รายละเอียดเอกสาร

This test method covers determination of the coefficient of linear thermal expansion for plastic materials having coefficients of expansion greater than 1 µm/(m.°C) by use of a vitreous silica dilatometer. At the test temperatures and under the stresses imposed, the plastic materials shall have a negligible creep or elastic strain rate or both, insofar as these properties would significantly affect the accuracy of the measurements. Test Method E228 shall be used for temperatures other than −30°C to 30°C. This test method shall not be used for measurements on materials having a very low coefficient of expansion (less than 1 µm/(m.°C). For materials having very low coefficient of expansion, interferometer or capacitance techniques are recommended. Alternative technique commonly used for measuring this property is thermomechanical analysis as described in Test Method E831, which permits measurement of this property over a scanned temperature range.