Design of polymer composites with improved adhesion and wear properties

In this study, three projects were pursued to develop novel polymer composites with improved adhesive and wear properties.;The first project addressed the moisture resistance issue that is endemic to silane coupling agents. Silanes have been used as the coupling agent (CA) for glass fiber reinforced epoxy matrices for over half a century. The problem associated with silanes that remains unresolved is that with moisture present, the bonding between the silanes and the glass fiber surfaces can be reversed causing the tensile strength of the matrix to drop. Aromatic Thermosetting Polyesters (ATSP) that were developed in the Economy group have the potential to react with both the glass fiber surface and the epoxy matrix, and hence were proposed as a CA to replace silanes. Single Fiber Fragmentation Tests (SFFT) after environmental treatment showed that matrices using ATSP as the CA had a twofold improvement in the moisture resistance comparing to the ones using silanes. This demonstrates that a new CA with better performance has been found.;The second project involves developing a PTFE based composite that has low wear, low friction and ease of fabrication. For years, people have sacrificed the low friction of pure PTFE by blending it with other materials to improve wear. This approach is complicated because of the difficulty of fabricating blends of PTFE with small amounts of graphite, PEEK or polyimide. In this work, fully cured ATSP powder, which displays similar processing conditions to PTFE, was blended with PTFE to form composites over the entire composition range of ATSP/PTFE. The composites fabricated in this fashion require pressures and temperatures lower than the ones for pure PTFE and have shown comparable friction and lower wear compared to commercial PTFE composites.;In the third project, an 1-methyl-2-pyrrolidinone (NMP) solution of ATSP oligomer was cast on a metal surface. Tribological tests showed that when ZonylRTM was present as a third body during sliding, the ATSP system had low friction and much lower wear compared to a commercial PTFE based coating. TOF-SIMS analysis showed that ZonylRTM particles had migrated down into the coating at least 1.5 microm deep when the wear track was only 0.2 microm deep, which means that a ATSP and Zonyl RTM composite had formed due to pressure and sliding. It is believe that ATSP with ZonylRTM coating system has very promising prospects for use as a soft protective coating for tribological applications.