Vicat Softening Temperature (VST) according to ISO 306

With the VST we measure at which temperature an indenter has penetrated the plastic sample to a depth of 1 mm. The plastic sample is placed in the holder and is subject to a pre-defined weight and lowered down inside the oil bath. The oil is heated at a defined rate and when the identer has penetrated the sample with a depth of 1 mm we have reached the VST.

 

ISO 306 prescribes 4 different test methods:

Method A 50: test weight of 10 N and heating rate of 50 K/h.

Method A 120: test weight of 10 N and heating rate of 120 K/h.

Method B 50: test weight of 50 N and heating rate of 50 K/h.

Method B 120: test weight of 50 N and heating rate of 120 K/h.

 

Heat Deflection Temperature (HDT) according to ISO 75

The heat deflection temperature (HDT) to ISO 75 indicates the relative behavior of different types of material under load at elevated temperatures. It is determined on materials such as thermoplastics, hard rubber or duroplastic laminates

 

Test Procedure

To test according to ISO 75, a sample has to be subjected to flexural stress before loading it into the oil bath; therefore the sample is placed in a 3-point flexure test holder and is  loaded with a defined   test weight as per Standard. The temperature is then increased at a uniform heating rate of 120K/h. The HDT is defined as the temperature at which the specimen reaches the deflection as specified in the Standard.

ISO standards define an increase in flexural strain of 0.2% whereas ASTM defines an absolute deflation of 0.25 mm.

The standard also specifies how the specimen is to be positioned on the anvil: flatwise or edgewise. Flexural stress: The standards also specify different flexural stresses.

 

ISO 75 

Method HDT A: flexural stress = 1.8 MPa

Method HDT B: flexural stress = 0.45 MPa

Method HDT C: flexural stress = 8.0 MPa

 

ASTM D 648

1.82 MPa and 0.455 MPa

Duropl. laminates:1/1000 of flexural Young’s modulus

 

 

The BAYERTEQ HDT / VICAT model A

our A model boosts 3, 4, 5 or 6 stations and each station is equipped with an individual temperature measuring points

 

Technical Specifications:

• Number of test stations: 3, 4, 5 or 6
• automatic weight loading
• Lifting of the test stations: automatic
• Control: touchscreen or Pc control
• Room temp – 300 °C
• Heating rate: 120°C/H or 50°C/H
• Heating rate accuracy: max 1% / 6 min
• Temperature accuracy: max 0,5 °C
• Number of temperature measuring points: for each station an individual measuring point
• Thermal expansion coefficient of test stations: 0,005 mm / 100 °C
• Deformation measuring device: digital gauge with interface
• Span of sample supports: 64 mm, 100mm
• Max deformation measuring error: 0,005 mm
• Medium: methyl silicon oil
• Cooling: natural cooling
• Equipped with temperature protective circuit
• Software included
• Power supply: 220 V, 50 Hz

 

our model ‘A’ comes with the following features:

• controlled by PC or touch screen, equipped with software to control test temperature and deformation, describe & record test curves, output testing result, save historical data as well as print out testing results, etc.
• automatic loading and off loading can be finished during the lifting procedure.
• thanks to new material application and unique structure, the expansion coefficient of specimen frame has been controlled at the minimum value.
• dispersion of testing results for standard specimen is smaller than 0.5_, even under the smallest load.
• automatic smoke exhaust system has been designed to guarantee the operator’s heath and not contaminate the environment,
• application of digital micrometer with communication interface ensures top class performance in mechanic & electronic controlling ability,
• temperature protective circuit, being independent from the controlling system, is designed to protect the tester when temperature of medium exceeds its using range,