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Carbon Nanotube Composites Prepared by Ultrasonically Assisted Twin Screw Extrusion

Lewis, Todd M
http://rave.ohiolink.edu/etdc/view?acc_num=akron1405330978

Abstract Details

2014, Doctor of Philosophy, University of Akron, Polymer Engineering.
Two ultrasonic twin screw extrusion systems were designed and manufactured for the ultrasonic dispersion of multi-walled carbon nanotubes in viscous polymer matrices at residence times of the order of seconds in the ultrasonic treatment zones. The first design consisted of an ultrasonic slit die attachment in which nanocomposites were treated. A second design incorporated an ultrasonic treatment section into the barrel of the extruder to utilize the shearing of the polymer during extrusion while simultaneously applying treatment. High performance, high temperature thermoset phenylethynyl terminate imide oligomer (PETI-330) and two different polyetherether ketones (PEEK) were evaluated at CNT loadings up to 10 wt%. The effects of CNT loading and ultrasonic amplitude on the processing characteristics and rheological, mechanical, electrical, thermal and morphological properties of nanocomposites were investigated. PETI and PEEK nanocomposites showed a decrease in resistivity, an increase in modulus and strength and a decrease in strain at break and toughness with increased CNT loading. Ultrasonically treated samples showed a decrease in die pressure and extruder torque with increasing ultrasonic treatment and an increase in complex viscosity and storage modulus at certain ultrasonic treatment levels. Optical microscopy showed enhanced dispersion of the CNT bundles in ultrasonically treated samples. However, no significant improvement of mechanical properties was observed with ultrasonic treatment due to lack of adhesion between the CNT and matrix in the solid state. A curing model for PETI-330 was proposed that includes the induction and curing stages to predict the degree of cure of PETI-330 under non-isothermal conditions. Induction time parameters, rate constant and reaction order of the model were obtained based on differential scanning calorimetry (DSC) data. The model correctly predicted experimentally measured degrees of cure of compression molded plaques cured to various degrees. An apparatus for high temperature resin transfer molding (HT-RTM) was designed and built to produce PETI-8 and PETI-330/carbon fabric composite panels. Performance of the panels was tested at various temperatures. The produced panels exhibited low void content in wetted areas and had higher short beam shear properties in comparison with vacuum assisted resin transfer moldings. To investigate the environmental aspects of nanomaterials, a testing apparatus was designed and manufactured to study the effectiveness of particulate respirators at filtering CNTs. Three different grades of respirators were evaluated for their effectiveness to prevent the inhalation of CNTs. Dust masks, commonly used in a processing environment, were found to be highly ineffective at preventing the inhalation of CNTs. However, respirators with a National Institute for Occupational Safety and Health (NIOSH) rating of P95 or greater were shown to prevent the inhalation of CNTs under normal breathing conditions.
Avraam Isayev, Dr. (Advisor)
Sadhan Jana, Dr. (Committee Member)
Alamgir Karim, Dr. (Committee Member)
Shing-Chung Wong, Dr. (Committee Member)
Wieslaw Binienda, Dr. (Committee Member)
243 p.
Materials Science; Polymers
CNTs; CNT; PETI-330; PEEK; nanocomposites; carbon nanotubes; mwnts; multiwalled carbon nanotubes; Twin Screw Extrusion

Recommended Citations

Citations

  • Lewis, T. M. (2014). Carbon Nanotube Composites Prepared by Ultrasonically Assisted Twin Screw Extrusion [Doctoral dissertation, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1405330978

    APA Style (7th edition)

  • Lewis, Todd. Carbon Nanotube Composites Prepared by Ultrasonically Assisted Twin Screw Extrusion. 2014. University of Akron, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1405330978.

    MLA Style (8th edition)

  • Lewis, Todd. "Carbon Nanotube Composites Prepared by Ultrasonically Assisted Twin Screw Extrusion." Doctoral dissertation, University of Akron, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1405330978

    Chicago Manual of Style (17th edition)

akron1405330978
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© 2014, all rights reserved.
This open access ETD is published by University of Akron and OhioLINK.