In recent decades, global warming has been pushing the design temperatures that engineers need to consider for various materials used in building construction. Laminated safety glass made with the most common interlayer material, Polyvinyl Butyral (PVB), is highly compliant with temperature and load durations. On the other hand, Ionoplast interlayers, originally developed for the hurricane market in the US after the catastrophic Hurricane Andrew in 1992, have now gained worldwide acceptance. This acceptance is attributed to the fact that Ionoplast interlayers have shear modulus values 100 times higher than those of PVB, even at elevated temperatures like 50°C.
In recent years, stiff PVBs have been introduced as a new class of structural interlayers, offering modulus values between standard PVB and Ionoplast for most time-temperature scenarios.
This paper presents experimental data on an improved stiff PVB version designed to address the limitations of existing stiff PVB products. The improved stiff PVB exhibits up to twice the shear modulus of current stiff PVB interlayers, resulting in significantly better post-glass breakage behaviour and enhanced design flexibility by applying the coupling approach. Additionally, the improved interlayer formulation provides superior long-term open edge stability, as evidenced, for example, by the results of the salt spray test (5000 hours, according to ASTM B117-11), and a more neutral colour while maintaining sufficient impact performance. These advancements open new design possibilities for façade engineers, making stiff PVB an attractive alternative to Ionoplast interlayers in temperature-controlled environments.