(205c) Bio-Based Composite Repair Resins Containing No Hazardous Air Pollutants

Unsaturated polyester-based repair resins, such as Bondo?, are widely used for automotive repair, marine repair, sporting equipment repair, and household repair of metal, composites, plastics, and wood. Commercial repair resins usually contain 10-40 wt% styrene, which is a hazardous air pollutant (HAP). The reduction of HAP usage in the Army has become a high materials need because of EPA regulations, including the Defense Land Systems for Miscellaneous Equipment (DLSME) National Emissions Standard for Hazardous Air Pollutants (NESHAP) and the Reinforced Plastic Composites NESHAP. Non-volatile fatty acid monomers can be used to replace the styrene in these repair resins. Inorganic fillers, such as talc, calcium carbonate, dolomitic limestone, sodium metaborate, glass microspheres, and milled fiberglass, were added to a vinyl ester ? fatty acid binder at various loading levels to elucidate the effects of individual fillers on the thermal, mechanical, rheological properties of the resin, as well as the effects on storage stability. Inorganic additives had little effect on the glass transition temperature of the cured resin, with the exception of sodium metaborate, which increased the temperature of the loss modulus peak by roughtly 12 ^oC at 40 wt%. The inorganic particulate fillers increased the storage modulus of the cured resin from roughly 750 MPa (zero filler) to approximately 2 GPa (40 wt% inorganic filler) at 25 ⁰C. However, hollow glass microspheres had a smaller influence on the modulus and milled fiberglass increased the modulus much more than all of the other fillers. In general, increasing the amount of inorganic particulate fillers in the resin increased the viscosity exponentially. The degree of viscosity increase and shear- and time-dependent effects were influenced by particle size, morphology, and particle-matrix interactions.