Effect of Temperature and Humidity on Mechanical Properties and Constitutive Modeling of Pressure- Sensitive Adhesives

Pressure-sensitive adhesives (PSAs) are crucial for the structural and functional integrity of flexible devices. This study conducts systematic mechanical tests, including uniaxial tensile, compression, planar shear, and stress relaxation, on PSAs at temperatures ranging from − 25℃ to 85℃ and relative humidity levels from 0–90%. The Ogden model effectively describes the hyperelastic behavior of PSAs under large deformations, as indicated by an R-Square value above 0.97. The results show that temperature markedly affects PSA properties, particularly near the glass transition temperature (Tg), with lower temperatures leading to decreased elasticity and higher temperatures aiding in stress relaxation. Similarly, humidity impacts PSA behavior, increasing elasticity and decreasing stiffness, especially noticeable in stress relaxation tests. These findings highlight the substantial influence of environmental conditions on the material properties of PSAs and underscore the necessity of understanding both hyperelastic and viscoelastic responses for their application in flexible technologies. This research provides critical insights for the optimal utilization of PSAs in the rapidly evolving field of flexible electronics, including OLED displays.