Electronic Notebook

Mon 13 May 02

• Completed DSC testing of final PCM samples. Tested three samples: PEG in PE, ground octadecane in PDMS, octadecane microspheres in PDMS. Click here for results of the PEG in PE measurement. Surprisingly, neither of the octadecane samples in PDMS showed any phase change whatsoever. It is possible that something went wrong during measurement because when a virtually identical sample of ground octadecane in PDMS was run on April 26, a very significant change was noted between 26 C and 29 C with a latent heat of approximately 90J/g.
• Completed final poster. This will be taken to Kinko's tomorrow.

Fri 10 May 02

• Tiffany left for Italy this morning, to present her Course 3 Thesis Research at the Gordon Research Conference on Magnetic Nanostructures: I sent a template of the poster design to everyone. Good luck finishing up this last week. I am proud to have been a part of such a hard-working group.
• It was decided to abandon the idea of making a PE/PEG sheet in the hot press. After consultation with Professor Rubner and considering the results of trying to melt the two materials together, we realize that the chances of success would have been extremely small and we feel that our time the next few days would be better spent focusing on analyzing our other results and putting together our final presentation.
• A new sample of PEG/PE was made for the final DSC test Monday.

Thurs 9 May 02

• SEM images of the last batch of octadecane microspheres were taken. Because the SEM was charging up and the pictures were very dark, pictures were also taken using the optical microscope in 8-003. Although it was difficult to tell because it looked like some microspheres had clustered together, the average size appeared to agree with the SEM results. Click here for results.
• Took optical microscope pictures of the octadecane embedded in PDMS, the PEG in PE, and the two failed attempts to melt the PEG and PE together using the microscope in Professor Ortiz's lab. Click here for results.
• The three teflon sheets ordered from lab supplies two weeks ago finally arrived today.
• The three gloves which Colin's mother sewed arrived today. They look great!
• Conducted final heat testing on the three finished gloves in order to select the best candidate. The three gloves tested were one with the NiCr wire heating element, one with the PEG in PE baggies placed in pockets, and one with octadecane in PDMS placed in pockets. Results to come soon.
• It turned out that the sample of PEG in PE we had made for DSC testing was too large to fit in the pan. Therefore this test will have to be postponed until Monday. However, all other lab work was finished today.

Tues 7 May 02

• Because the teflon sheets still had not arrived (it turns out they were shipped to the wrong address) a second attempt was made at melting together then PEG and PE, this time without the dichloromethane. Again, this proved to be very difficult. At first the beaker with polymer was placed in water however because the melting temperature of polyethylene is actually slightly above 100 C, it had to be removed. At this point the PE and PEG started to burn slightly and began turning slightly brown. While they did both melt, the polyethylene never became completely liquid and the PEG immediatly separated out every time the beaker was removed from the heat. Finally, the polymers began to turn even browner and were removed from the heat. A few seconds later, they burst into flames. While they went out very quickly, it was decided to abandon this approach.
• For the final gloves, two sets of PCMs were created based on the most successful prototypes. One consisted of 5g octadecane embedded in PDMS resin. The second was 7g of PEG heat sealed in low density polyethylene bags. Click here for processing details of octadecane and here for PEG.

Friday 3 May 02

• The low density polyethylene in dichloromethane still had not dissolved. It was therefore decided to see if heating the solution would help. One gram of PEG was also added. The dichloromethane evaporated out very quickly, leaving behind just the two polymers. Although they did melt together, every time they would be removed from the heat they would separate almost immediately because the polyethylene would harden so much faster than the PEG. They also appeared to turn slightly brown.
• The fabric and instructions for the final gloves were shipped to Colin's mother. She will sew the gloves using the same patterns we used for the prototype and sew pockets into them for the phase change materials and battery/wires.

Thurs 2 May 02

• Kristin and Bushra had planned on trying to use the hot press (now fixed) in an attempt to press an 80:20 PP:PEG mixture together into a flat sheet. Ideally extrusion would be performed to do this, but we lack facilities. This could not be done, however, because the teflon sheets that were ordered last week have not arrived. Tim Doyle has contacted VWR for us on why they have not arrived yet. We will hopefully be able to at least try this next week. We attempted to melt the PP on a hot plate but only succeeded in fusing the bottom pieces of PP together in the beaker. The temperature on the hot plate was a bit above 100C, but the melting point of PP is 160, which is a higher than we feel comfortable heating the hot plate. We heated it under a hood with the aid of Erin.
• Erin suggested that we try to dissolve LDPE (low-density polyethylene) in Dichloromethane. We have placed ~3-4grams of a cut up plastic baggie into a beaker with Dichloromethane and left it stirring overnight. If the polymer dissolves, we will mix some PEG into the mixture since PEG also dissolves in Dichloromethane. Then, the solvent will be evaporated off, which should, ideally leave us with a resin of PE with PEG in it.
• Kristin took a few PE baggies and put some of the PEG into them in relative shapes and sizes that could be inserted in the pockets of gloves. She then used the edge of an iron to heat and seal the PEG into the plastic bags. This worked remarkably well. A nice, clean seal is made and the only problem is that the melting must be done quickly or the PEG melts and begins to ooze into unwanted areas.
• A small amount of PEG was placed in between two laminating sheets to see if the PEG could be sealed in plastic by this method, however, the sheets are pulled through the laminating machine and the PEG quickly spreads throughout the plastic because of the heat. There is no way to control this, unfortunately. Hence, we will not be using a laminator, but will continue to look at sealing the PEG in between two plastic sheets. This is not the most "processed" method, but we can get the amount of PEG necessary to provide the heat needed in the gloves and since we cannot extrude the PEG/PP, we have been trying to look at the other options accessible to us at this time.

Tues 30 April 02

• Today we had planned to use the hot press to make the polypropylene/PEG sheet. Unfortunately, it was broken. At the suggestion of Erin Lavik, we decided to try dissolving the two materials to see if they would mix effectively that way. The only common solvent found that was available to us was methylene chloride, however it was unclear exactly how soluble the polyproylene would be in this. A small amount of polypropylene was placed in methylene chloride overnight however it did not dissolve. Also at the suggestion of Erin Lavik, we decided to try using low density polyethylene as another possible encapsulant. High density polyethylene is often used as an encapsulant for PCMs however it would have been just as difficult to process as the polypropylene. Centrifuge tubes are commonly made out of polyethylene so some of these were obtained from lab supplies. Unfortunately it turns out that the new centrifuge tubes are actually made out of PET, not polyethylene, so this did not work either.

Fri 26 April 02

• DSC testing of samples of octadecane embedded in PDMS resin processed Thursday of last week. Results.

Tues 23 April 02

• Colin discharged the voltage of the Li-Polymer Battery. 100 cm of the Ni-Cr wire was attached to the battery, and then measured the voltage in intervals until the voltage was ~0. Unfortunately, Prof. Ceder said the discharge should have stopped earlier, because overdischarge could easily occur with how far we allowed the discharge to proceed. Note of the discharge was taken by observing the voltage meter. Click here for results.
• Tiffany had reserved time on the DSC to test the samples of octadecane embedded in PDMS that was processed last Thursday. Tim McClure was not in lab today, and since she's not an official self-user of the DSC, she was not allowed to use it. Another time must be scheduled.
• Bushra and Tiffany successfully filtered the octadecane microspheres made last Thursday using the new filters. We believe that our failed attempts to filter last Friday were caused by degredation of the filters over time. The new filters worked today. We planned to freeze the microspheres using liquid nitrogen, but Erin's lab ran out of liquid nitrogen. The microspheres will be frozen and placed in the lyophilizer on Friday. SEM images of these microspheres will be taken.
• Kristin planned the processing procedure for embedding PEG into polypropylene. A dry mixture of PEG and polypropylene will be made, with no more than 20% PEG. A hot press in Erin Lavik's lab will be utilized for melting the mixture and forming it into a flat sheet. Teflon sheets will be placed on the two plates of the hot press.
• Colin and Jeff tried to solder the wires to the leads of our batteries, which are just very delicate pieces of sheet-like, metal. We were warned by Prof. Ceder that the heat from soldering may damage the battery. Joe Parse suggested that we use a heat sink during the soldering process. With the recommendation of Prof. Ceder, the battery was discharged before an attempt at soldering was made. Soldering of wire to the copper lead was done with little difficulty. However, the silver lead was more difficult to work with. Another form of attachment is necessary.
• Tiffany worked on finalizing the heat transfer calculations. It is nearly finished with the exception of using more accurate thermal conductivity values for the fabric and adding an appropriate diagram. This heat transfer calculation, in its finalized form, will be presented on the design page.

Mon 22 April 02

• Took microcope pictures using the microscope and computer imaging technology in Prof. Christine Ortiz's Lab 12-065. Pictures of the crushed octadecane embedded in the silicone, which we made on April 18 were taken at Magnification levels of both 2,5x and 10x. The pictures show us the large varying sizes of fragments, and also give insight into the spread of octadecane within the silicone. There are many areas where it was impossible to get a clear image of all areas because some fragments were further from the rubber surface than other fragments. After looking at the silicone, it appeared that because the PDMS solution has a greater density than water, the octadecane floats in the solution and did so while setting meaning many pieces of octadecane appeared to be almost coming out of the upper surface of the silicone. The results are shown here

Fri 19 April 02

• Attempted to filter the new batch of octadecane microspheres, but ran into problems. Every time we turned on the vacuum to filter the microspheres, the pressure would burst holes in the filter paper (even when the vacuum was turned on VERY slowly). We are not sure why this happened, since we were following the same procedure as last time (same filters, same vacuum line, etc.). Professor Irvine suggested that some type of organic solvent could be eating a hole in the filters. We bought two larger filters from lab supplies to see how they work. One possibility is to try the vacuum line in his lab, which is very weak. We may also try an entirely different type of filter if that fails.

Thurs 18 April 02

• Fabricated another set of octadecane microspheres, using a slightly revised procedure to chill the solution and make a larger quantity. Click here for revised procedure.
• Experimented with embedding octadecane directly in PDMS without first making microspheres. This was done by grinding the octadecane into small particles using a mortar and pestle. More details and DSC testing on these samples to come soon.
• Tested the surface temperature of the Ni-Cr wire to see if it would reach the ignition temperature of cotton, fleece (both 250 C), or the insulation. The first piece was only 30 cm long, and reached a temperature of 240 C at 3.7 V. It burned the paper and the fabric. Conclusion: 30 cm is bad. The next length of wire was 100 cm long, and it only reached a temperature of 60 C. Conclusion: 100 cm = good. More details to come soon.
• Tested the resistances of the switches as a function of temperature. Good news: the resistance is zero until it switches. At that point, the Ameter/Voltmeter gave an error sign, meaning the resistance is greater than MegaOhms.
• Also tested the current through the switches as a function of temperature. I set the current to .43 A (the current we'll be using). Once the switch hit the switch temperature, the current dropped to .0012 A. This means we lose .000012 W of power after the switch flips.

Wed 10 April 02

• Tested embedded octadecane microspheres in DSC. Compared to a piece of PDMS resin with no microspheres. Click here for results.
• Sewed five gloves out of the following materials: fleece (100% polyester), flannel (100% cotton), 80% cotton/20% polyester blend, and a 20% cotton/80% polyester blend. Two pairs of fleece gloves were made. A battery was sewn into a pocket on one of the fleece gloves and the heating element was sewn to the outside of the flannel gloves (the flannel would serve as an inner lining with another layer of material on top of the heating element.
• Completed a heat transfer experiment on the five gloves to compare their heat transfer coefficients. The fleece gloves had the lowest H and were therefore the best insulator. Complete results available soon.

Tues 9 April 02

• Erin Lavik helped us take SEM images of the octadecane microspheres. It appeared that the octadecane may have melted and recrystallized during fabrication. Click here to see the images.
• Embedded octadecane microspheres in PDMS resin. Click here for procedure.

Thurs 4 April 02

• Met with Professor Irvine about incorporating the microspheres into the gloves. One thing he suggested was trying to incorporate them into poly(dimethyl siloxane) resin. PDMS is a polymer that will set into a very flexible, clear material when mixed with a cross-linking agent. We can make thin pieces with the microspheres mixed in and then sew the pieces into pockets in the gloves, similar to how we were planning to incorporate the lithium polymer battery. Professor Irvine has some PDMS that we can borrow. He is also going to order some polypropylene that we will use to test polyethylene glycol as an alternative phase change material.
• Bought fabric, patterns and string to make the gloves. We went with 4 different types of fleece for testing, and flannel to line the inside.
• Researched possible electrical insulators for our heating element. After calling a few companies we decided that teflon tubing may be a good option. The tubing would be flexible enough to bend with fingers and should have no problem with breaking. Ordered two different sizes of teflon tubing (26 and 28 gauge) from http://www.hamiltoncomp.com/product/oem/tubing.html and more wire.

Wed 3 April 02

• Jeff and Tiffany met with Prof. Powell this morning to discuss heat tranfer analysis. Click here to view our progress.
• Completed fabrication of octadecane microspheres. We used a different method to separate the microspheres from the PVA solution because so much material was lost last time with the centrifuging technique. This time the microspheres were put through an 0.22 micron filter. The microspheres gathered at the top of the filter while the PVA solution went through. The particles were also rinsed using the filter. The filter was then sonicated to remove as many particles as possible and the microspheres were frozen in liquid nitrogen, as before. Click here for complete procedure.

Tues 2 April 02

• Began fabricating the octadecane microspheres. The fabrication procedure was exactly the same as for the paraffin spheres except that the octadecane dissolved much more easily in the methylene chloride so there was no need to heat it up. Two sets of microspheres were fabricated: one at a homogenizer speed of 4.0 and one at 5.0.
• Erin Lavik helped us take SEM images of the paraffin microspheres to estimate their diameter. They actually looked more like platelets than spheres and there was not a very noticable difference between the microspheres fabricated at different homogenizer speeds. Click here to see the images.
• To see a notebook section on the progress of a steady-state heat transfer model for the gloves, click here.

Mon 1 April 02

• Kristin tested tensile strength of wires. Click here for results.

Mon 25 Mar 02

• Click here for the results of the DSC measurements performed on octadecane and PEG900.

Thurs 21 Mar 02

• Completed fabrication of paraffin microspheres. Click here for description.
• Colin measured temperature inside and outside of a glove heated by wire heating elements, powered by a power supply set at 3.6V. Maximum temperature measured inside the glove was ~112°F. Click here for the details and results of this experiment.

Tues 19 Mar 02

• Click here for the results of the wire resistance measurements performed on 03-19-02.
• Colin set up for measurement of heat output from the gloves using wire heating elements, which will be performed later this week.
• Filtered PVA solution for microsphere fabrication.
• Began fabrication of paraffin microspheres. Click here for description.

Mon 18 Mar 02

• Made the PVA solution necessary for fabricating paraffin microspheres (5% PVA solution in water). Click here for procedure.

Fri 15 Mar 02

• Ordered polyethylene glycol (PEG) and octadecane to begin testing phase change materials. These two materials have melting temperatures near the human body temperature, making them suitable for our application. Processing will involve microsphere fabrication, encapsulation, and finally incorporating the spheres into the glove.
• Click here for more information about the use of phase change materials, including safety information about PEG and octadecane.
• Order placed: Sigma-Aldrich, http://www.sigmaaldrich.com, Polyethylene glycol, Product #: 81187, $32.40, 1 Unit = 1kg.
• Order placed: Sigma-Aldrich, http://www.sigmaaldrich.com, Octadecane, Product #: 74710, $23.85, 1 Unit = 100g.
• Click here for the results of the DSC measurements performed on 03-15-02.
• Notes for using the Perkin Elmer Pyris 1 Differential Scanning Calorimeter (DSC), located in CMSE's Analysis Shared Experimental Facility
  • Make sure there is enough LN₂ in the dewar connected to the DSC. If LN₂ level is low, it must be filled.
  • If you are the first person using the DSC for that day, start by warming up the DSC: Open the DSC software à Click Open Method à choose the "warmuppyris" routine à click the start button on the RHS of the software screen.
  • You must collect a baseline for an empty pan if you wish to subtract the baseline from your measurement. Take two empty pans, of the type that you will be using (desired volume, holes or no holes), secure the lid of the pan, and load them into the DSC. On the computer, on the "Sample Info" tab, enter the sample ID name and comments (such as the type of pan used, eg. 50m L with holes). Enter the filename.
  **Our data is stored under D:\Program Files\Pyris\Data\Pyris 1 DSC\Glove
  On the Program tab, enter the Method Steps. For example:
  1) Hold for 3.0min at -20.00° C. (for stabilizing sample temperature after loading it)
  2) Heat from -20 to 200° C at 10° C/min
  When collecting a baseline, use the same method steps that you will use when measuring your sample.
  
  • To Prepare your Sample: Put an empty pan in the Mettler H51 (mass scale) and zero the scale. Then put your sample in the pan and secure the lid. Put your sample into the Mettler and measure its mass. (When you apply pressure to secure the lid onto your sample pan, a ring around the lid detaches. Do not forget to place this ring back into the Mettler when measuring mass.)

Tues 12 Mar 02

• Professor Ceder has found some lithium polymer batteries for us to use. They should arrive within a few days from Valence Technologies. We will receive two 1 amp*hour batteries and two 750 milliamp*hour batteries, with a peak current of 150 Amps. He told us to be very careful not to short the tabs on the battery. We will order some fuses to ensure that the current will not go above what is necessary for the gloves. He also told us never to wear the glove while charging the battery because lithium batteries can be dangerous when overcharged. He will help us to recharge the batteries when it becomes necessary.
• Some of our wire came in this afternoon. On Thursday we will begin testing their mechanical properties with Ms. Yin-Lin Xie. Because the samples are so thin, standard Instron testing will not work and we may have to use special procedures. One possibility is to mount the ends of the wire in clamps that the Instron can grip better. We are currently looking for any ASTM standard testing procedures that may help us with this.
• Obtained a sample of paraffin wax from Ms. Yin-Lin Xie. Reserved time with Tim McClure to use the DSC on Friday. We will test both the paraffin wax and a sample of material from an instant heat pack from CVS to measure how much heat they can give off.
• Began temperature testing so determine the temperature at which the glove heaters should switch off. This was done using a hair dryer to heat the gloves while someone was wearing them. The temperature at which they said the glove was hot inside was recorded. Values of 98 and 101 were obtained. We will continue with these tests tomorrow to get a wider range of data.
• Inquired about temperature switch availability from several companies. We will order the switches as soon as we have decided the temperature where the gloves will switch off.

Mon 11 Mar 02

• Order Placed: Newport Electronics, www.newportinc.com, 714-540-4914, Resistance Heating wire Ni:Cr:Fe 60:16:24wt%, 0.404mm diameter, Model #NI60-015-50, 50ft, $10. R = 2.670 ohms/ft at 20° C. detailed info about item: www.newportinc.com/Products/Wire/NI60.htm

• Order Placed: Alfa Aesar, Stainless Steel wire, 0.38mm diameter, annealed, Fe:Cr:Ni 70:19:11 wt%, Stock #43301, 100cm, $21.00.

Fri 8 Mar 02

• Order Placed: Alfa Aesar, www.alfa.com, 1-800-343-0660, Nickel Chromium wire (0.41mm diameter), Stock #42196, Ni:Cr 80:20wt%, 25 meters, $18.50. R = 2.571 ohms/ft at 20° C. Alfa Aasar Technical Services faxed to Tiffany a chart of resistance/ft for the different diameters of Nichrome wires and stainless steel wires.
• Contacted Lithium Power to inquire about obtaining a sample battery to work with.

Thurs 7 Mar 02

• Order Placed: Land's End, http://www.landsends.com, Women's Polartec Aircore-200 Gloves, Item #7433-9AH4, Color = Alpine Green, Size= Large, Price = $15.00, Quantity = 1.
• Order Placed: Land's End, http://www.landsends.com, Women's Windbloc Gloves, Item #6234-0AH2, Color = Black, Size = Large, Price = $30.00, Quantity = 1.

Wed 6 Mar 02

• Kristin and Bushra spoke with Prof. Rubner about the fabric thermal testing procedures. He recommended not trying to do thermal property tests on the materials themselves using any sort of hot plate and thermocouple or thermometer to test for thermal conductivity. He, as well as Prof. Roylance, who Jeff and Kristin went and spoke with, felt there were too many variables which needed to be taken into account. Both professors suggested going to the library and having the reference librarian help use the search engines to locate information on heat transmission of textiles. Prof. Roylance also suggested we contact Prof. Stanley Backer, who we called and left a message with.
• Jeff and Kristin went to both Hayden and Barker libraries to locate information about thermal properties of textiles (fabrics). There were a few thesis written, located in off-campus archives, of which we requested microfiche copies to see if they, perhaps, will have the thermal property values.
• We have located a company that supplies phase change materials. We will order both Thermasorb and parrafin wax to test over the next couple weeks, although at this stage it seems as though the battery will provide more heat in the gloves.
• Finalized the latest version of our design for tomorrow's presentation.

Tues 5 Mar 02

• Contacted Malden Mills and spoke with Jim Gillette in the marketing dept about the thermal properties of fabrics. Te said that fabric companies don't calculate any specific value of thermal conductivity, because it is too difficult to get a precise number due to the large number of variables. He also warned us against the wiring. He said that the wiring can't be too thick, or get too hot because if it's too warm or too thick it will melt the material. However, at 100-105 degrees, we should be fine.
• Contacted U.S. Sensors to get information about our temperature sensor. They referred us to RayChem and we have just received their catalog. The prime candidate for our temperature sensor is a switch made from carbon black embedded in a polymer.
• Continued research and materials selection for various areas of heated gloves. Began putting our different ideas together to reach our final design. These pages have been updated: Batteries, Fabrics, Heating Element, Phase Change Materials, Heat Sensor.
• Finished our rough calculation of the heat loss of the human hand. We estimated it to be approximately 3 Watts. Hopefully the addition of an insulating fabric will reduce this to approximately 1 Watt, the target power output of our glove.

Thurs 28 Feb 02

• Continued research on different aspects of the glove heaters (from Feb 26).
• Began research to come up with a power consumption estimate. We are trying to obtain a rough estimate of the thermal conductivities of the insulating fabrics that we are considering using from their manufacturers. This will allow us to complete the power consumption calculation and begin battery selection by Tuesday.
• Also researched potential ways to measure the effectiveness of the glove heaters and, as a first step, the properties of our insulating fabrics.

Tues 26 Feb 02

• Research that we have conducted over the past week:
  Batteries
  Fabrics
  Heating Element
  Phase Change Materials
  Heat Sensor
• Met with Professor Ceder about battery possibilities. He also helped us figure out a very rough estimate of the power consumption of our gloves based on the average heat loss of the human body. In the next few days we will try to come up with a more accurate estimate based on possible choices of insulating material. This will allow us to select candidate materials for the different elements of the gloves (battery, heating element, etc.).
• We may also need to research incorporating a thermal fuse into the glove as a safety check. Depending on how hot the gloves will get, insulation around the wires may not be enough.

Thurs 21 Feb 02

• Aspects of the Glove Heaters to research were distributed among the team members as shown below. Leads for finding information and questions are also listed.

• Websites of heated gloves already on the market:
  http://www.electrichandwarmers.com/glove.html
  http://www.gerbing.com/
  http://ecom1.sno-ski.com/product105.html

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