Statistical strength of a self-bonded incompatible polymer–polymer interface

Abstract

The thick bulk films of amorphous polystyrene (PS) and poly(ethylene terephthalate) (PET) were held in contact for various periods of healing time (t) of 5 min to 15 h at 3 constant healing temperatures T = 74 °C, 89 °C, and 108 °C ranging from below to above the bulk glass transition temperatures of the 2 polymers involved. As a result, the PS–PET single lap-shear adhesive joints which can bear the mechanical load were formed. As-formed PS–PET adhesive joints (or self-bonded asymmetric incompatible PS–PET interfaces) were shear-fractured in tension, and their lap-shear strength (σ) developed due to physical self-healing of the interfaces was measured as a function of T and t. The distributions of the measured σ values (totally, 16 data sets) have been analyzed in the framework of the Weibull statistical model, and the Weibull parameters (Weibull modulus and scale factor) were estimated and compared with those reported recently for other partially self-healed interfaces of amorphous and semi-crystalline polymers. The Weibull behavior of the polymer–polymer interfaces differing in the chain chemical structure, compatibility, crystallizability, and crystallinity has been discussed.