Cyanate ester resin systems offer promise for many high-temperature polymer applications, but the potential for many applications is limited due to hydrolytic degradation of the cured polymer network, which can blister the resin, decrease its cross-linking density, and reduce the maximum allowable use temperature. This study examines the hydrolytic degradation of a Bisphenol E dicyanate ester (LECY) and a glass-fiber composite of LECY. Equilibrium water sorption, reaction rates, and glass transition temperature changes are monitored. Despite differences in diffusion and sorption, the glass fiber composite is shown to behave similarly to the neat polymer system in terms of degradation. Results were compared to PT-30 triphenolic cyanate ester, and LECY was determined to have lower equilibrium water sorption values, and a lower degradation rate.

: Montmorillonite-smectite clay consists of anisotropic clay platelets, generally a nanometer in thickness by hundreds of nanometers laterally, bound together by charge balancing cations. Clay dispersion in polymer hosts has been shown to impart a number of improvements including increased barrier properties, fire resistance, reduced coefficient of thermal expansion, and superior mechanical properties all in relation to the near host polymer. The dispersion of clay in a host material occurs first by intercalation, where the host medium penetrates the galleries causing an increase in inter-plate distance, followed by exfoliation, where the clay platelets migrate away from each other disrupting long range order. A high degree of exfoliation can be difficult to achieve in many polymer hosts due to the polarity of the clay platelet and the inorganic nature of naturally occurring cations such as sodium. Dispersion may be facilitated by imparting organic character to the clay through a cation exchange with an organic ammonium salt, and also by introducing polar nature to the intended polymer host. Recently, it has been shown that clay with certain organic cations exhibits spontaneous room temperature and temperature-initiated exfoliation in hydroxyl- and carboxyl-terminated liquid polybutadiene rubbers (CTPB and HTPB, respectively) in the absence of shear. These observations represent a simple process to achieve sought after barrier properties in polymer materials in a relatively simple and reproducible manner. This work represents a more comprehensive examination of the attempted dispersion of a number of different grades of clay in HTPB using polarized optical microscopy and rheology as investigative techniques.

Fluorinated Polyhedral Oligomeric. Silsesquioxanes are hydrophobic nanoparticles. One compound, FD8T8, is ultrahydrophobic, possessing a water contact angle of 154 degrees. This is believed to be the most hydrophobic and lowest surface tension crystalline substance known. Analysis of the x-ray crystal structure indicates a large number of Si center dot center dot center dot F contacts may lead to ultrahydrophobicity. Hydrophobicity of poly(chlorotrifluoroethylene) nanocomposites also increases with the incorporation of FluoroPOSS and will be discussed.

: The introduction of inorganic nanomaterials as additives into polymer systems has resulted in polymer nanostructured materials exhibiting multifunctional, high performance polymer characteristics beyond what traditional polymer composites possess. Selective thermoplastic elastomers have been used with montmorillonite organoclays, POSS(registered), carbon nanofibers to develop a flame resistant material. Thermal and flammability properties of these polymer nanocomposites will be presented.

One of the greatest barriers in transitioning new or altered polymers to commercial application is the cost of new equipment for processing or the cost of developing parameters for the new material. One solution is developing "drop-in" modifiers that alter the properties of presently used materials without altering the processing parameters or requiring exotic equipment. Over the last decade the Air Force Research Laboratory has studied how the Polyhedral Oligomeric Silsesquioxanes (POSS) can be incorporated as blendables in industrial polymers like polypropylene to improve properties without sacrificing the ease of processing. This talk will detail the processing method (drying, blending, extruding and molding) of Octamethyl POSS/polypropylene nanocomposites. The degree of compatibility was established with visual methods.