Analysis of environmental damage consequences on viscous thermo elastic properties of a polymer interlayer

Structural response of laminated glass elements is heavily influenced by the visco-thermo-elastic properties of polymer interlayer. Mechanical characterization of such polymers can be carried out with different experimental procedures such as creep tests, relaxation tests (both named transient tests) or tests with load or displacement periodically imposed. In the linear viscoelastic domain, mechanical parameters determined with such methods, are usually extended to time and frequency domain wider than the experimental one, translating the experimental points in the space of time or temperature, according to the time-temperature superposition principle. An incautious use of this procedure does not account for structural modifications that the polymer can suffer due to environmental actions such as solar radiation, temperature variations and moisture absorption. Here we describe the first results of an experimental campaign carried out with periodic tests on laminated glass specimens some of which previously exposed to moisture accelerated aging.