GB/Z 32013-2015New textile materials - Datasheet of thermal properties (English PDF)

1 Scope

This guiding technical document gives the basic thermal property data of certain textile fibres: the glass transition temperature, the melting point, the enthalpy of fusion, the thermal decomposition temperature and the thermal mass-loss ratio.

This guiding technical document applies to ultra-high molecular weight polyethylene fibre, aramid 1414, aramid 1313, polyphenylene sulfide fibre, polyimide fibre, polytrimethylene terephthalate fibre, polybutylene terephthalate fibre, polylactic acid fibre, chitosan fibre and lyocell fibre.

2 Terms and definitions

The following terms and definitions apply to this document.

2.1 glass transition temperature - the temperature at which an amorphous or semi-crystalline polymer changes from the rubbery (viscoelastic) state to the glassy state. [Source: GB/T 6425-2008, definition 3.5.4.1]

2.2 melting point - the temperature at which the crystalline regions inside the material change from the crystalline to the molten state.

2.3 enthalpy of fusion - the quantity of heat needed to melt the material at constant pressure, in kJ/kg or J/g. [Source: GB/T 19466.3-2004, definition 3.3]

2.4 thermal decomposition temperature - the temperature at which the macromolecules inside the material are broken down into small molecules.

2.5 thermal mass-loss ratio - the ratio of the mass lost when the material is heated to a particular temperature to its initial mass, expressed as a percentage.

2.6 differential scanning calorimetry - the technique of measuring, under programmed temperature control and in a definite atmosphere, the relation between the heat flow rate or heating power (difference) supplied to the specimen and the reference material and the temperature or time. [Source: GB/T 6425-2008, definition 3.2.9]

2.7 differential scanning calorimetry curve (DSC curve) - the graphical representation of the relation between the heat flow rate or heating power (difference) supplied to the specimen and the reference material, measured by a differential scanning calorimeter, and the temperature or time. The ordinate of the curve is the heat flow rate, also called the heat flow, in mW (mJ/s); the abscissa is the temperature or the time. [Source: GB/T 6425-2008, definition 3.2.10]

2.8 thermogravimetry (TG) - the technique of measuring, under programmed temperature control and in a definite atmosphere, the relation between the mass of the specimen and the temperature or time. [Source: GB/T 6425-2008, definition 3.2.1]

2.9 thermogravimetric curve (TG curve) - the curve expressing the data measured by thermogravimetry in the form of the change of mass (or mass fraction) with temperature or time. The ordinate of the curve is the mass m (or mass fraction), upwards indicating an increase and downwards a decrease in mass; the abscissa is the temperature T or the time t, from left to right indicating a rise in temperature or an increase in time. [Source: GB/T 6425-2008, definition 3.2.5]

3 Table of thermal property data

The table of the thermal property data of new textile material fibres is Table 1, which gives for each fibre the glass transition temperature in degrees Celsius, the melting point in degrees Celsius, the enthalpy of fusion in J/g, the thermal decomposition temperature in degrees Celsius, and the thermal mass-loss ratio in per cent at 400, 600 and 800 degrees Celsius.

Ultra-high molecular weight polyethylene fibre: glass transition not shown; melting point 146; enthalpy of fusion 238 to 258; decomposition 450 to 470; mass loss 2 to 5, 99, 100. Aramid 1414: decomposition 580 to 590; mass loss 0 to 2, 14 to 28, 50 to 64. Aramid 1313: decomposition 430 to 440; mass loss 0 to 2, 32 to 36, 46 to 52.

Polyphenylene sulfide fibre: glass transition 100; melting point 279; enthalpy of fusion 40 to 55; decomposition 505 to 510; mass loss 0 to 1, 55 to 65, 60 to 70. Polyimide fibre: decomposition 530 to 600; mass loss 0 to 3, 5 to 15, 40 to 73.

Polytrimethylene terephthalate fibre: glass transition 51; melting point 221; enthalpy of fusion 60 to 65; decomposition 375 to 390; mass loss 30 to 40, 97, 100. Polybutylene terephthalate fibre: glass transition 38; melting point 225; enthalpy of fusion 60 to 70; decomposition 380 to 390; mass loss 24 to 36, 95 to 98, 100.

Polylactic acid fibre: glass transition 58; melting point 150 to 165; enthalpy of fusion 35 to 55; decomposition 315 to 340; mass loss 98, 100, 100. Chitosan fibre: decomposition 270 to 295; mass loss 44 to 53, 53 to 62, 60 to 66. Lyocell fibre: decomposition 315 to 330; mass loss 77 to 80, 83 to 88, 91.

Note 1: a dash in the glass transition temperature column indicates that the glass transition temperature is not evident on the DSC curve. Note 2: the melting points of aramid 1414, aramid 1313 and polyimide fibre are high and close to the thermal decomposition temperature, or are not evident. Note 3: chitosan fibre and lyocell fibre have no melting point.

4 Test methods

4.1 The determination of the glass transition temperature, the melting point and the enthalpy of fusion is carried out according to Annex A.

4.2 The determination of the thermal decomposition temperature and the thermal mass-loss ratio is carried out according to Annex B.

Annex A (normative) Determination of the glass transition temperature, the melting point and the enthalpy of fusion

A.1 Principle. Using a differential scanning calorimeter with an inert gas as the carrier, the DSC curve of the specimen is measured under rising temperature; the melting peak temperature Tpm is taken as the melting point and the area between the melting peak and the line closing it as the enthalpy of fusion (see Figure A.1). On the DSC curve measured under rising temperature after the thermal history of the specimen has been removed, the midpoint temperature Tmg is taken as the glass transition temperature of the specimen (see Figure A.2).

In Figure A.1, Teim is the extrapolated onset temperature, the temperature corresponding to the intersection of the baseline with the tangent at the point of maximum slope of the curve where the transition begins; Tefm is the extrapolated end temperature, the temperature corresponding to the intersection of the baseline with the tangent at the point of maximum slope of the curve where the transition ends; and Tpm is the peak temperature, the temperature corresponding to the maximum (or minimum) value of the peak.

In Figure A.2, Teig is the extrapolated onset temperature, the intersection of the initial baseline extrapolated from the low-temperature side of the curve with the tangent at the inflection point of the curve; Tefg is the extrapolated end temperature, the intersection of the initial baseline extrapolated from the high-temperature side of the curve with the tangent at the inflection point of the curve; and Tmg is the midpoint temperature, the intersection of the curve with the line equidistant from the two extrapolated baselines.

A.2 Equipment and materials. A.2.1 Differential scanning calorimeter, whose main performance is as follows: a) able to raise or lower the temperature at a constant rate of 0.5 degrees C/min to 20 degrees C/min; b) able to hold the test temperature constant within plus or minus 0.5 degrees C for at least 60 min; c) gas flow rate in the range 10 mL/min to 50 mL/min, with the deviation controlled within plus or minus 10 %; d) the instrument can record the DSC curve automatically and can integrate the area, with a deviation of less than 2 %.