Characterizing Films of Polyethylene Blends: An Application of Colorimetric Parameters Measurements

This study reports an application of instrumental color measurement for quantifying and comparing the optical properties of high density polyethylene and low density polyethylene blend films and the effect of blending ratio on these properties. The optical properties of the films indicated the probability of affecting the color spectrum by incorporating low density polyethylene into high density polyethylene. This is the principal reason for changing colorimetric parameters of the films. It was indicated that the presence of more than 25% low density polyethylene in the blend films causes higher L*-indices comparing to other corresponding blend films. Besides, growing in b* value of some samples is a sign of a little color shift from white to yellow in the color space. Hue angle of the films containing up to 85% high density polyethylene declined with increasing high density polyethylene content in the blend films. Comparing CIE coordinates proved that hue angle values have significant magnitude, so the difference of blend films and the trend of color intensity variations become more obvious. Whiteness and yellowness indices showed the same trend as L* and b* and C*, respectively. In this paper, it is indicated that YI, WI, hue angle and CI are useful factors to compare the transparent films of polyethylene blends.