Vicat Softening Point (VSP)

Vicat Softening Point (VSP)

1. This test gives a measure of the temperature at which a plastic starts to soften

rapidly.

2. A round, flat-ended needle of 1 mm2 cross section penetrates, the surface of a plastic test specimen under a predefined load, and the temperature is raised at a uniform rate.

3. The Vicat softening temperature, or VST, is the temperature at which the penetration reaches 1 mm.

4. Useful in quality control, development and to characterise the material. Also useful in comparing heat softening qualities of thermoplastics.

5. Test Method: ASTM D 1525, ISO-306, JIS-K7206, BS-2782 M.

Test Specimens:

• The specimen shall be flat, between 3 and 6.5mm thick and at least 10 by 10mm in area or 10mm in diameter.

Conditioning:

• 23 2oC and at 50 5% relative humidity of not less than 40 hrs

Limiting Oxygen Index

Oxygen index is defined as the minimum concentration of oxygen in a mixture of oxygen and nitrogen that will just support combustion.

Test method: ASTM D 2863, ISO 4589

specimen size: 150 x 6 x 4mm

The specimen is ignited and the concentration of oxygen is adjusted to burn for 3 minutes or 50 mm length.

                                                    100 x o2

percentage oxygen index = ---------------------

                                                      o2 + n2

Significance: the results allows to rate the material on numerical basis and simplifies the selection in terms of flammability.

• The purpose of the oxygen index test is to measure the relative flammability of materials by burning them in a controlled environment.

• The oxygen index represents the minimum level of oxygen in the atmosphere which

• Can sustain flame on a thermoplastic material.

• The test atmosphere is an externally controlled mixture of nitrogen and oxygen.