Comparative study of the insulation paper aging in palm fatty acid ester (PFAE) and mineral oil

For this study, we conducted accelerating experiments to investigate the aging of paper in PFAE and mineral oil. After the aging test, we evaluated paper tensile strength, water content of oils, and acid value of oils. As a result of the paper aging test, Kraft paper was found to degrade slower in PFAE than in mineral oil in a nitrogen atmosphere. Besides, we examined the relationships between the water contents of PFAE and paper. This examination revealed that water migrated readily from paper to PFAE. In addition, we measured the infrared spectroscopy of PFAE having various water contents. Consequently, it is suggested that water molecules are trapped by the ester group. These results indicate that water migrates readily from paper to PFAE.