1.1 This International Standard specifies two methods of test for determining the refractive index of transparent plastics, namely
Method A: Refractometric method for measuring the refractive index of transparent cast, moulded or sheet materials by means of a refractometer. The method is recommended when great accuracy is required. It is not ap-plicable to powdered or granulated transparent materials.
Method B: Immersion method (Becke line phenomenon) for determining the refractive index of powdered or granulated transparent materials by means of a microscope and making use of the Becke line phenomenon. Monochromatic light should, in general, be used to avoid dispersion effects. The accuracy of this method is about the same as that of method A.
1.2 Refractive index is a fundamental property which can be used for the control of purity and composition, for the iden-tification of materials and for the design of optical parts.
The change of refractive index with temperature may give an indication of transition points of materials.
SIS SS-ISO 489:1987 history
1987SIS SS-ISO 489:1987 Plastics - Determination of the refrac- tive index of transparent plastics