ISO 306:2013 specifies four methods for the determination of the Vicat softening temperature (VST) of thermoplastic materials:
— method A50 using a force of 10 N and a heating rate of 50 K/h;
— method B50 using a force of 50 N and a heating rate of 50 K/h;
— method A120 using a force of 10 N and a heating rate of 120 K/h;
— method B120 using a force of 50 N and a heating rate of 120 K/h.
The methods specified are applicable only to thermoplastics, for which they give a measure of the temperature at which the thermoplastics start to soften rapidly.
