Extrusion of Microcellular Foams and Foam Composites
Introduction Conventional extrusion of microcellular foams using supercritical carbon dioxide as a blowing agent needs expensive equipment or specialized modification in order to operate. High pressure and high temperature seals are required on the extruder barrel at the injection for the supercritical fluid. The mixing of the gas and polymer phases in the extruder barrel requires specialized screws. The blowing agent is injected directly into the extruder barrel while the polymer is in its molten state. The injected blowing agent is in a two-phase mixture with the polymer melt before the formation of a gas-polymer solution. For enabling uniform dissolution, mixing enhancers and complex screw designs are required in the extruder, further adding to the complexity and cost of the system. The conventional process may result in having an inconsistent concentration of gas in a given volume of the polymer melt. Also, a blowing agent metering device external to the extruder is required to monitor the amount of supercritical fluid delivered to the polymer melt. Technology description Researchers at the University of Washington have developed a melt extrusion process using solid-state nucleation phenomenon in gas saturated thermoplastic materials to create microcellular thermoplastic foams. This process uses sub-critical gases, and therefore does not need the specialized equipment required to deliver the gas at supercritical pressures. Further, since it relies on solid state-nucleation, the specially designed nozzle used in the conventional process is not needed, and the melt goes directly through the die to create the desired profile. Also, in the process of the invention, a uniform gas-polymer mixture is obtained in the solid-state hence no specialized screws are required. Business opportunity This process can be used to produce a variety of products including but not limited to energyefficient and higher impact vinyl window profiles, high-strength insulating polystyrene cores for structural insulated panels, insulating and impact resistant polyester and vinyl wall exterior siding for homes and office buildings, low-cost recycled PET decking products, and fence posts. Most solid plastic products that are produced in extrusion could be potentially replaced by microcellular extruded plastics. Thus, the potential scope of applications is very large. Intellectual property position This technology is available for licensing. U.S. patent protection is pending.Type of Offer: Licensing
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