Thermodilatometry of Laminated Glass

In this report, we describe the application of standard thermodilatometry (TD) as a tool to evaluate the thermal behavior of laminated glass assemblies where two glass layers are bonded together by a polymer interlayer. The measurement of the displacement perpendicular to the plane of the glass multilayer enables to follow the thermal expansion up to the point where interfacial debonding, thermal degradation, or another thermal event takes place. The effect of heating rate has been investigated and a procedure is eventually proposed to estimate the onset temperature at interfacial failure from the TD data. It is also shown that TD measurements of the interlayer along the side of the glass laminate give a sharp signal at interfacial failure. Finally, following the sandwich seal model where it is assumed that, during heating, the constrained interlayer is in compression due to the mismatch in thermal expansivity between the outer glass and the inner polymer layer, we establish the stress–strain behavior of the interlayer up to the debonding temperature. Viscoelastic and structural relaxation of the interlayer are taken into account empirically from modulus and thermal expansion data collected along similar thermal paths.