GB/T 40271-2021Test method for identification of textile fibers—Differential scanning calorimetry (DSC) (English PDF)

3.1 Melting

Melting refers to the transition from a solid state of a completely crystalline or partially crystalline substance to a liquid state with different viscosities. [source: GB/T 6425-2008, 3.5.5.1]

3.2 Enthalpy of Fusion

Enthalpy of fusion refers to the quantity of heat required for material melting under a constant pressure.

NOTE: it is expressed in kJ/kg or J/g. [source: GB/T 19466.3-2004, 3.3, modified]

3.3 Differential Scanning Calorimetry

Differential scanning calorimetry refers to a technique of determining the relationship between the heat flow rate or heating power (difference) delivered to the specimen and the reference substance, and temperature or time under program control temperature and certain atmosphere. [source: GB/T 6425-2008, 3.2.9]

3.4 Differential Scanning Calorimetry Curve (DSC curve)

Differential scanning calorimetry curve (DSC curve) refers to a graphical representation of the relationship curve between the heat flow rate or heating power (difference) delivered to the specimen and the reference substance measured by the differential scanning calorimeter, and temperature or time.

NOTE: the y-coordinate of the curve is heat flow rate, which is also known as heat flow and expressed in mW (mJ·s-1); the x-coordinate is temperature or time. [source: GB/T 6425-2008, 3.2.10, modified]

3.5 Calibration

Calibration refers to a set of operations of determining the relationship between the indicated value of the measuring instrument or measuring system and the already-known value corresponding to the measured value under specified conditions.

3.6 Instrument Baseline

Instrument baseline refers to a thermal analysis curve measured with empty sample cuvettes of the same mass and material, and without the use of specimen. [source: GB/T 6425-2008, 3.5.3.1 a), modified]

8.1 Melting Peak Temperature

The test curve of the melting peak temperature is shown in Figure 1. From the Figure, respectively read the melting peak temperature (Tpm) of each specimen; the result shall be accurate to 0.1 °C. Take the average value of all specimens as the melting peak temperature of the sample; the result shall be rounded off to an integer. If the second temperature-raising is performed, take the value measured after the second temperature-raising as the test result. The melting peak temperature of synthetic fibers is shown in Appendix C.

8.2 Enthalpy of Fusion

The test curve of the enthalpy of fusion is shown in Figure 1. Take the area between […]

A.1 General Rules of Calibration

The differential scanning calorimeter is a sensitive thermal analysis instrument, which requires regular temperature and heat calibration. Under the circumstances of changing test temperature range, changing air source and flow rate, changing refrigeration system or being idle for a long time, before use, at least two standard samples shall be used for the calibration of temperature and heat. See Appendix B for commonly used standard samples.

NOTE: other calibration requirements of the instrument may comply with the recommendations by the manufacturer, or with the assistance of the manufacturer in the implementation.

A.2 Temperature Calibration

A.2.1 Select at least two standard samples with the same mass as the specimen to be tested and whose extrapolated initial temperature is at or close to the temperature range to be tested.

A.2.2 Under the same test conditions as the specimen to be tested, determine the extrapolated initial temperature of the standard samples and record it.

A.2.3 By comparing the standard value and the recorded value of the standard samples, determine the temperature correction coefficient for calibration. Alternatively, the computer system may automatically compare and calibrate in accordance with the standard value and the recorded value.

A.3 Heat Calibration

A.3.1 Select at least two standard samples with the same mass as the specimen to be tested and whose extrapolated initial temperature is at or close to the temperature range to be tested.

A.3.2 Under the same test conditions as the specimen to be tested, determine the enthalpy of fusion of the standard samples and record it.

A.3.3 By comparing the standard value and the recorded value of the standard samples, determine the heat correction coefficient for calibration. Alternatively, the computer system may automatically compare and calibrate in accordance with the standard value and the recorded value. […]