ASTM D7340-07
(Practice)Standard Practice for Thermal Conductivity of Leather
Standard Practice for Thermal Conductivity of Leather
SIGNIFICANCE AND USE
Part of the function of a shoe is to assist the foot in maintaining body temperature and to guard against large heat changes. The insulating property of a material used in shoe construction is dependent on porosity or the amount of air spaces present. A good insulating material has a low thermal conductivity value, k. The thermal conductivity value increases with an increase in moisture content since the k value for water is high, 14 by 104 cal · cm/s · cm4 · °C (0.59 W/m·K).
SCOPE
1.1 This practice is intended to determine the thermal conductivity of a sheet material. This practice is not limited to leather, but may be used for any poorly conductive material such as rubber, textile and cork associated with the construction of shoes.
1.2 A constant heat source is sandwiched between two identical metal cylinders which are mounted with their axes vertical. A test specimen is placed on the top surface of the upper cylinder and a third identical metal cylinder is placed on top of the test specimen so that all the cylinders and the test specimen are concentrically aligned (see Fig 1). The heat source is switched on and the temperatures of the three blocks allowed to reach equilibrium. The thermal conductivity of the test specimen is then determined from the steady-state temperatures of the three blocks, the exposed surface areas of the blocks and test specimen and the thickness of the test specimen.
1.3 This practice does not apply to wet blue.
This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation:D7340–07
Standard Practice for
Thermal Conductivity of Leather
This standard is issued under the fixed designation D7340; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3. Terminology
1.1 This practice is intended to determine the thermal 3.1 Definitions:
conductivity of a sheet material. This practice is not limited to 3.2 thermal conductivity—the quantity of heat conducted
leather, but may be used for any poorly conductive material per unit time through unit area of a slab of unit thickness
such as rubber, textile and cork associated with the construc- having unit temperature difference between its faces.
tion of shoes.
4. Summary of Practice
1.2 A constant heat source is sandwiched between two
identical metal cylinders which are mounted with their axes 4.1 Aconditioned specimen of leather (see Practice D1610)
is placed between two plates at different temperatures. The
vertical. A test specimen is placed on the top surface of the
upper cylinder and a third identical metal cylinder is placed on upper plate is at a constant temperature while the temperature
of the lower plate is slowly changing. The temperature differ-
top of the test specimen so that all the cylinders and the test
specimen are concentrically aligned (see Fig. 1). The heat ence is measured by thermocouples. The rate of flow of heat
through the specimen is proportional to the area and the
source is switched on and the temperatures of the three blocks
allowed to reach equilibrium. The thermal conductivity of the temperature difference of the faces of the specimen, and
inversely proportional to the thickness.Assuming no heat loss,
test specimen is then determined from the steady-state tem-
peratures of the three blocks, the exposed surface areas of the the amount of heat flowing through the specimen per unit time
is equal to the amount of heat received by the lower plate
blocks and test specimen and the thickness of the test speci-
men. (copper block receiver) per unit time.
1.3 This practice does not apply to wet blue.
5. Significance and Use
1.4 This standard does not purport to address all of the
5.1 Part of the function of a shoe is to assist the foot in
safety concerns, if any, associated with its use. It is the
maintaining body temperature and to guard against large heat
responsibility of the user of this standard to establish appro-
changes. The insulating property of a material used in shoe
priate safety and health practices and determine the applica-
construction is dependent on porosity or the amount of air
bility of regulatory limitations prior to use.
spaces present. A good insulating material has a low thermal
2. Referenced Documents
conductivity value, k.The thermal conductivity value increases
with an increase in moisture content since the k value for water
2.1 ASTM Standards:
4 4
D1610 Practice for Conditioning Leather and Leather Prod- is high, 14 by 10 cal · cm/s · cm · °C (0.59 W/m·K).
ucts for Testing
6. Apparatus and Materials
D1813 Test Method for Measuring Thickness of Leather
6.1 A “Lees’ disc” apparatus, see Fig. 1, consisting of:
Test Specimens
6.1.1 A metal, see 11.1.2, cylindrical block, which will
2.2 Other Standard:
subsequently be referred to as block B1, with:
SATRA TM 146 Thermal Conductivity
6.1.1.1 Adiameter of (D), in millimetres, which is known to
an accuracy of 0.2 mm (see 11.1.1).
This practice is under the jurisdiction ofASTM Committee D31 on Leather and
6.1.1.2 Aheightof(H),inmillimetres,whichisknowntoan
is the direct responsibility of Subcommittee D31.03 on Footwear.
accuracy of 0.2 mm (see 11.2).
Current edition approved May 1, 2007. Published June 2007. DOI: 10.1520/
D7340-07. 6.1.1.3 A small hole of diameter 2 6 1 mm drilled radially
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
to its center.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
6.1.1.4 A type K thermocouple inserted into the hole until
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. its junction is at the bottom of the hole.
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D7340–07
FIG. 1 SATRA Lees’ Disc Thermal Conductivity Apparatus
6.1.1.5 The remaining volume of the hole filled with a high 6.1.7 A device capable of measuring and displaying the
thermal conductivity compound with a thermal conductivity of temperatures of the thermocouples in the four brass cylindrical
better than 0.8W/(m°C), for example a metal oxide filled paste blocks to an accuracy of 60.2°C.
of the type used between high power semiconductor electronic 6.2 A circular press knife of diameter (D) 6 0.5 mm.
devices and heat sinks. 6.3 Adialthicknessgaugewhichappliesapressureof13.86
6 0.35 oz (393 6 10 g) on the test specimen and is capable of
6.1.2 A circular electrical heater element which:
measuring to an accuracy of 0.01 mm. This is identical to the
6.1.2.1 Has a diameter of (D) 6 0.5 mm.
gauge used in Test Method D1813.
6.1.2.2 Is capable of dissipating a minimum power density
of 400 W/m from each of its circular faces. See 11.1.1.
7. Preparation of Test Specimens
6.1.2.3 Has a cylindrical metal block, see 11.1.3, with
7.1 Place the uncut sheet material in a standard controlled
thermocouple as block B1 (6.1.1), of diameter (D) 6 0.5 mm
environment of 20 6 2°C/65 6 2% relative humidity or 23 6
and of height (H) 6 0.2 mm bonded to its top and bottom faces
2°C/50 6 2% relative humidity or for a minimum of 48 h.
with a high thermal conductivity adhesive compound. These
Include details of the conditions used in the test report.
two blocks will subsequently be referred to as B2 and B3.
7.2 Use the press knife (6.2) to cut two circular test
(Warning—Do not attempt to separate these blocks from the
specimens of diameter (D) 6 0.5 mm.
heater element.)
6.1.3 A fourth metal cylindrical block fitted with a thermo-
8. Procedure
couple as (6.1.1) of diameter (D) 6 0.5 mm and of thickness 8
8.1 Use the thickness gauge (6.3) to measure the thickness
6 2 mm. This is for measuring the ambient temperature of the
(S) at the center of each test specimen and record these two
surroundingatmosphereandwillsubsequentlybereferredtoas
values in millimetres to the nearest 0.05 mm.
block B4.
8.2 Ensure that the heater assembly (6.1.2) is mounted
6.1.4 A power supply unit connected to the heater element
vertically so that block B2 is above block B3 (see Fig. 1). It
(6.1.2). The unit should be capable of supplying sufficient
should also be situated in a temperature-controlled environ-
power to enable the heater element (6.1.2) to dissipate a power
ment of 20 6 2°C and mounte
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