Birefringence (Double Refraction) Testing of Plastic and Polymeric Materials for high volume and high performance materials

Birefringence in polymer films measures polymer orientation, which is related to physical properties of the films. Intertek determines the birefringent properties of a wide range of optical materials materials for clients. Birefringence testing of plastics by Intertek is competitive, with prompt sample analysis turn-around times from receipt of samples.

The refractive index components are determined with an accuracy around +/- 0.0005, the lab is able to determine birefringence to about +/- 0.001. Birefringence analysis is normally conducted at a wavelength of 633nm, but other wavelengths can be used if necessary. The birefringence test method utilises reflectivity measurement, and determines the refractive indices at the sample surface. If the composition or orientation of the polymer varies throughout the thickness the laboratory will not pick this up, and the sample should have at least one flat surface on which measurements can be made.

What is Birefringence?

'Double Refraction' is another way to describe Birefringence. Double Refraction is the splitting of a light ray into two separate rays when the original light ray passes through certain materials, including polymers and plastics. Minimisation of birefringence is important in processing polymers for applications such as CD and DVD manufacturing.

Our scientists examine the nature of the high and low areas of a material's birefringence in order to aid development scientists and engineers improve process specifications, and to improve overall yield; the benefit of which will manifest in the areas of high volume and high performance plastics.

Contact Intertek