Thermal Aging of Asahi SB-1000 Polymer Optical Fibers: Study on the Light Transmission Loss

Different samples of Asahi model SB-1000 polymer optical fibers arranged at different curvatures were aged to predict the loss of light transmission over 10 years. They were used in the FV0 detector of the ALICE experiment at the LHC. The fibers were exposed to 80°C, maintaining a relative humidity of less than 50% RH. The relative transmission loss was measured before and after aging. A maximum loss of 15% was found for 632 hr of aging, equivalent to 5 years for the ALICE experiment conditions considering thermal aging. This estimate is based on the Arrhenius model, using energy activation data from the literature. Complementary tests were done to analyze the fiber materials, such as XRD (WAX), FTIR, and mechanical tensile tests. For FTIR, no changes are found that indicate modifications in the chemical structure but in the physical properties of the materials. A study based on XRD shows that during the first 72 hr, changes in crystal size were observed, and consequently, there was a loss of transparency. Hence, mechanical tests indicate that the fiber decreases its Young’s modulus with longer aging times, making the material more tenacious to rupture.