Material systems and methods of manufacture for auxetic foams
AssigneeThe Florida State University Research Foundation, Inc.
InventorsChangchun Zeng, Yan Li
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Abstract
A novel material for producing auxetic foams is disclosed. The material comprises a multiphase, multicomponent polymer foam with a filler polymer having a carefully selected glass transition temperature. Novel methods for producing auxetic foams from the material are also disclosed that consistently, reliably and quickly produce auxetic polyurethane foam at about room temperature (25° C.). This technology overcomes challenging issues in the large-scale production of auxetic PU foams, such as unfavorable heat-transmission problem and harmful organic solvents.
Claims29
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The method of claim 18, wherein the filler polymer comprises styrene acrylonitrile copolymer.
The method of claim 18, wherein the compressed volume of the foam ranges from about 15 percent to about 85 percent of the initial volume.
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The method of claim 18, wherein the predetermined time ranges from about 1 minute to about 4 hours.
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The method of claim 18, wherein the predetermined time is less than about 10 minutes.
The material system of claim 29, wherein the compressed gas is primarily carbon dioxide or nitrogen.
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The method of claim 18, wherein the foam has a Poisson's ratio greater than zero prior to placement in the pressure chamber and a Poisson's ratio less than zero after removal from the pressure chamber.
The method of claim 18, wherein varying a concentration of the filler polymer in the foam causes variation of mechanical properties of the foam.
The method of claim 18, wherein the pressure chamber further comprises a mold, and the flexible foam conforms to a shape of the mold after removal of the foam from the pressure chamber.
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A method for producing an auxetic foam, comprising:
- providing a flexible foam having an initial volume, the foam comprising a plurality of cells, and further comprising a soft domain having a first glass transition temperature, a hard domain having a thermal transition temperature greater than the first glass transition temperature, and a filler polymer having a second glass transition temperature greater than the first glass transition temperature and less than the thermal transition temperature;
- placing the foam into a pressure chamber and compressing the foam to a compressed volume less than the initial volume, such that the cells are deformed;
- heating the compressed foam within the pressure chamber to a temperature greater than the second glass transition temperature and less than the thermal transition temperature for a predetermined time;
- allowing the compressed foam to cool to a temperature less than the second glass transition temperature while remaining compressed in the pressure chamber;
- and
- removing the foam from the pressure chamber and fixing the cells in the deformed state.
A material system for the production of auxetic foam, comprising:
- a bulk matrix, comprising:
- a soft domain comprising a polymer chain and having a first glass transition temperature;
- a hard domain covalently or non-covalently linked to the polymer chain of the soft domain and having a thermal transition temperature greater than the first glass transition temperature;
- and
- a filler polymer dispersed in the bulk matrix and having a second glass transition temperature greater than the first glass transition temperature and less than the thermal transition temperature.
Dependencies are inferred from the claim text.