*** 9661214 Shalaby This Phase I Small Business Innovation Research project will use a novel process for the surface-modification of organic polymers to chemically activate ultrahigh molecular weight, high tenacity, polyethylene fibers and determine their effectiveness in reinforcing organic polymeric matrices and Portland cement. Phase I entails the surface activation of the fibers to provide physicochemical compatibility with typical epoxy and acrylic resin matrices characterized and then evaluated for basic and application-relevant properties and compared with non-reinforced controls as well as controls based on untreated fibers. Results of Phase I study will be used to identify the most promising type (or types) of composites for further development and optimization in Phase II. Successful development of the proposed composites is expected to provide novel high-performance, cost-effective materials. These materials have a broad range of applications including those associated with structural epoxy composites (used in aircraft, automotive and sports equipment), high toughness dental and orthopedic acrylic composites (for prostheses), and impact-resistant cement composites (for construction of panels, rehabilitation of deteriorating bridges, and installation or repair of pavement).