The HDT and Vicat tests consist in determining temperature degree of a stressed sample that submits a deflection: in the HDT test sample submits a flexion, while in the Vicat test sample is penetrated by a tip.
The HDT (ISO 75) test involves samples under stress combined with initial force applied while immersed in a thermostatic-water bath whose temperature is increased at constant rate.
The temperature of deflection of a given value corresponds to the results of the analysis.
Sample is then immersed in a thermostatic-water bath at constant increased temperature rate. The result of the analyse is recorded when the needle penetrates samples.
