JIS K7142-2008《塑料–曲折率的求取方法》

This Standard specifies two test methods for determining the refractive index of plas-
tics, namely:
-- Method A: a refractemetric method for measuring the refractive index of moulded
parts, cast or extruded sheet or film, by means ofa refractometer. It is applicable
not only to isotropic transparent, translucent, coloured or opaque materials but also
to anisotropic materials. The method is recommended when great accuracy is re-
quired. It is not applicable to powdered or granulated material.
-- 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 should, in general, be used to avoid
dispersion effects. The accuracy of this method is about the same as that of
method A. It is applicable to isotropic translucent, coloured materials but is not
applicable to opaque materials nor to anisotropic materials