G Love: Future Work/Alternative Plans

Encapsulation Process

In the design of our gloves we worked with two different phase change materials (PCM). We studied PEG and octadecane because of their melting and recrystallization properties. We tried various methods of incorporating both phase change materials into the gloves through several different encapsulation processes.

The octadecane was both made into microspheres and crushed with a mortar and pestal and put into PDMS. The goal of creating the microspheres was to increase the surface area of the PCM. We found, however, that our method for making microspheres needs improvement because it takes a great deal of effort to produce a relatively small number of microspheres. When the octadecane is crushed, we can easily get the 5 grams of octadecane our calculations deemed necessary to produce enough heat to keep the hand comfortable. One key concern is the thermal properties of the PDMS. The PDMS is an insulating material which may keep the heat produced from the octadecane from exiting and thus not heating the hand. Future research is necessary to find out about other potentially good plastics or rubbers to encapsulate the octadecane. It would also be a good idea to see it would be beneficial, perhaps, to seal the octadecane in pouches like we did with the PEG.

We attempted to melt PEG and PP together, but found that the high melting point of PP made this impossible given our facilities. Ideally, future work would be done to test out the procedures for extrusion of PEG and PP described in a paper published by a group of researchers (referenced below). PEG and LDPE were then melted together, again without much success. Eventually, the PEG was heat sealed with an iron in LDPE bags in shapes that could be inserted into the pockets in the lining of the gloves. A better method of encapsulating PEG is necessary.

Further DSC testing is necessary to observe the effects of melting and recrystallization and get a more accurate idea of temperature range that occurs in this process.

Testing of PDMS with a thermally conductive material should be done. This should be done in an attempt to increase thermal conductivity and therefore glove efficiency. This was not done in our experimentation because it was thought that it would be more efficient to have the maximum amount of PCM possible in the PDMS. It would still be worth trying in the future.

The PCM field testing should be done in a freezer in order to actually compare it to the wire testing that was done in the freezer. This was not done because the amount of time a battery will heat a wire in relation to the amount of time the phase change material gives off heat differs by hours.

Additional field testing of the PCM should be done using real people wearing the gloves in a cold environment. Then we will be able to see how the gloves actually work when hands are in the gloves. It would be good to find out if there is even enough heat for remelting to occur. Some form of heat model hand could be used to heat the gloves so people do not have to sit in a cold freezer for long periods of time.

Reference: “Novel Desiccants Based on Designed Polymeric Blends” Edith Mathiowitz, Jules S. Jacob, Yong S. Jong, Thab M. Hekal, William Spano, Rene Guemonprez, Alexander M. Klibanov, Robert Langer Accepted 21 April 2000

Incorporation of Wire into the Gloves

The wires were connected into the gloves using thread and sewing small bits of the wire onto the inner lining at various intervals along the length of the wire. A better method of incorporating the wire securely into the gloves should be studied. A way to weave the wire into the lining in the glove would be one way this could be accomplished. Using fabric with wires already incorporated into it is also something that should be investigated.

Ease of Access to Recharge Battery

The batteries have been attached to the Ni:Cr wire using small connectors that can be attached and detached. Once the wires are detached, the battery can be connected directly to a power source to be recharged. While this works for a prototype, this is not an ideal way to recharge a battery. The complexity would be a deterrant for the average consumer. Further work with the batteries is necessary to create a product that is easier for the everyday consumer to use.

On/Off Switch

Currently, there is no way other than disconnecting the wires from the battery to stop the battery from running. Hence, further work would include incorporating a small on/off switch into the gloves. The switch would need to be coincide with the goal of our project—to create a light-weight, efficient glove—and hence, the switch would have to be relatively small and not inconvenience the wearer.

Insulation of Wire

In our prototype, we were able to get the teflon tubing that we desired. However, we found it next to impossible to slide the tubing onto the wire. We had to cut the tubing into sections and slide them on one section at a time. A better method of insulating the wire is necessary. This may be as simple as ordering wire with teflon tubing already on the wire, but we found, given the time restraint of the project, that ordering teflon covered wire of the appropriate diameter would not be possible. Once the new wire and insulator is found, testing of the wire should be done to determine how ideal or non-ideal the properties of the wire prove to be.

Updated 5/14/02