Determination of Haze and Luminous Transmittance of Transparent Plastics using ASTM D1003, Method B. Haze is the property of partial clarity in plastics; clearer is the plastic, lower is its haze value, better is its surface appearance.
When light scatters upon passing through a film or plastic-like material, it can produce an unclear or smoky effect. So, objects look hazy when viewed through the material. The factors responsible for this scattering of light are the impurities present in the plastic material, surface abrasion, and weathering of the material. This property of partial clarity in plastics is called Haze. Lower the haze measurement value, the higher the clarity of the material, indicating fewer impurities. As it can affect surface appearance quality, haze is an important property of plastic materials to consider in widely used applications like food packaging.
All plastic materials come with some degree of light scattering, which is usually measured by ASTM D1003. A highly automated BYK Gardner Spectrophotometer measures the degree of transmission loss. Illuminant, observer angle and the reference color are specified before the test sample is placed into the specimen holder. The spectrophotometer then takes the reading. After taking three readings, the average of the results is calculated. Haze value is measured as the percentage of incoming light scattered by more than 2.5° through the plastic material. It has no specific unit and is expressed in percentage.
Customarily, a 50 mm (2 inches) or 100 mm (4 inches) disk or any flat sample that the specimen holder can hold is used as a specimen.ASTM D882 uses 1-inch 6 inches strips are die cut from thin sheets or film.
Haze, Total Luminous Transmittance, Diffuse Transmittance are all measured in percentages (%).