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Examining the Effectiveness of Different Mixing Elements in the Twin Screw Compounding of Liquid Crystal Polymer and Polypropylene

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2018, Master of Sciences (Engineering), Case Western Reserve University, Macromolecular Science and Engineering.
Thermotropic Liquid Crystalline Polymers, which are materials made up of semi rigid rod-like molecules, have this unique property of orienting themselves during flow. This results in the formation of a very ordered melt phase which gives these materials a plethora of superior properties like high tensile modulus, good chemical resistance, very high thermal stability, flame retardant characteristics, dimensional stability etc. However, their cost prohibits their wide scale use and limits it to niche applications. This has engendered a lot of interest in the preparation of Thermoplastic/Liquid Crystal Polymer blends. Moreover, the fact that Liquid Crystal Polymers tend to reduce the melt viscosity, making the blend easier to process, is an added incentive in addition to their properties. Extension dominated flows have been long known to be more efficient in mixing as compared to shear dominated flows. Exploiting this concept, Carson and et al. at Case Western Reserve University have developed new mixing elements for the Twin Screw Extruder. These elements were proven to impart extensional forces as opposed to the shear forces imposed by the Kneading Blocks, resulting in better dispersive and dissipative mixing. This thesis aims to use these novel extensional mixing elements on a system of Polypropylene and Liquid Crystal Polymer compatibilized by a compatibilizer, to enhance mechanical and thermal properties of Polypropylene on addition of a low quantity of Liquid Crystal Polymer. Furthermore, this research also intends to compare the extensional mixing elements to the kneading blocks, which are the industry standard. All the extrusions were carried out on a co-rotating twin screw extruder, at two different temperatures of 285-295 °C and 220-230 °C. The purpose of using two different temperatures was to melt the Liquid Crystal Polymer to prepare blends in one case, whereas to keep it a solid and prepare composites in the other case.
João Maia (Advisor)
David Schiraldi (Committee Member)
Mike Hore (Committee Member)
110 p.

Recommended Citations

Citations

  • Agrawal, A. (2018). Examining the Effectiveness of Different Mixing Elements in the Twin Screw Compounding of Liquid Crystal Polymer and Polypropylene [Master's thesis, Case Western Reserve University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=case1512742062745962

    APA Style (7th edition)

  • Agrawal, Akash. Examining the Effectiveness of Different Mixing Elements in the Twin Screw Compounding of Liquid Crystal Polymer and Polypropylene. 2018. Case Western Reserve University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=case1512742062745962.

    MLA Style (8th edition)

  • Agrawal, Akash. "Examining the Effectiveness of Different Mixing Elements in the Twin Screw Compounding of Liquid Crystal Polymer and Polypropylene." Master's thesis, Case Western Reserve University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=case1512742062745962

    Chicago Manual of Style (17th edition)