Temperature-Activated Polymer

Try water it becomes ice and will do all you want!

That was surely a very witty reply. It certainly does point out the inadequacy of my original question. I should have noted that the material I am seeking needs to be a stable solid at ordinary environmental temperatures outdoors in the temperate zones of our planet. In addition I need an expansion factor of 30% or so.

Another way to accomplish the required action might be with a material that is very compressible down to about freezing and then becomes quite solid by about 28 degrees F., but this is a second choice. Again the material to meet the above environmental specs. Thank you for your response.

I doubt there is a substance in the universe, known or unknown, that would give you the 30% expansion over the negative temperature gradient you are suggesting. I could however be wrong and am interested in what others have to say about it.

I would have to concur. Maybe some of that stuff Alice had on the other side of the looking glass.

Such technology you can not expect for free. perhaps if your company has funds then talk to some technology developer or ORNL www.ornl.gov for help as they may help small industry research. Materials and technology one purchase for money. Possibilities are worked out for a need if funded. Imposible is something that is always pushed a bit to create space.

Not what I hoped to hear but thanks much for the input everyone.

For increasing the volume, the structure need to be bigger and harder and forming by itself and also rapidly and N number of times without losing property. This you can achieve using bimetal strips forming cavities in the material. In bimetal one side bending is possible with increase or decrease of temperature. How you are going to do it again is your part of the research. I have given you a possibility which sure gives you a direction.

Metal can also be replaced with similar organic material. Look for strong material - fiber which can form a force that can withstand the pressure. Each of us who starts research takes just such threads in mind and tries ideas by design.

You have posed a very nice problem. You get five points for that.

Another solution is to sense the temperature and heat the material externally or internally using embedded heaters. This thing may be easly possible and within the reach of an engineer to design a method. However it will require energy. Internal heating can prevent wastage of energy.

With absolutely no idea how this will utimately be used, I would look to existing products that are mechanically actuated based on temperature.

The two that come to mind are bi-metal elements and wax-piston motors. Both have been mass produced for automotive applications in thermostats - originally the bimetals, and recently more wax-pistons.

The wax piston requires more space (as currently developed), and requires some kind of mechanical coupling to apply the force in the opposite direction to the expansion of the wax, since you apparently want something to be pushed (rather than pulled in) as the temperature DEcreases (inverse actuation). On the plus side, the wax can be custom formulated to operate at a selected temperature range, and most are nearly solid as a polymer at near-freezing temperatures, and can apply great force over small distance.

For small size and durability, go bi-metal. The metal alloys are selected for temperature response in the range you need, with member length and attachment dependent on the actuation displacement required.

If you can run 12VDC to this as a circuit...you can always use a bi-metal as a snap-action switch that activates the circuit in a mini wax-motor with a heating element inside.

Try these guys:

www.ark-les.com/products/custom-products/actuators-wax-motors/default.html#wax

This is of interest to me--thank you very much. I will educate myself somewhat on the subject of "wax motors".

Lon

Yes, this wax motor idea is nice one.

The link is OK and I looked at noth hot and cold activated wax-motors.

Five points to this information.