Preferential nanoreinforcement of thermoplastic polyurethane elastomers with dispersed nano-clay

It is difficult for scientists to engineer elastomeric materials that are both strong and tough like spider dragline silk. Inspired by the morphology of spider dragline silk and motivated to develop strong, tough, elastomeric polyurethanes to be used in soldier applications I have prepared polyurethane/clay nanocomposites. Polymer/clay nanocomposites have exhibited great potential for providing enhanced and possibly-tunable thermomechanical behavior. However, the biggest challenge facing advances in polymer/clay nanocomposites is the complete dispersion of nano- clay within the polymer matrix due to thermodynamic and kinetic limitations. A novel solvent exchange method to fully exfoliate and disperse discotic smectic clay, Laponite (diameter = 25 nm, thickness = 1 nm), in three thermoplastic polyurethane elastomers (TPUs) -- Elasthane 80A, HDI-PTMO PU, and PU-1-33 -- has been developed. This clay was selected because the diameter of one platelet is similar to the lateral dimension of a single hard-domain in block-polymeric TPU. WAXD, TEM, and AFM phase imaging of cast films following solvent exchange show that the nano-clay is well dispersed in the TPUs. Uniaxial mechanical testing showed that as much as a 23-fold increase in elastic modulus, 100% increase in toughness, and 50% increase in strength can be achieved without a reduction in extensibility when Laponite is added to Elasthane. Furthermore, the heat distortion temperature of the Elasthane can be increased from 101⁰C to more than 200⁰C, as measured by DMA, when 20 wt% Laponite is added.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Mechanical Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2005

Author dc:creator

• Liff, Shawna M. (Shawna Marie)

Advisor dc:contributor.advisor

• Gareth H. McKinley.

• Mechanical Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/32356

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/32356