Materials
“The Olympic Delivery Authority (ODA) take safety very seriously, so we had to do lots of physical testing,” he says. “I was pleasantly surprised that our boards performed so well.” There was also a need to redesign the panels slightly,
for safety reasons. “The organisers didn’t want debris falling through
the gaps - in order to minimise the risk of fire - so the boards had to be redesigned,” says Collins. Working with stadium designer Populous, the
company redesigned the edges so that they were ‘S’ shaped - allowing an overlap. This closed the gap to debris and litter, but still allowed rainwater to drain through.
In a one-month production surge, Vannplastic
produced 110 tonnes of decking. The decking area accounts for around 10 per cent of the Olympic stadium’s circumference. And it’s not just wood fibres that can strengthen
plastics in this way. Researchers at the Universiti Teknologi Mara in Malaysia have created a new type of WPC using a polypropylene (PP) matrix with fibres from the kenaf plant. They say that their new composite materials have higher performance and durability than existing alternatives. Their study assessed the use of powdered kenaf
core fraction (which makes up about 65 per cent of the whole stem of the plant) as a filler material. Kenaf stems contain two fibre types, called bast
and core. Dosing with a compatibiliser strengthened the bond between the ground kenaf core (GKC) and plastic in the WPC. This improved stress transfer and increased strength and stiffness, allowing more filler to be used. Reducing the amount of plastic while increasing the amount of GKC - without sacrificing strength, stiffness or durability - would result in ‘greener’ WPC products. WPCs of PP and GKC fibre, dosed with
compatibiliser in the right amount, bridged the interface between GKC and plastic, improved stress transfer and increased strength and stiffness - as well as allowing a higher filler loading of 65 per cent.
Panel game
There are many reasons for choosing natural fibre reinforcements. They may be readily available, and offer clear benefits (as in the case of wood fibres for WPCs); they can also help to reduce the carbon footprint or recyclability of a product, which is becoming more important. At the same time, the polymer itself may be
bio-based - so using a naturally sourced filler or reinforcement makes perfect sense. A good example of this is in the pan-European
Cayley project, which aims to develop panels for the transport sector based on renewable polymers and natural fibres. The panels, which are used as sidewalls, ceilings, fairings and overhead lockers in applications such as aircraft, buses, ships and trains, are usually made from materials like phenolic resin and glass fibre. The project partners - Boeing Research and Technology Europe, Aimplas of Spain, Invent of Germany and Lineo of Belgium - intend to replicate the panels using more sustainable materials, while creating a commercially viable manufacturing method. At the recent JEC Europe event in Paris, project
Fig. 2. Malaysian researchers say their new type of WPC, which uses a PP matrix and kenaf fibres, is stronger and more durable than existing alternatives.
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co-ordinator Maik Wonneberger of Invent said the panels were likely to be made from polymers based on linseed oil (rather than petroleum), and natural fibres
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