Abstract: A single component, extremely low viscosity, pre-catalyzed high functionality diepoxide and epoxy resin system has been developed. This resin system has good thermal stability, an extended work life and is capable of being refrigerated to -18 C. and stored for extended periods of time with little or no change in physical or mechanical properties. The resin system has direct applications in a number of industries including, but not limited to, the aircraft and spacecraft industries. The resin system is a mixture of specific epoxy resins and curing agents that when combined form an extremely low viscosity resinous system that may be readily cured at a temperature as low as 52 degrees C. into novel thermoset materials prepared therefrom, which are characterized by superior strength properties and methods for preparing the same.

Abstract: A novel structural member, such as a tennis racket frame, having an unusually high strength to weight ratio is provided comprising an expanded foamed plastic core integrally bonded to a shell comprising at least one layer of resin-coated unidirectionally oriented graphite fibers, the shell completely encasing the core at any transverse cross section of the structural member, said core comprising from about 25 to about 75 volume percent of a low density cellular filler material, such as chopped cork, and from zero to about 60 weight percent of a high density weight control material, such as barium sulfate.

Abstract: A novel structural member, such as a tennis racket frame, having an unusually high strength to weight ratio is provided comprising an expanded foamed plastic core integrally bonded to a shell comprising at least one layer of resin-coated unidirectionally oriented graphite fibers, the shell completely encasing the core at any transverse cross section of the structural member, with a seamless sleeve made of a thin, flexible cellulosic film between the core and the shell.The structural member is prepared by arranging within a mold cavity an outer shell comprising at least one sheet of resin-coated unidirectionally oriented graphite fibers and a core comprising a foamable resin composition while the core is maintained within a seamless sleeve made of a thin, flexible cellulosic film, sealing the mold cavity and activating the foamable resin composition to cause expansion and generate pressure within the mold cavity and thereby provide intimate bonding of the core to the shell.

Abstract: A novel structural member, such as a tennis racket frame, having an unusually high strength to weight ratio is provided comprising an expanded foamed plastic core integrally bonded to a shell comprising at least one layer of resin-coated unidirectionally oriented graphite fibers, the shell completely encasing the core at any transverse cross section of the structural member, said core comprising from about 25 to about 75 volume percent of a low density cellular filler material, such as chopped cork, and from zero to about 60 weight percent of a high density weight control material, such as barium sulfate.

Abstract: A novel structural member, such as a tennis racket frame, having an unusually high strength to weight ratio is provided comprising an expanded foamed plastic core integrally bonded to a shell comprising at least one layer of resin-coated unidirectionally oriented graphite fibers, the shell completely encasing the core at any transverse cross section of the structural member, with a seamless sleeve made of a thin, flexible cellulosic film between the core and the shell.The structural member is prepared by arranging within a mold cavity an outer shell comprising at least one sheet of resin-coated unidirectionally oriented graphite fibers and a core comprising a foamable resin composition while the core is maintained within a seamless sleeve made of a thin, flexible cellulosic film, sealing the mold cavity and activating the foamable resin composition to cause expansion and generate pressure within the mold cavity and thereby provide intimate bonding of the core to the shell.