GB/T 39691-2020 Plastics—Determination of refractive index

Scope: This standard specifies two test methods for determining the refractive index of plastics: Method A: Refractometer method. Measure the refractive index of molded parts, die-cast or extruded sheets or films using the refractometer refractometry. Works with isotropic, transparent, translucent, colored or opaque materials, also works with anisotropic materials. This method is recommended when high-precision testing is required. This method is not applicable to powdery or granular samples. Method B: microscope immersion method (using the Baker line phenomenon). This method can be used to determine the refractive index of powdery or granular transparent materials. In general, monochromatic light should be used to avoid dispersion effects. This method is applicable to isotropic translucent materials and colored materials, but not to opaque materials and anisotropic materials.

GB/T 2918-2018 Standard environment for conditioning and testing of plastic specimens

GB/T 39691-2020Plastics—Determination of refractive index