Uniaxial Creep Response of Double-Layered Pressure Sensitive Adhesive (PSA)

Creep response of double-layered PSA bonded assemblies were investigated in this study. Both single-layered and double layered PSA systems are widely used in industry as a bonding medium. Although creep response of single layered PSA is relatively well studied, the creep response of double layered PSA is not fully understood. Creep response of double-layered PSA differs from that of single layered creep PSA, in the presence of two noticeable transitions observed in the creep curve of highly ductile double layered PSAs, while only one transition is observed in the same PSA with single layered configuration. The inclusion of a carrier layer in the double layered configuration introduces an additional set of interfaces into the PSA system, thus allowing sequential cavitation and fibrillation in two adhesive layers. Such transitions can dramatically change the creep resistance and significantly influence the creep deformation. These mechanistic behaviors have not been captured in the conventional creep models available in literature [1-6]. In addition to empirical observation, a predictive mechanistic model is presented in this paper. This model can: (i) capture the characteristic features, such as primary and secondary transitions, in the creep response of double-layered PSA bonded assemblies; (ii) account for the effect of adhesive, carrier layer, and substrate material properties (such as surface roughness and surface free energy), on the creep performance of double-layered PSA bonded assemblies.