ASTM D542-14  Refraction of Transparent Organic Plastics Test 

Scope:

This test method measures a key feature of matter that is important for the design of optical parts as well as the control of purity and composition for straightforward identification. The readability of this test method extends to four figures to the right of the decimal point.

Test Procedure: 

In the ASTM D542-14 test method, the hinged illumination prism is taken out of the refractometer. A diffuse polychromatic light source is placed such that the plane of the surface of contact between the specimen and the refractometer prism is evenly illuminated. A little drop of the appropriate contacting liquid is placed on the specimen’s polished surface before it is placed in firm contact with the prism’s surface, with the polished side facing the designated light source. The same method described for liquids is used to determine the index of refraction. The refractometer’s index arm is adjusted until the field visible through the eyepiece is half-dark. The compensator (Amici prisms) drum is adjusted to eliminate color.

The average value for a thin layer of a small area at a point of contact close to the refractometer prism’s center is known as served. Measurements are taken at multiple locations both on the material’s surface and within its body to fully and accurately determine how the index varies across the test specimen. A contacting surface that is parallel and perpendicular to the molding pressure or flow is prepared for this purpose. After the test object makes contact with the prism, it is gently moved a few inches along the prism surface in the direction of the light source while the refractometer measures the index variation.

Test Specimen:

The ASTM D542-14 test specimen needs to be a size that will easily fit on the face of the refractometer prisms’ fixed half. Typically, a specimen that measures 6.3 by 12.7 mm on one face is acceptable.

Data:Conditioning: 

Standard test procedure using Conditioning ASTM D542—In line with Procedure A of Practice D 618, condition the test specimens at 23  ± 2°C and 50 ± 5% relative humidity for at least 40 hours before the test. The limits should be 61°C and 62% relative humidity in cases of dispute.

Test Conditioning:

Conduct tests at 23 ±2°C and 50 ±10 % relative humidity, unless otherwise directed in a pertinent specification. In cases of disagreement, the tolerances shall be 61°C and 65 % relative humidity. If the index of refraction of the material is found to be highly temperature dependent, then the temperature shall be accurately controlled to 23 ±0.2°C

Read more: ASTM D6050 Determination of Insoluble Solids in Organic Liquid

Conclusion:

As per the given data ASTM D542-14 Standard Test Method, We can determine the index of refraction of Transparent Organic Plastics.