GLove: Heated Gloves*
Kristin Brodie, Jeff Colton, Colin Galbraith, Bushra Makiya and Tiffany Santos
Summary: The goal of this project was to create a heating system for a pair of gloves that maintain a comfortable temperature and wearability. The main
components of the glove are the heating element, battery, insulation, thermal switch and fabric. The heating elements extensively studied were highresistance metallic wires and phase change materials. The glove design below displays the aspects of materials selection when utilizing either form of
heating. This design supplies 1.7W of power to each hand. The resistive heating element selected was Ni:Cr high resistance wire and the phase change
material selected was octadecane embedded in polydimethyl siloxane resin.
Amount of heat supplied to the hand by the heating element was determined by calculating the amount of heat needed
to keep the hand comfortable when walking across the Harvard Bridge in -10°C weather with 15 mi/hr wind.
Ni:Cr High Resistance Wire
• 80% Ni, 20% Cr
• Diameter = 0.40mm
• Resistance = 0.0807 /cm
• 100 cm of wire used in design
• Wire temperature reaches 60C
• Selected for superior mechanical properties compared to
other wires (largest elastic region, see graph below).
• Other high-resistance wires considered: 60Ni:16Cr:24Fe
Lithium Polymer Battery
and 70Fe:19Cr:11Ni.
• Flat shape - dimensions: 65 x 36 x 6 mm
• Located at the back of the hand.
• Voltage supplied: 3.74V
• Rechargeable
• 4.4 Watt*hours
• Compliments of Valence Technologies.
Outer Fabric
• 100% polyester fleece selected for its good
insulating properties, breathability, and high heat
transfer coefficient.
• Melting Temperature = 260C
• Heat transfer coefficient = 1.49 W/m2*K
• Good breathability: hand will sweat minimally
inside glove.
• Other fabrics considered: 80/20 and 20/80
cotton/polyester blends.
Required Power
(W)
Required Power vs Temperature
20C 80P
2
100P
1.5
1
240
20P 80C
100P*
260
280
300
Temperature (K)
Inner Lining Fabric
• 100% polyester
• Selected for softness and comfort.
• Other fabrics considered: flannel (100% cotton).
Teflon Tubing Insulation
Phase Change Materials (PCMs)
A PCM is melted by body heat and the latent heat of fusion is stored.
When subjected to a cooler environment, the PCM crystallizes,
releasing the stored heat and thus warming the hand.
• Poly(tetrafluoroethylene): -(CF2-CF2)• High Melting Temperature = 327C
• Thermal Conductivity = 0.25W/m*K
• Necessary for electrical insulation of wires and protection
from corrosion.
Bi-Metallic Thermal Switch
It is necessary to encapsulate the PCM into a base material such as
polypropylene or high density polyethylene in order to prevent leakage
when the PCM melts. Because extrusion facilities were not available,
uniformly dispersing a PCM in either one of these materials proved to
be very difficult. Therefore less efficient encapsulants had to be used.
PCMs considered: Octadecane in Polydimethyl Siloxane (PDMS)
Resin and Polyethylene Glycol (PEG) in Polyethylene.
• Octadecane C18H38
• Molecular Weight = 254.5g/mole
• Melting Temperature = 27.2˚C
• Crystallization temperature = 16.5˚C
• (Measured by Differential Scanning Calorimetry)
• Total Heat Capacity: 5g  283.5J/g = 1148J
• Embedded in PDMS Resin:
• Thermal Conductivity = 0.002 W/m*K
•
Integrated into the electric circuit is a bimetallic strip, containing
two metals of different thermal expansion coefficients layered
together. As the temperature rises, one of the metals elongates
more than the other, forcing the strip to bend away from the
contact and opening the circuit. Cooling releases the tension in
the strip, and the circuit is closed.
• Switch Temperature = 32C1
• Switches off heating circuit when switch temperature is
reached, preventing overheating.
• Compliments of Portage Electric Products, Inc.
• Other thermal switches considered: polymer thermal
switch, thermistor.
Final PCM Glove Comparison
Final Gloves (left to right): Inner lining with
battery and resistive heating element, inner
lining with embedded PCMs, and outer glove.
Comparison of PCM and Wire
Heating Elements:
5 grams of octadecane will give off
the same amount of heat upon
freezing per cycle (~1.7 W) as 100cm
of Ni:Cr wire in ~14 minutes.
• Polyethylene Glycol (PEG)
• Molecular Weight = 190-210g/mole
• Melting Temperature = 26.6˚C
• Crystallization temperature = 9.8˚C
• (Measured by Differential Scanning Calorimetry)
• Total Heat Capacity: 7g  150.8J/g = 1056J
• Heat sealed into a polyethylene bag.
• Thermal Conductivity = 0.33 W/m*K
• -(CH2-CH2)•The PCM embedded in base material was then sewn into pockets in
the inner lining of the glove according to the pattern below.
*3.082 Materials Processing Laboratory, Undergraduate Team Project
Octadecane in PDMS
PEG in Polyethylene
A comparison of the two encapsulation methods is shown above.
Although polyethylene proved to be a better encapsulant due to
the low thermal conductivity of PDMS (%reduction in efficiency =
35% vs. 51%), the overall heat capacity of the octadecane
embedded in PDMS resin was greater (93.1J/g vs. 61.2J/g). This
was due to the larger weight fraction of PCM in that sample and
its higher latent heat storage capacity. Therefore octadecane was
used in the gloves. In the future, it would be interesting to
experiment with heat sealing octadecane in polyethylene. This
could further increase the glove’s efficiency.