Tailoring the Poisson Ratio: Design Concepts for New Polymeric Materials
Abstract
This report describes work toward the establishment of design criteria for producing polymeric materials having a negative Poisson ratio. This unusual mechanical behavior is also known as auxetic behavior and is characterized by a material getting fatter when stretched. Our approach deals with a molecular-scale concept by which a nematic liquid crystalline field orients rigid rods in a main chain polymer - some of which are attached to the chain at lateral positions along the rod as opposed to attachment at the ends of the rods (terminal attachment). The nematic field-induced parallel orientation of all rods is subsequently overcome by a mechanical field when stretched. The side-attached rods will then orient roughly normal to the stretch direction resulting in an increase in the interchain separation and to an auxetic response. We have made model compounds to examine this concept; a series of nematic polymers having end- and side-attached rods; and crosslinked nematic polymers having end- and side-attached rods. X-ray data is consistent with our postulated effect and mechanical testing has shown a strong sensitivity to the molecular structure.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 01, 2003
- Accession Number
- ADA419506
Entities
People
- Anselm C. Griffin
Organizations
- University of Southern Mississippi