Study on Oil Resistance of Polyurethane Protective Material

Abstract The polyurethane protective tape is a new type of protective material made by coating high performance pressure-sensitive adhesive on polyurethane elastomers, which is widely used in aviation. During its operational life, the polyurethane protective tape inevitably comes into contact with oil, and its oil resistance directly impacts its lifespan. This study focuses on the polyurethane protective tape and conducts immersion tests in No. 15 aviation hydraulic fluid, aircraft gear oil 4450 and RP3 aviation kerosene at room temperature. A comparative analysis was also conducted on the tensile strength, tear resistance, fracture morphology, chemical structure, and thermophysical properties before and after immersion. The research indicates that the tensile properties of polyurethane protective tapes remain essentially unchanged after immersion in RP3 aviation kerosene. After being immersed in No.15 aviation hydraulic fluid and aircraft gear oil 4450, the tensile strength of the polyurethane protective tape gradually decreases. Furthermore, compared to No.15 aviation hydraulic fluid, the rate of tensile strength reduction in polyurethane protective tape immersed in aircraft gear oil 4450 is more rapid. The resistance to tearing of polyurethane protective tapes diminishes gradually with prolonged immersion, with the rate of decline being greater for aircraft gear oil 4450 than for No.15 aviation hydraulic fluid, and even greater for RP3 aviation kerosene. The decrease in mechanical properties of polyurethane protective tapes after immersion in oil is attributed to the swelling effect of the oil, which reduces the intermolecular forces within the polyurethane material and leads to a decrease in physical cross-linking. This process is physical aging, with no evident chemical aging occurring.