Vicat softening temperature (VST)
The Vicat softening temperature reflects the point of softening
to be expected when a material is used in an elevated temperature
application. The Vicat softening temperature was tested according
to ASTM D1525 Standard. A test specimen was placed in the testing
apparatus so that the penetrating needle rested on its surface at
least 1 mm from the edge. A load of 10 N was applied on the specimen.
The specimen was then lowered into an oil bath at room
temperature. The bath temperature was raised at a rate of
120 C/h until the needle penetrated into the specimen by 1 mm.