STTR Phase II: Nanofiber Fabrication via Melt Coextrusion for Fuel Filter Membranes

The broader impact/commercial potential of this Small Business Technology Transfer Phase II project is to demonstrate a low cost, environmentally friendly co-extrusion fabrication method for producing high surface area micro- and nanofiber based nonwoven fuel filter sheets. The micro-/nanofiber nonwoven structures are fabricated from two different hydrophilic and hydrophobic polymers in a melt co-extrusion and subsequent exfoliation processing step. The resulting porous filtration media sheets have been shown to possess superior strength, tailorable pore sizes, and fuel filtration efficiency on par with currently utilized commercial fuel filter products. These accomplishments signify a path forward to a highly scalable manufacturing process for producing low cost thermoplastic filter products in addressing the increasingly stringent EPA regulation of ppm level water contaminant. The reduced manufacturing process complexity in melt co-extrusion is estimated to provide up to 60% reduced production costs when scaled to commercial production quantities. Additionally, a significant environmental impact will be realized through adoption of this novel production technology over competitive processes owing to its ?greener? solvent-free manufacturing aspects that eliminates the annual need for millions of gallons of organic solvents and supporting reclamation equipment currently utilized by the filtration industry in creating elctrospun and wet-laid composite nonwoven filtration media. The objectives of this Phase II research project are to fabricate nano/micro scale nonwoven fibrous filter mats for fuel filters via a novel melt co-extrusion approach, with high fuel/water filtration efficiency and superior mechanical properties, in a commercially relevant production scale, towards addressing the stringent EPA 2010 filtration regulations and its upcoming revisions in 2015. The first generation filter prototypes fabricated in Phase I STTR program exhibited up to a ten-fold increase in surface area, up to a two-fold increase in porosity and up to a six-fold the deformation strength of the commercial filters. The coextruded microporous filter fiber size distribution was comparable to a commercial melt-blown process sample and superior to the leading wet-laid technology samples. Preliminary filtration efficiency experiments on the coextruded micro-fiber filtration media prototypes exhibited 60 to greater than 80 % separation of water from ultra-low sulfur diesel as compared to 80 % water separation using commercial filter under same testing conditions. The commercial interest for the new multilayered, coextruded filtration media processing technique is centered on identification of new filtration media film polymer materials, achieving nano-sized pore distributions for improved filtration efficiency and achieving scale-up production cost savings through the improved filter film processing technique.