Determination of physical properties of irradiated PTFE fibers using digital holographic microscopy

A method that depends on digital holographic microscopy (DHM) was suggested for studying the effect of gamma irradiation doses on the physical properties of polytetrafluoroethylene (PTFE) fibres. The PTFE samples were exposed to different doses of gamma irradiation ranging from 3 to 40 kGy. These samples were fast monitored using a DHM based on a Michelson interferometer. The holographic pattern generated across the recording domain of the DHM was used for extracting the optical path differences (OPD) within the samples under test. From the OPD, the optical and the physical variations of irradiated fibers were characterized by determining their refractive indices, birefringence, orientation function, 3D refractive index profile, and crystallinity. It was found that optical parameters were increased by increasing the doses of gamma irradiation until 10 kGy, while these values decrease at doses 25 kGy and 40 kGy. Also, the crystallinity results showed the improvement of its values by gamma irradiation results in the crosslinking of PTFE fibres by irradiation.