Bending Fatigue Analysis of Various Polymer Films by Real-Time Monitoring of the Radius of Curvature and Heat Generation

Abstract

Understanding the fatigue behavior of polymer films under cyclic bending is essential to the design of suitable substrates for flexible electronics. However, bending fatigue remains unclear due to the lack of comprehensive and quantitative investigations across various polymer films. Herein, we quantitatively investigate the bending fatigue behavior of various polymer films with a newly developed multifunctional bending fatigue tester that can precisely evaluate the radius of curvature and heat generation during the fatigue process. Measuring the radius of curvature reveals that the polymer structures affect the surface bending strain and fracture modes, which are critical factors in fatigue life. Furthermore, heat is accumulated in polymer films under high-rate cyclic bending, leading to thermal degradation and a shortening of the fatigue life. These investigations provide us with an effective variable for machine learning and improve the prediction accuracy of the fatigue life. The resultant perspectives enable us to comprehend the fatigue behavior and fatigue life of polymer films subjected to cyclic bending, facilitating the development of flexible electronic devices and soft robots.