Examples of UL temperature indices

To give a general idea, UL temperature indices of thermoplastics are in a range of 50°C up to more than 200°C for exceptional families. 

Like all the laboratory methods, the temperature index is an arbitrary measurement that must be interpreted and must constitute only one of the elements by which judgement is made. 

The HDT is the temperature at which a standard deflection occurs for defined test samples subjected to a given bending load and a linear increase in temperature. The stresses usually selected are 0.46 MPa (HDT B) or 1.8 MPa (HDT A) and must be indicated with the results. In any case, the polymer cannot be used under this load at this temperature. 

Generally, HDTs are in a range of 20°C up to more than 400°C for exceptional families. For a given thermoplastic family, HDT is affected by reinforcement fillers and plasticizers. 

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