Standard Test Method for Coefficient of Linear Thermal Expansion of Plastics Between −30°C and +30°C with a Vitreous Silica Dilatometer

Importancia y uso:

5.1 The coefficient of linear thermal expansion, α, between temperatures T₁ and T₂ for a specimen whose length is L₀ at the reference temperature, is given by the following equation:

Where L₁ and L₂ are the specimen lengths at temperatures T₁ and T₂, respectively. Therefore, α is obtained by dividing the linear expansion per unit length by the change in temperature.

5.2 The nature of most plastics and the construction of the dilatometer make −30°C to +30°C (−22°F to +86°F) a convenient temperature range for linear thermal expansion measurements of plastics. This range covers the temperatures in which plastics are most commonly used. When testing outside of this temperature range or when linear thermal expansion characteristics of a particular plastic are not known through this temperature range, particular attention shall be paid to the factors mentioned in 1.2.

Note 2: In such cases, special preliminary investigations by thermo-mechanical analysis, such as that prescribed in Practice D4065 for the location of transition temperatures, may be required to avoid excessive error. Other ways of locating phase changes or transition temperatures using the dilatometer itself may be employed to cover the range of temperatures in question by using smaller steps than 30°C (86°F) or by observing the rate of expansion during a steady rise in temperature of the specimen. Once such a transition point has been located, a separate coefficient of expansion for a temperature range below and above the transition point should be determined. For specification and comparison purposes, the range from −30°C to +30°C (−22°F to +86°F) should be used, provided it is known that no transition exists in this range.

5.3 Before proceeding with this test method, if appropriate, make reference to the specification associated with the material or product being tested. Any test specimen preparation, conditioning, dimensions, or testing parameters, or combination thereof, covered in the relevant ASTM material or product specification shall take precedence over those mentioned in this test method. If there are no relevant ASTM specifications, then the default conditions apply.

Subcomité:

D20.30

Referida por:

D0710-19, C1355_C1355M-96R20, D3105-17R24, D3748-14R19, F1499-22, D7793-24, D7745-19, F0964-13R24, D6434-12R18, D4477-24, D3679-24, F2021-17R22, F1551-23, D7445-24, D6455-11R18, F1488-14R19, E0289-17, D4216-22, F0942-18R23E01, E0831-24, D4101-24, F3319-20, E0228-22, D3841-21, F2855-19R24, F3562-24, F0790-23, D3678-19, F3459-21, D0229-19E01, D4762-23

Volúmen:

08.01

Número ICS:

83.080.01 (Plastics in general)

Palabras clave:

coefficient of expansion; linear expansion; plastics; thermal expansion;