This document specifies two methods for evaluating the melting behaviour of semi-crystalline polymers.
Melting temperatures determined by the different methods usually differ by several kelvins for the reasons explained in the introduction.
Method A: Capillary tube
This method is based on the changes in shape of the polymer. It is applicable to all semi-crystalline polymers and their compounds.
NOTE 1 Method A can also be useful for the evaluation of the softening of non-crystalline solids.
Method B: Polarizing microscope
This method is based on changes in the optical properties of the polymer. It is applicable to polymers containing a birefringent crystalline phase. It may not be suitable for plastics compounds containing pigments and/or other additives which could interfere with the birefringence of the polymeric
NOTE 2 Another method applicable to semi-crystalline polymers is described in ISO 11357-3, Plastics — Differential scanning calorimetry (DSC) — Part 3: Determination of temperature and enthalpy of melting and crystallization.