ISO 306

VICAT SOFTENING POINT

Specifies four methods for the determination of the Vicat softening temperature (VST) of thermoplastic materials:

  1. Method A50 using a force of 10 N and a heating rate of 50 °C/h
  2. Method B50 using a force of 50 N and a heating rate of 50 °C/h
  3. Method A120 using a force of 10 N and a heating rate of 120 °C/h
  4. Method B120 using a force of 50 N and a heating rate of 120 °C/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.
Source: www.iso.org