ASTM D7340-07(2018)

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of the standard as published by ASTM is to be considered the official document.
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Designation: D7340 − 07 (Reapproved 2012) D7340 − 07 (Reapproved 2018)
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.
ε NOTE—The k value in 5.1 was corrected editorially in April 2012.
1. 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.
1.4 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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.5 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.
2. Referenced Documents
2.1 ASTM Standards:
D1610 Practice for Conditioning Leather and Leather Products for Testing
D1813 Test Method for Measuring Thickness of Leather Test Specimens
2.2 Other Standard:
SATRA TM 146 Thermal Conductivity
3. Terminology
3.1 Definitions:
3.2 thermal conductivity—the quantity of heat conducted per unit time through unit area of a slab of unit thickness having unit
temperature difference between its faces.
4. Summary of Practice
4.1 A conditioned specimen of leather (see Practice D1610) is placed between two plates at different temperatures. The upper
plate is at a constant temperature while the temperature of the lower plate is slowly changing. The temperature difference is
measured by thermocouples. The rate of flow of heat through the specimen is proportional to the area and the temperature
difference of the faces of the specimen, and inversely proportional to the thickness. Assuming no heat loss, the amount of heat
flowing through the specimen per unit time is equal to the amount of heat received by the lower plate (copper block receiver) per
unit time.
This practice is under the jurisdiction of ASTM Committee D31 on Leather and is the direct responsibility of Subcommittee D31.03 on Footwear.
Current edition approved April 1, 2012Nov. 1, 2018. Published April 2012November 2018. Originally approved in 2007. Last previous edition approved in 20072012 as
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D7340D7340-07(2012) -07. DOI: 10.1520/D7340-07R12E01.
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D7340 − 07 (2018)
FIG. 1 SATRA Lees’ Disc Thermal Conductivity Apparatus
5. Significance and Use
5.1 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, 0.0014 cal/s cm · °C (0.59 W/m·K).
6. Apparatus and Materials
6.1 A “Lees’ disc” apparatus, see Fig. 1, consisting of:
6.1.1 A metal, see 11.1.2, cylindrical block, which will subsequently be referred to as block B1, with:
6.1.1.1 A diameter of (D), in millimetres, which is known to an accuracy of 0.2 mm (see 11.1.1).
6.1.1.2 A height of (H), in millimetres, which is known to an accuracy of 0.2 mm (see 11.2).
6.1.1.3 A small hole of diameter 2 6 1 mm drilled radially to its center.
6.1.1.4 A type K thermocouple inserted into the hole until its junction is at the bottom of the hole.
6.1.1.5 The remaining volume of the hole filled with a high thermal conductivity compound with a thermal conductivity of
better than 0.8 W/(m°C), for example a metal oxide filled paste of the type used between high power semiconductor electronic
devices and heat sinks.
6.1.2 A circular electrical heater element which:
6.1.2.1 Has a diameter of (D) 6 0.5 mm.
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.
6.1.2.3 Has a cylindrical metal block, see 11.1.3, with 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 with a high thermal conductivity adhesive compound. These two blocks
will subsequently be referred to as B2 and B3. (Warning—Do not attempt to separate these blocks from the heater element.)
6.1.3 A fourth metal cylindrical block fitted with a thermocouple as (6.1.1) of diameter (D) 6 0.5 mm and of thickness 8 6
2 mm. This is for measuring the ambient temperature of the surrounding atmosphere and will subsequently be referred to as block
B4.
6.1.4 A power supply unit connected to the heater element (6.1.2). The unit should be capable of supplying sufficient power to
enable the heater element (6.1.2) to dissipate a power density of 400 W/m from each of its circular faces.
6.1.5 A means of measuring the power being supplied to the heater element (6.1.3) to an accuracy of 64 mW. See 11.1.2.
6.1.6 A method of mounting the heater and block assembly (6.1.2) so that air can circulate freely around all the outside edges
of the assembly.
D7340 − 07 (2018)
6.1.7 A device capable of measuring and displaying the temperatures of the thermocouples in the four brass cylindrical blocks
to an accuracy of 60.2°C.
6.2 A circular press knife of diameter (D) 6 0.5 mm.
6.3 A dial thickness gauge which applies a pressure of 13.86 6 0.35 oz (393 6 10 g) on the test specimen and is capable of
measuring to an accuracy of 0.01 mm. This is identical to the gauge used in Test Method D1813.
7. Preparation of Test Specimens
7.1 Place the uncut sheet material in a standard controlled environment of 20 6 2°C/65 6 2%
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