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.
Claims28
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, a hard domain, and a filler polymer;
- 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;
- exposing the compressed foam within the pressure chamber to a compressed gas, and maintaining the pressure chamber at a predetermined temperature and predetermined pressure for a predetermined time;
- dissolving at least a portion of the compressed gas into the filler polymer and reducing a glass transition temperature of the filler polymer such that the filler polymer transitions from a glassy state to a rubbery state;
- and
- allowing the foam to reach atmospheric pressure and removing the foam from the pressure chamber such that the filler polymer transitions from the rubbery state to the glassy state and fixes the cells of the foam in the deformed state.
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, a hard domain, and a filler polymer;
- 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;
- exposing the compressed foam within the pressure chamber to carbon dioxide at a predetermined temperature and predetermined pressure for a predetermined time;
- dissolving at least a portion of the carbon dioxide into the filler polymer and reducing a glass transition temperature of the filler polymer such that a shape of the filler polymer transitions from generally spherical to generally ellipsoidal;
- and
- allowing the foam to reach atmospheric pressure and removing the foam from the pressure chamber such that the filler polymer retains the generally ellipsoidal shape thereby fixing the cells of the foam in the deformed state.
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.