materials | Waterproof membranes Right: One project
carried out by TechnoNicol was refitting the roof of the Spartak
Moscow football stadium
the same manner as expansion joints. Most recently, it has used LogicRoof V RP PVC
membrane with a high strength polyester reinforcement to cover the roof of Samara Airport. Here, the roof has a complicated shape, and is also affected by hail and the effect of passing jet engines. The membrane is 1.8mm thick (for high hail resistance and longevity).
Polyolefin alternative For roofing membranes, the choice is usually between PVC and polyolefins. For Cytec Solvay, which supplies a range of stabilisers, polyolefin membranes are superior for a number of reasons – including weathering advantages, physical properties, lower weight and barrier properties. “There are multiple applications for PP, TPO and PP in this segment,” said Ivan Vulic, senior applications manager at Cytec Solvay in the Netherlands, adding that the use of both TPO and PVC membranes are rising in Europe.
He described how Cyasorb Cynergy B877 UV
stabiliser helped to boost the properties of outdoor polyolefin membranes – in applications ranging from geomembranes to outdoor sports surfaces and siding. Cytec’s latest stabiliser, B878T, also boosts thermal
performance (as well as UV performance). The company says that it exceeds specifications for weathering and high temperature thermal exposure while protecting physical properties with high crack resistance on UV exposure – as well as being resistant to discoloration. A series of tests were carried out on TPO-based
formulations, according to ASTM D571. This included oven ageing at 116 and 138°C, plus tensile and colour measurement testing. These showed: no cracks on the TPO sheet; physical property retention beyond the requirements of ASTM; colour retention; and a UV resistance beyond that required of ASTM. Vulic explained why tests at elevated temperatures
30 FILM & SHEET EXTRUSION | May 2017
were carried out. “A roof may be hotter than 90°C due to location, design or radiant heat from other areas,” he said. “There are also new markets for roofing emerging in hot or desert climates.” Hendrik Flessner, head of product management at German distributor Ter Hell, said that the use of an advanced formulation – using polyolefin elastomers and magnesium hydroxide – had helped it to design an improved bituminous membrane. One layer of the membrane will include, among other things, the bitumen itself along with the polymer and additives. This layer is known as polymer-modified bitumen (PmB). Flessner said that using Vistamaxx PP-based
plastomer from ExxonMobil as the polymer extended the properties of the membrane – such as by having a distinct viscosity, low hardness, good flexibility and high mechanical strength. In a test against other polymers, Vistamaxx showed a
shorter dissolution time, higher viscosity at similar dosage and better cold bend performance. At the same time, magnesium hydroxide was added as a flame retardant – which was more effective when incorporated into higher-viscosity Vistamaxx. “Vistamaxx 6202 was the most suitable grade due to good balance between viscosity and cold bend behav- iour,” said Flessner.
Click on the links for more information: ❙
www.fdt.de ❙
www.concretecanvas.com ❙
www.protan.com ❙
www.swisspor-gruppe.com ❙
www.empa.ch ❙
www.milliken.com ❙
www.technonicol.com ❙
www.cytec.com ❙
www.terchemicals.com
www.filmandsheet.com
PHOTO: BRATEEVSKY VIA WIKIMEDIA COMMONS
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