Laminated Glass For All Applications
Laminated Safety GlassLaminated glass manufactured thru Sinclair Glass is a type of glass that remains intact when shattered. In the event of breaking, it is held in place by an interlayer, typically of Polyvinyl Butyral (PVB), between its two or more layers of glass. Laminated glass is considered to be “safety glass” in the sense that the broken pieces of glass are still bonded to the transparent plastic interlayer(s) in case of glass breakage. The interlayer keeps the layers of glass bonded even when broken, and its high strength prevents the glass from breaking up into large sharp pieces. This produces a “spider web” cracking pattern when the impact is not enough to completely pierce the glass.
Laminated glass is normally used when there is a possibility of human impact or where the glass could fall if shattered. Skylight glazing and automobile windshields typically use laminated glass. In geographical areas requiring hurricane-resistant construction, laminated glass is often used in exterior storefronts, curtain walls and windows. The PVB interlayer also gives the glass a much higher sound insulation rating, due to the damping effect, and also blocks 99% of incoming UV radiation.
One of the potential transparent plastic interlayer, is probably one of the best-known currently, is SGP (SentryGlas® Plus, a stiffer “structural” interlayer by DuPont de Nemours). The lamination process is very similar for SGP and PVB. The most significant practical difference is that SGP films are delivered in plates, while the PVB films are delivered in rolls. This material is known to be stiffer than usual PVB. Sinclair Glass will always identify the best materials for each project, based on current technology.
Post-Breakage Behavior of Laminated Safety Glass
The post-breakage stadium of laminated glass is defined as the state when one or more glass sheets are cracked and the broken glass pieces are still bonded to the interlayer. Actually, the breakage of the glass plies can be caused by various effects: local impact (from a hard object), overall impact (explosion, etc.), thermal shock, static load, etc. In any case, the evaluation of the post-breakage behavior is of importance for safety aspects, to avoid consequences of collapse of the cracked element, before it has been replaced.
All experimental test breakage methods are mainly focusing on the performances of laminated glass used as glazing, mounted vertically in a closed frame along its edges, and for rather dynamic breakage conditions. However, most test methods appear insufficient to extrapolate the post-breakage behavior – in rather static conditions – for other configurations, e.g. for non-vertical elements, for other clamping of fixing boundaries, etc. as it is used in particular for structural applications. In that case, the post-breakage behavior has nowadays generally to be evaluated experimentally, due to the lack of predictive models.