many current composite systems.The ideal networks are generated through the use of PIB prepolymers with controlled molecular weight distributions and well defined functionality. PIB prepolymers evaluated in this study were synthesized by Dr. J. P. Kennedy at the University of Akron using the inifer process which allows close control of molecular weight distribution, functionality and types of end group. Hydroxy-terminated PIB's with molecular weights that varied from 1500 to 6000 and functionalities of 2 or 3 were synthesized. After a thorough characterization, gumstocks were prepared with isocyanate curatives of controlled functionality. The effects of M_c and plasticizer content on mechanical properties were determined in addition to the aging characteristics of the systems. Accelerated aging studies of the gumstocks were conducted.This work was performed under Contract No. F04611-82-C-0066, AFRPL/MKPA Edwards AFB, CA, Project Manager -Lt. Joseph W Lewis