Optical Properties of Polymers

Polymer optical properties testing covering haze, gloss, colour, clarity and more, bringing you the insight to accelerate, develop and optimise

Optical properties of polymers, such as, gloss, transparency, clarity, haze, colour, surface aspect and refractive index, are closely linked to our perception of a plastic product’s quality and visual performance. Polymer optical properties testing will bring you insight to accelerate development and to optimise or troubleshoot production.

Optical properties are dependent on the specific polymer or copolymer material, the formulation (colourants, fillers, plasticizers and other additives) and the crystallinity of the materials. But also mechanical and chemical degradation or aging processes and the mechanical conditions and / or temperature treatments applied during processing influence the optical properties of polymers and polymer formulations. Any negative impact to a polymer’s optical properties - such as aging - can affect the product’s lifetime, even whilst the functional or mechanical properties still meet specifications.

The aesthetics of a product must be maintained throughout product’s packaging, transport and storage, or in the automotive industry where a consumer’s perception of ‘glossy’, strong, surface features are inextricably linked to the 'value' of the product.

From our independent perspective, we expertly analyse a range of optical properties, delivering accurate information which helps to achieve the desired aesthetics during development, production or in the end-use application.

During production, various steps such as colouration, heat treatment and mechanical processing can affect optical properties. Through our testing programs - including fundamental tests such as Gloss, Haze, Birefringence and Ultra-Violet and Visable (UV/VIS) light absorption and transmission - Intertek can help you to optimise production in order to achieve optical property specifications.

Our polymer scientists understand that the optical properties of polymers are closely related to the chemical microstructure, thermal and physical properties of these materials, and as such, providing comprehensive expertise which spans chemical, thermal plus physical and mechanical testing. Our industry application experts take you beyond the test result, applying their experience and knowledge to gain improvement of a material's optical properties.

Intertek's scientists understand that the optical properties of polymers are closely related to the chemical microstructure, thermal and physical properties of these materials, and as such, we provide comprehensive expertise that covers chemical, physical, mechanical and thermal testing. Our industry application experts take you beyond the test result, using their experience and knowledge to provide the guidance you need to achieve improvement of a material's optical properties.

Polymer and plastic testing:

Most polymers are typically grey or yellow coloured. White fillers or other optically active additives colour additives can help to make the appearance more suited to application. Our experts use colour measurement via LAB colour space and XYZ colour space to evaluate color change due to exposure to adverse conditions or to help match parts molded from different materials or assess color changes due to surface texture or molding or processing.

Yellowness Index is a number calculated from spectrophotometric data that describes the change in color of a test sample from clear or white to yellow. Intertek uses the yellowness index test to evaluate color changes in a material caused by real or simulated outdoor exposure.

Gloss is the capacity of the polymer surface to reflect light in a given direction. Intertek provides testing for gloss on a range of sample types and sizes, at different incidence angles delivering comparative data between similar samples thus supporting development and end use performance testing.

Haze is an optical effect caused by light scattering within a transparent polymer resulting in a cloudy or milky appearance. Our polymer scientists use spectrophotometer techniques to investigate a range of issues which result in haze as a symptom such as weathering, during product and process development.

The refractive index and light transmission of transparent materials for example, those use in lenses, optical fibres, large screen displays or coatings, are relatively straightforward to measure accurately. Intertek’s polymer laboratories use refractive index as a diagnostic tool to help understand the critical stress in a system or the resulting impact of additives or heat treatments (such as cross linking, or annealing) have on the material. We also provide ultra-violet and visible (UV/VIS) light absorption and transmission measurements.

The refractive index varies with orientation of the polymer chains on a molecular level; our polymer scientists use polarized light to achieve birefringence effects which can be used to quantify the stress in a transparent plastic.