scope:

Under conditions of industrial applications, the thermal expansion of a plastic is composed of a reversible component on which are superimposed changes in length due to changes in moisture content, curing (degree of polymerization), loss of plasticizer or solvents, release of stresses, and other factors. This method of test is intended for determining the reversible linear thermal expansion under exclusion of these accidental factors. In general, it will not be possible to exclude all these accidental factors and for this reason the method can be expected to give only approximate values. The dilatometer described in the Appendix to this method has the advantage of simplicity, but it is not intended to be used when results of great accuracy are desired; it is also not applicable to very soft plastics such as elastomers.