本文件规定了两种测定塑料折射率的试验方法，即: -？方法？A:通过折射计测量模制零件、铸造或挤压板材或薄膜折射率的折射计方法。它不仅适用于各向同性透明、半透明、有色或不透明材料，也适用于各向异性材料。 -？方法？B:通过显微镜测定粉末或粒状透明材料折射率的浸入法（利用贝克线现象）。通常，单色光用于避免色散效应。 注？折射率是一种基本属性，可用于检查纯度和成分、材料识别和光学部件设计。 折射率随温度的变化可以指示材料的过渡点。

This document specifies two test methods for determining the refractive index of plastics, namely: —？Method？A: a refractometric method for measuring the refractive index of moulded parts, cast or extruded sheet or film, by means of a refractometer. It is applicable not only to isotropic transparent, translucent, coloured or opaque materials but also to anisotropic materials. —？Method？B: an immersion method (making use of the Becke line phenomenon) for determining the refractive index of powdered or granulated transparent materials by means of a microscope. Monochromatic light, in general, is used to avoid dispersion effects. NOTE？The refractive index is a fundamental property which can be used for checking purity and composition, for the identification of materials and for the design of optical parts. The change in refractive index with temperature can give an indication of transition points of materials.