1.1 This International Standard 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 oC/h
— Method B50 using a force of 50 N and a heating rate of 50 oC/h
— Method A120 using a force of 10 N and a heating rate of 120 oC/h
— Method B120 using a force of 50 N and a heating rate of 120 oC/h.
1.2 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.