ISO 11357-8:2021 Plastics — Differential scanning calorimetry (DSC) —Part 8: Determination of thermal conductivity

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Plastics — Differential scanning calorimetry (DSC) —Part 8: Determination of thermal conductivity是ISO于2021-02发布的ISO标准，适用于世界范围。

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Plastics — Differential scanning calorimetry (DSC) —

Part 8: Determination of thermal conductivity

1 Scope

This document establishes a method for determination of the thermal conductivity of solid unfilled and filled or fibre reinforced plastics and composites by means of differential scanning calorimetry (DSC).

It is applicable for materials with thermal conductivities of up to 1 W/(m⋅K).

2 Normative references

The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

ISO 291, Plastics — Standard atmospheres for conditioning and testing

ISO 472, Plastics — Vocabulary

ISO 6344-1, Coated abrasives — Grain size analysis — Part 1: Grain size distribution test

ISO 11357-1, Plastics — Differential scanning calorimetry (DSC) — Part 1: General principles

3 Terms a nd definiti ons

For the purposes of this document, the terms and definitions given in ISO 472 and ISO 11357-1 apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/o bp

— IEC Electropedia: available at http://w ww.e lectropedia. org/ 4 Principle

For the determination of thermal conductivity, the usual placement of the specimen in the sample holder position is modified according to a procedure proposed in References [1] and [2] Additional details on scientific background, deduction of results and performance of measurements can be found in References [3] and [4].

An empty crucible is placed in the reference position of the sample holder assembly. The test specimen is placed directly onto the sensor of the sample position and a crucible containing a substance of known melting temperature is put on top of the specimen (see Figure 1). The thermal conductivity is measured at a temperature slightly above the melting point of this substance in the small temperature range in which the slope of the melting peak with test specimen is determined (see 9.4, Figure 2).

Upon heating, a temperature gradient is created in the specimen. The temperature of the top of the specimen remains constant at the melting temperature T of the melting substance while the m

temperature of the bottom side of the specimen corresponds to the temperature of the sample side

sensor. The differential heat flow between sample and reference sensor is measured by the DSC instrument.

From the temperature difference between top and bottom of the sample (T - T ), the sample height h m p



and the heat flow rate difference Q between sample and the reference sensor, the thermal conductivity of the specimen is determined.

Key

h height of specimen

 heat flow rate difference between sample and reference position

Q

S sensor of sample position

p

S sensor of reference position

r

T melting temperature of the known substance and the temperature of the top of the specimen

m

T temperature of the sample position and the bottom side of the specimen

p

T temperature of the reference position

r

Figure 1 — Schematic layout of measurement

5 Apparatus and substances

5.1 DSC instrument

A DSC instrument in accordance with specifications given in ISO 11357-1 shall be used.

Only original raw data shall be used without any further data processing.

NOTE According to currently available results, the method has been verified with heat-flux type DSC instruments only. However, it is expected that power-compensated DSC instruments are also suitable.

5.2 Crucibles

Aluminium crucibles shall be used fitting the DSC instrument. Both, open or ventilated closed crucibles are suitable. Upon using sealed crucibles suitable precautions shall be taken to prevent excessive inside pressure.

Care shall be taken to avoid deformation of the plane crucible bottom.

NOTE Uneven crucible bottoms can result in too low thermal conductivity values.

5.3 Melting substance

Certified melting substances or melting substances having a purity of 99,999 9 % or better shall be used.

The melting temperature determines the temperature of measurement of the thermal conductivity.

Melting temperatures of specimens to be measured shall be above those of the melting substances to be used. In case of doubt, this shall be ensured by performing suitable preliminary tests.

NOTE Metals such as gallium or indium have been found suitable.

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