technology | Materials
Gas pipe can deteriorate if left in the sun for too long, says Kiwa
heat-resistant version of PVC. “Its advanced thermoplastic properties overcome the
Vicat limitations of PVC,” he said. The first grade is Thermavic ET292/0900, with a
Vicat of 92°C, for both indoor and outdoor applications. Like other Thermavic grades, it can be processed on conventional PVC extrusion lines. A gravimetric feeder is recommended for optimal dimensional tolerance of profiles, while high shear rates are needed – so twin-screw machines are preferred. The maximum recommended processing temperature is 185°C.
Stable performance US-based AM Stabilizers has developed a new family of barium/zinc liquid stabilisers for flexible PVC. The company’s PlastiStab 2528 and 2534 are free of alkyl phenol – which may soon be added to Reach’s can- didate list of Substances of Very High Concern (SVHC). This is a list of substances that could have a serious effect on human health. “Articles containing an SVHC above 0.1% require
certification to ECHA and communication along the supply chain,” said Benjamin Labovitz, R&D manager at the company. The two grades contain no nonyl phenol – making
them currently Reach-friendly. At the same time, an absence of alkyl phenol makes them ‘Reach-friendly in the long-term’, he said. The grades have 28 and 34% barium content, respectively. He said that testing had shown that the new formula- tions had sufficient thermal stability and physical characteristics to compete with existing grades.
Sun protection IQAP of Spain has developed a range of cold master- batches for PVC profiles and sidings. It says that the materials are based on ‘smart’ technology that reflects
50 PIPE & PROFILE EXTRUSION | July/August 2016
sunlight – especially infrared radiation –in order to minimise surface temperatures. It was tested for heat build-up (HBU), by exposure to a 250W heat lamp until thermal equilibrium is achieved. For medium coloured samples, the ‘cold’ masterbatch achieved a surface temperature reduction of 11-12°C; for dark coloured samples, the reduction was 37°C. “It allows manufacturers to extend the life of the
polymer matrix, and decrease heat stress on the mate- rial,” said Marta Ortiz, a PVC specialist at the company. In similar vein, Jeroen Weller, a consultant at testing
company Kiwa in the Netherlands, said that the influence of sunlight on PVC gas pipes should be taken into consideration – especially with regards to its effect on impact resistance. He said that tests showed a clear difference between
the ‘sun side’ of a PVC sample compared with the ‘shadow side’. “After three months, there is already some deterio-
ration in impact resistance,” he said. “Discoloration is also clearly visible.” He said that exposure to sunlight should be mini- mised during installation – such as by keeping PVC inside its plastic sheeting for as long as possible, and by keeping pipes ventilated to minimise temperature. “Some days or weeks of weathering does not really
affect impact resistance, but some months do,” he said. l Proceedings from the conference are available from Giulia Esposito (
ge@amiplastics.com) on +44 117 314 8111, or from this link.
Click on the links for more information: ❙
www.amiplastics.com ❙
www.crayvalley.com ❙
www.benvic.com ❙
www.amstabilizers.com ❙
www.iqapgroup.com ❙
www.kiwa.nl
www.pipeandprofile.com
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