PVB/SGP interlayer shear modulus If two sheets of glass, lying on top of one another, are placed under load, they will start to bend (distort) independently. Dis-placement occurs between the two inner surfaces, which are in direct contact with each other. This is because one of the two surfaces is being stretched while the other is being compressed. If both sheets are laminated with an adhesive polymer interlayer,this must be able to internally compensatefor the distortional differences (i.e. absorbshear forces)….