The FIR refractive index of polymers determined by the ABBE technique.

The FIR refractive index can be determined quite accurately using laser radiation and Abbe's prism technique. Experimental data for polyethylene and TPX are presented. The refractive indices turn out to be a good means for determining the density of the polymers. The refractive index of polyethylene is determined in the temperature 4.2-300 K. (IPM)