Integration and Transient Shear-Thickening Effects of Carbon Nanotubes and Carbide

Nanoparticles in a Polymer Matrix

John ConleyAdvisor: Dr. Ajay Malshe

7/20/09

Background Information• Carbon Nanotubes

– Discovery by Iijima in 1991– Unique properties due to size and structure

• Conductive, strong, lightweight, etc.

– SW, DW, and MW varieties• SW better for nanocomposites

• Polymer– Ultra High Molecular Weight Polyethylene

Goals1. Improve nanotube/particle integration and

loading to improve mechanical properties (strength, hardness, etc.)

2. Characterize shear-thickening effect of nanotubes/particles in polymer matrix

3. Combine loaded polymer with other materials to create prototype complex material

First Phase: Synthesis

Source: Dr. Ajay Malshe

+

+ CNTs = . . .

Results

Second Phase: Testing/Characterization• Testing

– Transmission Electron Microscopy, for surface morphology.– Nanoindentation, for hardness.– Nanoindentation, for storage modulus.– Tensile testing, for tensile strength.– Tensile testing, for Young’s modulus.– Izod or Charpy testing, for impact hardness

• Characterization– Analyze mechanical properties during dynamic and static

loading to determine characteristics of shear-thickening effects

Results• Nanoindentation

Neat UHMWPEUHMWPE loaded with ~20% by weight CNTs

Young’s Modulus 0.69 GPa 1.68 GPa

Hardness 92.1 MPa 493 MPa

Future Work

New Process Idea• Skip complicated wet phases and associated

processes– Filtration, drying, etc.

• Utilize powdered materials and vibrator plate to skip straight to hot press

• Many benefits– Easier, cheaper, safer, faster, simpler, unique

Proposed Method: Dual Powder Sintering

Plans• Continue phases I and II– Manufacture multiple samples of nanocomposite• CNT/UHMWPE composite with new, purer UHMWPE

phase from TiconaUSA• Begin testing of dual powder sintering synthesis

method for carbide nanocomposite

– Complete parameter matrix– Analyze with more advanced testing equipment

like TEM or SEM– Validate results with macroscale testing

Third Phase: Molecular Dynamics• Empirical models for fiber in composite matrix

– Equivalent-continuum modeling method• Traditional fiber composite models do not apply• Must take into account large interfacial area relative to polymer

matrix volume• Must take into account secondary forces such as VdW forces

• Nanocomposite models– Polymer matrix/CNT – Polymer matrix/CNT interfacial modeling– Van der Waals modeling– σ-ε behavior

• Analyzed by comparing to rule of mixtures

Acknowledgements• Steven Wehmeyer

– Supply of purified CNTs• Ranjit John

– Supply of CNTs, technical advising• Dmytro Demydov

– Primary advising• Jason Bailey, Mohammed Chowdhury, Parash Kalita, Anoop Samant,

Corey Thompson, Wenyang Zhang– Technical advising and assistance

• Joshua Wilson– Administrative assistance

• NanoMech– Equipment loan

References• R. Andrews, A. Berkovich, J.C. Hower, D. Jacques, & T. Rantell.

“Fabrication of Carbon Multi-wall Nanotube/Polyer Composites by Shear Mixing.” University of Kentucky, Center for Applied Energy Research.

• W.C. Oliver and G.M. Pharr. Measurement of hardness and elastic modulus by instrumented indentation: Advances in understanding and refinements to methodology. J. Mater. Res. 19 (2004), 3.

• Wetzel, Eric D. et al. "Protective Fabrics Utilizing Shear Thickening Fluids." 2004.

• Yuezhen Bin, Mayuna Kitanaka, Dan Zhu, and Masaru Matsuo. Department of Textile and Apparel Science, Faculty of Human Life and Environment, Nara Women’s University, Nara 630-8263, Japan.

Your comments, questions, and advice are appreciated.