Skip to Main Content
 

Global Search Box

 
 
 
 

ETD Abstract Container

Abstract Header

Manufacturing of High Performance Polymer Nanocomposites Containing Carbon Nanotubes And Carbon Nanofibers Using Ultrasound Assisted Extrusion Process

Abstract Details

2010, Doctor of Philosophy, University of Akron, Polymer Engineering.

The major objective of this study was to investigate the effect of ultrasonic treatment on the state of dispersion and properties of carbon nanotubes (CNTs) and carbon nanofibers (CNFs) in polymer matrices. In order to achieve this objective, an ultrasonic single screw extruder operating at a frequency of 20 kHz and an amplitude of upto 10 μm and an ultrasonic twin screw extruder operating at a frequency of 40 kHz and an amplitude of upto 6.0 μm, were used to process highly viscous materials and disperse these nanofillers homogeneously in a polymer matrix at residence times of order of seconds. High temperature thermoplastic resins including polyetherimide (PEI), liquid crystalline polymer (LCP) and polyetheretherketone (PEEK) were used. Multiwalled carbon nanotubes (MWNTs) and CNFs were used as reinforcing fillers. The effect of nanofiller loading and ultrasonic amplitudes on rheological, mechanical, electrical, thermal and morphological properties of the nanocomposites was studied. Ultrasonic treatment showed a tremendous decrease in die pressure. Morphological studies showed that ultrasonic treatment improved dispersion of CNFs and CNTs in polymer matrices.

PEI/CNFs and PEI/MWNTs nanocomposites were prepared using ultrasound assisted single and twin screw extruder, respectively. A permanent increase in the viscosity, storage and loss modulus and decrease in tan δ was observed with ultrasonic treatment. Ultrasonically treated PEI/CNFs nanocomposites showed a decrease in electrical percolation threshold value as compared to the untreated ones. Breakage of CNFs was observed primarily due to extrusion process alone. In case of PEI/MWNTs nanocomposites, percolation threshold value was found to be between 1 and 2 wt% loading of CNTs for both treated and untreated samples.

LCP/CNFs nanocomposites were prepared using ultrasound assisted twin screw extruder with separate feeding of CNFs in the polymer melt. In contrast to behavior of PEI/CNFs and PEI/MWNTs nanocomposites, the rheological behavior of LCP/CNFs nanocomposites practically was not affected with the ultrasonic treatment due to a reduction in fibrillation of LCP matrix in the presence of CNFs. Similar to PEI/CNFs nanocomposites; ultrasonically treated samples showed a decrease in the electrical percolation threshold value as compared to the untreated ones. Due to reduction in fibrillation of LCP no improvement in the mechanical properties was observed on addition of CNFs. After introducing the orientation by fiber spinning of LCP/CNFs nanocomposites, a tremendous increase in the mechanical properties of fibers was observed with increase in the draw down ratio.

PEEK/MWNTs nanocomposites were prepared using ultrasonic single screw extruder. In contrast to PEI/CNFs and PEI/MWNTs nanocomposites, ultrasonically treated PEEK/MWNTs nanocomposites showed decrease in the complex viscosity, storage modulus. Loss modulus and increase in tan δ as compared to untreated ones. This could be due to the competition between increased dispersion of CNTs and a possible degradation of the polymeric chains in the presence of CNTs and a possible reduction of CNTs length on application of ultrasound. Due to above effects, ultrasonic treatment reduced the physical contacts between the CNTs and hence increased the volume resistivity near the percolation threshold. No degradation of pure PEEK matrix upon application of ultrasound was observed.

Avraam Isayev, Dr. (Advisor)
Erol Sancaktar (Committee Chair)
Kevin Cavicchi (Committee Member)
Darrell Reneker (Committee Member)
Zhenhai Xia (Committee Member)
260 p.

Recommended Citations

Citations

  • Kumar, R. (2010). Manufacturing of High Performance Polymer Nanocomposites Containing Carbon Nanotubes And Carbon Nanofibers Using Ultrasound Assisted Extrusion Process [Doctoral dissertation, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1291639408

    APA Style (7th edition)

  • Kumar, Rishi. Manufacturing of High Performance Polymer Nanocomposites Containing Carbon Nanotubes And Carbon Nanofibers Using Ultrasound Assisted Extrusion Process. 2010. University of Akron, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1291639408.

    MLA Style (8th edition)

  • Kumar, Rishi. "Manufacturing of High Performance Polymer Nanocomposites Containing Carbon Nanotubes And Carbon Nanofibers Using Ultrasound Assisted Extrusion Process." Doctoral dissertation, University of Akron, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=akron1291639408

    Chicago Manual of Style (17th edition)