SBIR Phase I: Die Design Software for Polymer Coextrusion Including Layer Rearrangement Due to Viscous Encapsulation and Secondary Flow

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This Small Business Innovation Research (SBIR) Phase I project aims to develop software for an accurate simulation of polymer co-extrusion. During co-extrusion, different polymers are extruded simultaneously through a single die. Coextruded plastic parts combine the functionalities and benefits of several polymers into a single multi-functional product. Since the polymer layers get redistributed as they flow through a die, control of polymer distribution in coextruded products is difficult. Even though use of software is critical for optimizing the process, die designers in plastic industry rarely use commercial co-extrusion software because these packages cannot simulate multilayer flow in complicated co-extrusion die geometries, and also fail to capture complex material behavior of polymers. A unique algorithm, called mesh partitioning technique, which will be employed in the new co-extrusion software, will allow simulation of any complex co-extrusion system. A viscoelastic equation will be used to simulate co-extrusion. Incorporation of viscoelastic effects in co-extrusion simulation is important to accurately capture the rearrangement of polymer layers as different polymers flow together in a co-extrusion die. Accuracy of the software will be verified using the experimental data in the literature. New experiments will be conducted to identify the mechanism behind polymer layer rearrangement during co-extrusion. The commercial potential of this project is complete elimination of the trial-and-error approach currently being used to design co-extrusion systems, which will cut the time-to-market of coextruded products by over 30%. Many different types of companies in plastic industry, including material suppliers, plastic part manufacturers and die manufacturers, will be able to cut cost and increase revenues using this software. The software, which will be developed in this project, will also enhance the scientific understanding of the root cause behind various complexities, such as encapsulation of higher viscosity polymer by less viscous polymer, and instability of the interface between adjacent polymer layers during co-extrusion. Even though such complexities are commonly observed in co-extrusion, the driving mechanisms behind these complex phenomena are still not understood completely.