Industrial and commercial tubing may be comprised of layers, dependent upon the final tubing application. In this application, the different layers provide discreet properties dictated by the environment to which each of the layers will be exposed. The FT-IR microscopic technique may be used to characterize the individual layers of the tubing.

Example:

Multilayer tubing used for fuel applications was prepared for light microscopy and infrared microscopy by cutting 10 and 15-micron thick sections on a microtome using a diamond knife. The sections were imaged in a compound light microscope fitted with a digital camera. Layer thickness was determined by use of a micrometer photographed using the same settings as the tubing layers.

The tubing sections were placed under the infrared objective of a Thermo-Nicolet NicPlan® IR microscope. The image was centered and an aperture mask used so that only the layer of interest was visible. In this way, a transmission spectrum was obtained of each layer of each piece of tubing.