Month: February 2022

HDT stands for Heat Deflection Temperature. The heat deflection temperature of a reinforced or unreinforced polymer material is a measure of polymer’s resistance to distortion under an applied load at elevated temperatures.

Applications of HDT tests include:

1) Identify suitable material for injection molding application.
2) Identify suitable material for elevated temperature application.
3) Identification and grading of materials as per their properties.

The test specification for the HDT is ASTM D 648 and ISO 75.

Factors Influencing Thermal Performance of Polymer Materials

HDT tests typically test for the short term performance of the materials under loads at elevated temperatures. The following factors play a significant part in the performance prediction of the materials under the test conditions.

1) The total time material is exposed to elevated temperatures.
2) The rate of temperature increase.
3) The specimen dimensions and part geometry.

Vicat softening temperature tests are used to identify the temperature at which a needle of specified dimensions penetrates into a plastic material specimen for a specified distance under applied loading conditions. The test specification for the Vicat softening temperature testing is ASTM D1525 and ISO 306.

Compared with the Heat Deflection Temperature (HDT), Vicat softening temperature test measures the temperature at which the specimen loses its stiffness and softens. HDT test measures the temperature at which the specimen loses its load bearing capability. The Vicat softening point is closer to the actual melting or softening point of the polymer. Vicat softening temperature is typically always higher than the HDT for a polymeric material as the penetration load is always higher than a bending load on a material specimen.

AdvanSES offers biaxial tension testing of rubber, elastomers and polymeric thin films. Biaxial testing is important for hyperelastic and viscoelastic characterization of elastomers and polymers for Finite Element Analysis FEA Applications. 

We carry out tests under the following biaxial tension deformation modes;

1) Single Stretch.

2) Multiple Cyclic Loading.

3) Single Stretch followed by Stress Relaxation Step.

Hyperelastic and Viscoelastic material characterization testing is carried out under the following deformation modes;

1. Uniaxial Tension Testing
2. Planar Shear Testing
3. Volumetric Compression Testing
4. Uniaxial Compression Testing
5. Biaxial Tension Testing

AdvanSES offers a choice of different capacities of load cells for biaxial testing high and low hardness materials, non-contact measurements and capacity to mold material test samples. 

Biaxial Tension Testing of Rubber is a key property for input into FEA softwares like Abaqus, Ansys, MSC Marc, LS-Dyna. Biaxial tensile testing is a non-traditional but highly accurate testing technique for mechanical characterization of soft and hard materials. Typical materials tested in biaxial tension are silicone and natural rubber elastomers, composites, polymeric thin films, and biological soft tissues.