Performance Comparison of Structural Interlayers

Abstract

Engineers and designers are using glass in increasingly demanding applications such as stairs, floors, and bridges, large minimally supported facades and overhead glazing.  The use of laminated glass in structural applications has become more recognized and preferred as safer choice to monolithic tempered or heat strengthen glass. Structural interlayers are stiff interlayers that increase the strength of the laminated glass enabling the glass structure to handle higher loads with thinner glass.  The use of structural interlayers enables laminated glass use in the most demanding applications giving architects and engineers greater design freedom. Today engineers and designers have options when choosing a structural interlayer for their application, Stiff PVB or ionoplast interlayer.  Both interlayers provide improved post breakage strength and structural benefits; however, some significant differences in properties that affect the final laminate performance exist.  Applications that require higher temperatures above 30⁰C and/or long load duration, ionoplast interlayers perform the best.   When the load duration or design temperatures are lower stiff PVB is a good choice.  From the laminators perspective properties such as yield and final laminate quality are important considerations as well.   There are differences between the structural interlayers seen during the lamination process that can influence lamination quality and yields.  Stiff PVB process similar to standard PVB while standard ionoplast interlayers require some special processing.   This may present a challenge for the laminators.  Recent improvements in ionoplast interlayer technology now enable ionoplast to be laminated more similar to PVB giving laminators and engineers the best of both.