ASTM D7340-07(2023)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D7340 − 07 (Reapproved 2023)
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 D1610 Practice for Conditioning Leather and Leather Prod-
ucts for Testing
1.1 This practice is intended to determine the thermal
D1813 Test Method for Measuring Thickness of Leather
conductivity of a sheet material. This practice is not limited to
Test Specimens
leather, but may be used for any poorly conductive material
2.2 Other Standard:
such as rubber, textile and cork associated with the construc-
SATRA TM 146 Thermal Conductivity
tion of shoes.
1.2 A constant heat source is sandwiched between two 3. Terminology
identical metal cylinders which are mounted with their axes
3.1 Definitions:
vertical. A test specimen is placed on the top surface of the
3.2 thermal conductivity, n—the quantity of heat conducted
upper cylinder and a third identical metal cylinder is placed on
per unit time through unit area of a slab of unit thickness
top of the test specimen so that all the cylinders and the test
having unit temperature difference between its faces.
specimen are concentrically aligned (see Fig. 1). The heat
source is switched on and the temperatures of the three blocks
4. Summary of Practice
allowed to reach equilibrium. The thermal conductivity of the
4.1 A conditioned specimen of leather (see Practice D1610)
test specimen is then determined from the steady-state tem-
is placed between two plates at different temperatures. The
peratures of the three blocks, the exposed surface areas of the
upper plate is at a constant temperature while the temperature
blocks and test specimen and the thickness of the test speci-
of the lower plate is slowly changing. The temperature differ-
men.
ence is measured by thermocouples. The rate of flow of heat
1.3 This practice does not apply to wet blue.
through the specimen is proportional to the area and the
1.4 This standard does not purport to address all of the temperature difference of the faces of the specimen, and
inversely proportional to the thickness. Assuming no heat loss,
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- the amount of heat flowing through the specimen per unit time
priate safety, health, and environmental practices and deter- is equal to the amount of heat received by the lower plate
mine the applicability of regulatory limitations prior to use. (copper block receiver) per unit time.
1.5 This international standard was developed in accor-
5. Significance and Use
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the 5.1 Part of the function of a shoe is to assist the foot in
Development of International Standards, Guides and Recom- maintaining body temperature and to guard against large heat
mendations issued by the World Trade Organization Technical changes. The insulating property of a material used in shoe
Barriers to Trade (TBT) Committee. construction is dependent on porosity or the amount of air
spaces present. A good insulating material has a low thermal
2. Referenced Documents conductivity value, k. The thermal conductivity value increases
2 with an increase in moisture content since the k value for water
2.1 ASTM Standards:
is high, 0.0014 cal/s cm · °C (0.59 W/m·K).
6. Apparatus and Materials
This practice is under the jurisdiction of ASTM Committee D31 on Leather and
6.1 A “Lees’ disc” apparatus, see Fig. 1, consisting of:
is the direct responsibility of Subcommittee D31.03 on Footwear.
6.1.1 A metal, see 11.1.2, cylindrical block, which will
Current edition approved Dec. 1, 2023. Published January 2024. Originally
ɛ1
subsequently be referred to as block B1, with:
approved in 2007. Last previous edition approved in 2018 as D7340 – 07 (2018) .
DOI: 10.1520/D7340-23.
6.1.1.1 A diameter of (D), in millimetres, which is known to
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
an accuracy of 0.2 mm (see 11.1.1).
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
6.1.1.2 A height of (H), in millimetres, which is known to an
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. accuracy of 0.2 mm (see 11.2).
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D7340 − 07 (2023)
FIG. 1 SATRA Lees’ Disc Thermal Conductivity Apparatus
6.1.1.3 A small hole of diameter 2 mm 6 1 mm drilled 6.1.7 A device capable of measuring and displaying the
radially to its center. temperatures of the thermocouples in the four brass cylindrical
6.1.1.4 A type K thermocouple inserted into the hole until blocks to an accuracy of 60.2 °C.
its junction is at the bottom of the hole.
6.2 A circular press knife of diameter (D) 6 0.5 mm.
6.1.1.5 The remaining volume of the hole filled with a high
6.3 A dial thickness gauge which applies a pressure of
thermal conductivity compound with a thermal conductivity of
13.86 oz 6 0.35 oz (393 g 6 10 g) on the test specimen and is
better than 0.8 W/(m°C), for example a metal oxide filled paste
capable of measuring to an accuracy of 0.01 mm. This is
of the type used between high power semiconductor electronic
identical to the gauge used in Test Method D1813.
devices and heat sinks.
6.1.2 A circular electrical heater element which:
7. Preparation of Test Specimens
6.1.2.1 Has a diameter of (D) 6 0.5 mm.
7.1 Place the uncut sheet material in a standard controlled
6.1.2.2 Is capable of dissipating a minimum power density
environment of 20 6 2 °C ⁄65 6 2% relative humidity or 23 6
of 400 W/m from each of its circular faces. See 11.1.1.
2 °C ⁄50 6 2% relative humidity or for a minimum of 48 h.
6.1.2.3 Has a cylindrical metal block, see 11.1.3, with
Include details of the conditions used in the test report.
thermocouple as block B1 (6.1.1), of diameter (D) 6 0.5 mm
and of height (H) 6 0.2 mm bonded to its top and bottom faces
7.2 Use the press knife (6.2) to cut two circular test
with a high thermal conductivity adhesive compound. These
specimens of diameter (D) 6 0.5 mm.
two blocks will subsequently be referred to as B2 and B3.
(Warning—Do not attempt to separate these blocks from the
8. Procedure
heater element.)
8.1 Use the thickness gauge (6.3) to measure the thickness
6.1.3 A fourth metal cylindrical block fitted with a thermo-
(S) at the center of each test specimen and record these two
couple as (6.1.1) of diameter (D) 6 0.5 mm and of thickness
values in millimetres to the nearest 0.05 mm.
8 mm 6 2 mm. This is for measuring the ambient temperature
8.2 Ensure that the heater assembly (6.1.2) is mounted
of the surrounding atmosphere and will subsequently be
vertically so that block B2 is above block B3 (see Fig. 1). It
referred to as block B4.
should also be situated in a temperature-controlled environ-
6.1.4 A power supply unit connected to the heater element
ment of
...