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ETD. Xinting Wang.pdf (7.69 MB)

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NEW SYSTEMS FROM THE FORCED ASSEMBLY CO-EXTRUSION PROCESS

Wang, Xinting
http://rave.ohiolink.edu/etdc/view?acc_num=case1607104088439343

Abstract Details

2021, Doctor of Philosophy, Case Western Reserve University, Macromolecular Science and Engineering.
Development of continuous micro-/nano-fibrous composite tapes was achieved by a novel forced assembly co-extrusion process. The co-extrusion process was combined with 18 vertical and 5 horizontal multipliers, producing a unique structured tape which comprises a cross sectional matrix of 8192 x 32 individual polymer A and B domains. The tape could be post oriented to achieve enhanced mechanical properties due to their continuous feature in the extrusion direction. The domains could be mechanically separated by high pressure water jet if separating layer C is introduced before the horizontal multiplication. Different systems were developed for different applications in this work. In Chapter One, polypropylene/high-density polyethylene (PP/HDPE) and polypropylene /polyamide 6 (PP/PA6) systems with polystyrene (PS) as the separating layer were studied for alkaline battery separator applications. PP/HDPE and PP/PA6 dual-component fibrous separators were fabricated by delamination of oriented PP/HDPE/PS and PP/PA6/PS tapes which were produced from force assembly co-extrusion. The separators had average pore size of 10 μm, high porosity and high surface area. The electrolyte absorption (KOH uptake) of PP/HDPE separators and PP/PA6 separators were almost 3 times higher than that of commercial separators. The battery performance of the PP/HDPE separators and the PP/PA6 separators were evaluated in a coin cell battery configuration. The charge-discharge efficiency of coin cells made from the PP/PA6 separator was found to be 6% higher than the commercial separators. In Chapter Two, the orientation of PP/HDPE tape system was studied because both polymers could be oriented into strong fiber. The structure of the PP/HDPE tapes consists of co-continuous PP and HDPE domains which are elongated in the extrusion, forming fiber-like structure with individual domain thickness of 200 nm to 500 nm in the extrusion direction. This unique structure creates extra-large contact area between the two components. AFM images suggest strong interactions between incompatible PP and HDPE. PP and HDPE crystallize at the same temperature, indication epitaxy between the two components. Orientation near the melting point of HDPE at 130oC is made possible because of the enhanced adhesion due to epitaxial crystallization and large interactive area between PP and HDPE. Modulus, tensile strength and orientation factor increase as draw ratio increase. Existence of shish-kebab like morphology in oriented tapes at different draw ratios is indicated by the two melting peaks. After one-step orientation at 130oC to draw ratio of 25, the moduli of oriented tapes increase to around 10 GPa and the tensile strength increased to about 540 MPa. These oriented tapes are stiffer and stronger than various commercial tapes and did not fibrillate during orientation. In Chapter Three, poly (ethylene-co-methacrylic acid) sodium-neutralized ionomer (Surlyn 8940) fibers were produced from Surlyn/PS system. The PS matrix material were removed by toluene extraction to yield independent Surlyn fibers. The tensile properties of Surlyn fiber strands were studied under different strain rates. Surlyn fibers were oriented to 300% strain at different temperatures to study the effect of orientation on the tensile properties. The oriented Surlyn fibers were annealed after orientation to further enhance the mechanical properties. Further drawing of these oriented fiber mats to a draw ratio of 4 at 60oC followed by annealing at 60oC can afford moduli in excess of 350 MPa and tensile strengths in excess of 70 MPa.
Eric Baer (Committee Chair)
Lei Zhu (Committee Member)
Gary Wnek (Committee Member)
James Anderson (Committee Member)
110 p.
Plastics; Polymers

Recommended Citations

Citations

  • Wang, X. (2021). NEW SYSTEMS FROM THE FORCED ASSEMBLY CO-EXTRUSION PROCESS [Doctoral dissertation, Case Western Reserve University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=case1607104088439343

    APA Style (7th edition)

  • Wang, Xinting. NEW SYSTEMS FROM THE FORCED ASSEMBLY CO-EXTRUSION PROCESS. 2021. Case Western Reserve University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=case1607104088439343.

    MLA Style (8th edition)

  • Wang, Xinting. "NEW SYSTEMS FROM THE FORCED ASSEMBLY CO-EXTRUSION PROCESS." Doctoral dissertation, Case Western Reserve University, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=case1607104088439343

    Chicago Manual of Style (17th edition)

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This open access ETD is published by Case Western Reserve University School of Graduate Studies and OhioLINK.