COMPOSITE MOTOR CASE POLYMERS THAT EXPAND ON POLYMERIZATION

Abstract

Polycyclic spiroorthoester which undergo expansion on polymerization to form resins, rather than shrinkage on polymerization, are employed in fabrication of composite, filament-reinforced, interceptor motor cases. The advantages which accrue to such use of the specified resins relate to the imparting of unique characteristics to the interceptor motor case such as increased structural strength, a reduction in the number of microcracks and voids, and improved bonding between resin and reinforcement. These unique characteristics impart benefits where needed since composite motor cases are fabricated from high strength filaments or tapes such as fiberglass, graphite, poly-p-phenyleneterephthalamide (Kevlar), in a polymeric matrix, and the primary mode of failure is due either to poor adhesion between the matrix and the filament or tapes or because of the development of microcracks or voids in the matrix. The spiroorthoester, 1,4,6-trioxaspiro [4.4]nonane, is an example of a resin modifier which converts the basic resin composition into an expandable resin. The basic resin composition is comprised of basically a three component system for use in fabrication of a graphite-composite motor case. One component EA-953A is a mixture of Bisphenol A-epichlorohydrin and epoxidized dimer of oleic acid, the second component is RD-2 which is butanediol diglycidyl ether, and the third component is TONOX 60/40 which is a mixture of 65% diaminodiphenylmethane, 10% triamines, and 25% polyamines. These components are employed in a ratio of about 100, 25, and 20 parts by weight in the HBRF-215 formulation. The spiroorthester is substituted for a portion of the second component in an amount from about 2 to about parts by weight.

Source: Google Patents

35 USC §181 Secrecy Order

Inventor

• 1DAVID C. SAYLES

Sensitive facility: Huntsville AL (NASA/Army)