High-Performance POSS-Modified Polymeric Composites

NASA's Jet Propulsion Laboratory, Pasadena, California

Thursday, February 01 2001

Mass densities will be decreased, while strength, use-temperature range, and radiation resistance will be increased.

Epoxies and/or cyanate esters that incorporate polyhedral oligomeric silsesquioxane (POSS) compounds are undergoing development at Air Force Research Laboratory (AFRL). These formulations are expected to be useful as high-performance matrix resins for advanced, lightweight fiber/matrix composite materials for diverse applications that could include spacecraft structures, automotive structures, prosthetics, sporting goods, and general consumer goods. In comparison with the corresponding unmodified matrix resins and composite materials made with those resins, the POSS-modified resins and composite materials are expected to exhibit lower mass densities, greater stiffness, and capabilities to withstand higher temperatures and higher levels of ionizing radiation.

Preliminary experiments have confirmed expectations that in comparison with unmodified resins, POSS-modified epoxy resins exhibit enhanced properties — especially lower mass density and widened use-temperature ranges. Both analyses and favorable initial results suggest that POSS-modified matrix resins are both chemically compatible with, and capable of wetting, binding fibers to desirably high degrees.

Specific quantitative goals in the development of POSS-modified polymeric composites, relative to unmodified ones, include the following:

• Parameters that represent such matrix-dominated mechanical properties as compression strength, durability under heat/load cycling, and resistance to impact and damage, will be increased by 10 to 50 percent.
• Mass densities will be reduced by at least 15 percent.
• Use-temperature ranges will be extended by >80 °C.
• Resistance to atomic oxygen and to ultraviolet and charged-particle radiation will be increased by 100 percent.
• Flammability will be decreased and other physical properties will be enhanced.
• (This concept has not been reduced to practice.)

This work was done by Witold Sokolowski and Tim O'Donnell of Caltech, Joseph Lichtenhan of Hybrid Plastics Co., and Shawn Phillips of AFRL Edwards for NASA's Jet Propulsion Laboratory. For further information, access the Technical Support Package (TSP) free on-line at www.nasatech.com/tsp under the Materials category.

NPO-20734