CAREER: Research and Education on Multi-Scale Structure Development in Chaotic Mixing of Polymers

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This Faculty Early Career Development (CAREER) award focuses on research and education on the subject of evolution of multi-scale structures of polymeric material during processing. The influence of these evolving structures on mechanical, electrical, and thermal properties in chaotic mixing of miscible and immiscible polymers and nanofiller systems under controlled conditions of strain rates and temperatures is experimentally investigated. Chaotic mixing offers the following highly desirable attributes: (a) mixing occurs by both shear and extensional flow components, (b) polymer-polymer or polymer-filler interfacial areas are created at exponential rates, with much less energy consumption for the same degree of mixing than in conventional extrusion processes, (c) self-similar mixing microstructures are formed by repeated stretching and folding of the interfaces, showing nested striations, droplets, or layers of one polymer in the other leading to potential morphologies so far not achieved in conventional single and twin-screw extrusion schemes and (d) mixing uniformity is achieved with retention of self-similar microstructures, as opposed to randomization in conventional single- and twin-screw extruders. Rapid interfacial area generation will expedite reactions between functional polymers in reactive processing and in compatibilization in addition to rapid reduction in dispersed domain sizes. The self-similar microstructures produced will offer preferred orientation of the crystallites/dispersed phases for augmentation of anisotropic electrical, mechanical, and chemical properties and will act as tools for creating unusual morphologies for design of polymer products with tailored properties. The study to be undertaken using twin-rotor chaotic batch mixer and continuous chaotic mixer will yield low cost, rapid, and energy-efficient mixing technology for scale-up studies, optimization of existing products, and process development in association with industrial partners. The education program will provide hands-on polymer education to high school and undergraduate students, including minority, through summer research and senior research projects and through participation in seminars and presentations. A new course will be developed on the applications of chaotic mixing in materials processing for graduate students and industry, which will draw heavily from the proposed research activities. In addition, web based course modules will be designed on rheology and polymerization reactor engineering to reach a much larger body of students outside conventional classrooms.