What is haze？
Haze is also called turbidity. It indicates the degree of unclearness of transparent or translucent materials. It is the appearance of cloudiness or turbidity caused by light scattering inside or on the surface of the material. It is expressed as the percentage of the ratio of the scattered light flux to the light flux through the material.
Why measure haze？
Haze measurement can be used to quantify the optical properties of plastics and packaging films. Obscure films in packaging applications can reduce consumer perception of quality, such as when packaging products look blurry. For plastics with haze, the visibility of the test material becomes more pronounced and reduces the contrast of the observed objects.
Factors affecting haze measurement
Part1:
light source
Different light sources have different relative spectral energy distributions. Because various transparent plastics have their own spectral selectivity, the same material is measured with different light sources, and the obtained light transmittance and haze value are different. The darker the color, the greater the impact.In order to eliminate the influence of the light source, the International Institute of Illumination (CIE) has specified three standard light sources A, B, and C. This method uses a "C" light source.
Part2:
Influence of surface condition
The surface state of the sample mainly refers to whether the surface is flat and smooth, whether there are scratches and defects, and whether it is contaminated.
Part3:
Effect of specimen thickness
As the thickness of the sample increases, the light absorption increases, the light transmittance decreases, and light scattering increases, so the haze increases. Transmission and haze can only be compared at the same thickness.