SGP laminated glass VS DG41 laminated glass

SGP laminated glass is short for SentryGlas Plus interlayer laminated glass.It’s world known high performance interlayer developed by Dupont ,which was acquired by Kuraray in the end of 2014.

The features of SGP interlayer is high strength.SGP laminated glass bearing capability is 2 times that of PVB laminated glass,but the bending deflection of SGP laminated is only 1/4 of PVB laminated glass under the same thickness and load condition.

The tearing strength of SGP interlayer is 5 times higher than PVB film,even if the glass breaks,the SGP can also stick the glass and form a temporary structure while keeping small bending deformation,it can withstand a certain amount of load and whole piece laminated glass won’t fall or deform.

Features of SGP laminated glass:

  1. It has high bonding ability to glass and strong tear strength, which can prevent the glass from breaking and scattering.
  2. It has strong protective ability, can prevent natural disasters and human damage, and has sufficient resistance to strong winds, earthquakes, violence, theft, etc.
  3. It can withstand the sudden impact of indoor personnel, prevent the glass from scattering or the whole out, and avoid indoor people and articles flying out and falling.
  4. There is enough residual bearing capacity, and the whole piece will not fall off when the glass breaks and then bends.
  5. SGP film has sufficient shear modulus to bend the entire section of the laminated glass, improve the bearing capacity and bending rigidity of the glass, and reduce the glass thickness and glass weight.
  6. Can withstand the effects of ultraviolet light, water vapor and external climate change, long-term use will not appear yellowing discoloration.

Taking advantage of SGP laminated glass high strength ,it’s widely used in hurricane proof windows&doors,bulletproof glass,glass aquarium,oversized architectural glass, glass floors,glass skywalk and glass bridges worldwide.

DG41,full name is Saflex DG structural interlayer,developed by Eastman Group,another world leading PVB manufacturer.The features of DG structural interlayer is,beside offering higher strengthen than normal PVB laminated glass,it is applicable to other Saflex brand PVB interlayer products ,which allows glass processors to use both normal products,for example RA,RB,Vanceva PVB interlayers and DG41 structural interlayer can be used in the same laminated glass,this can decrease the processing difficulty and increase the finished glass ratio,makes glass colorful and multi-functions.

For this reason,many designers appoint DG41 laminated glass in their project ,and sometimes even replace the SGP laminated glass,it’s not suggested to make this decision before confirming the glass strength and the local temperatures and climate.

Designers use some formula to calculate the laminated glass strength and usually ignore the interlayers function &strength,laminated effective thickness is used.With the development of new structural PVB&SGP interlayer, laminated effective thickness is no longer effective,and designers need to consider the function of this stiff interlayer function in the designing process.

What decided the interlayer strength?

The shear modulus describes the material’s response to shearing strains.A lateral deformation is observed in the object when a shear force is applied to it. The elastic coefficient is known as shear modulus of rigidity.  Shear modulus rigidity is the measurement of the rigidity of the object and it is obtained by measuring the ratio of shear stress of the object to the shear strain of the object.

Below show the shearing modulus of SGP interlayer and DG41:

As we can see,DG41 shearing storage modulus is very similar to Kuraray Extra stiff PVB interlayer,so we can see them same products.the shearing modulus decrease significantly and sharply once temperature over 30 degrees,and almost same as normal PVB interlayer when temperature going higher.

But how can we see the difference of different shearing modulus when the interlayer was applied into laminated glass? It’s quite easy, let’s check whether the laminated glass can be penetrated or not, and another important point ,is if the laminated glass can sustain certain weight after broken.

Mr Malvinder Singh Rooprai&Ingo Stelzer,conducted a test against the laminated glass because even though the FEM software can help calculate the glass pre-breakage strength,it cannot predict the post breakage strength ,even in the cases maintenance workers falling through or falling down.

The test was based on German Standard pr DIN 18008-6 covering PVB,EVA,SGP interlayer and stiff interlayer (Kuraray sextra stiff) ,and in 3 temperature conditions:subzero (-20 °C), room temperature (21 °C) and elevated temperatures of 50 °C,through this test,the scientists were able to know clearly which kind of laminated glass can work as the best materials used in overhead glazings,for example glass floor,glass bridges,glass skywalks etc.

1.. Immediate Post Breakage Strength against “fall through”

Dropping a soft bag weighing 100 Kgs (typical weight of maintenance working along his tools and tackles) from a height of 1.2 mts at a test temperature of 50 ºC. The test method simulates potential loading from installation and/or maintenance workers in distress. The panels were conditioned at 50 °C for 1 hour before the test.

The test result shows that SGP laminated glass didn’t collapsed and prevented the soft bags falling down,while EVA ,normal PVB and stiff PVB laminated glass all collapsed as soon as the impactor struck,and failed to act as a barrier.

  1. Medium Duration Post Breakage Strength Testing (30 Minutes or more)

The Germany Standard DIN 18008–6, (Glass in Buildings – Design & Construction Rules – Additional requirements for walk-on glazings in case of maintenance procedures),is the only world existing standard to evaluate the glass sustain capability after breakage.

The standard requires a laminated glass construction to sustain the weight of 100 Kg for at least 30 minutes after breakage of top layer of glass.

First, the panel is subjected to an impact made by dropping a twin tyre impactor which weighs 50 Kg from

a height of 900 mm. This is followed by imposing a load of 100 Kg for 30 minutes on an area of 200 x 200 mm (Fig. 7). After breakage of the uppermost glass layer, the whole glazing element must stay on its supports for at least 30 minutes.

The test was aimed to know the ultimate post breakage performance limit so load was ramped up to 400 Kg in increments of 100 Kg, with a 15 minute time interval between each load increment.

At -20 °C, laminates made from the 4 interlayer candidates i.e 0.89 Ionomer, 1.52 mm Ionomer, 1.52 mm PVB, 1.52 Stiff PVB pass the post breakage strength requirements of the new German Standard pr DIN 18008 – 6.

  1. At -20 °C, all 4 candidates had their ultimate strength more than 400 Kg as there was no collapse of the panel due to tearing of the interlayer at rotules.
  2. At 21 °C, Ionomer and Stiff PVB laminates pass the post breakage strength requirements of DIN 18008–6 but PVB laminate does not.
  3. At 21 °C, 0.89 mm & 1.52 mm Ionomer laminate had almost similar post breakage strength till about 45 minutes from the breakage.
  4. For tropical climate regions where the ambient temperature is more than 45 °C, Ionomer interlayer laminates meet and exceed the requirements of pr DIN 18008-6 Standard.

The test report can be get here:Test report

Please also contact us if you’re interested in the full test videos.

Based on above test,we can see that SGP laminated glass can work as good barrier against falling accident,and can sustain up to 400kgs weight for up to 45 minutes even if glass is broken.

While extra stiff PVB laminated glass,whether it’s Kuraray extra stiff,or DG41 interlayer,when under high temperature conditions,the laminated glass cannot protect people once accidents happens and cannot sustain much weight,this match the shearing modulus chart above.

DG41 ‘s shearing strength decrease sharply and almost same as normal PVB interlayer,which means its strength and sustain capability is almost same.So it’s not suggested to use DG41 and stiff PVB laminated glass in areas where the temperature is over 30 degrees,so interior application,and high tropical areas is perfect for extra stiff products.

SGP interlayer works in anywhere,whether it’s high temperature or low temperature.

 DG41 and SGP laminated glass Price.

1.52mm DG41 price is about USD45/SQM.

1.52mm SGP price is about USD54/SQM.

Let’s take 21.52mm low iron tempered laminated glass as example,the price with DG41 and SGP interlayer price is about USD95 and USD105/SQM.

The final price difference is decided by the interlayer difference.There’s almost no processing costs difference.

Morn is your turnkey laminated glass manufacturer and supplier in China,welcome contact us if you got any questions and any laminated glass requirement.

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