Team develops EV chargers using wood-plastic composite

A team at the Fraunhofer Institute for Mechanics of Materials in Halle hopes to replace the steel cladding that protects cables, power outlets and electronic switchgear with honeycomb panels made from the composite material.

Wood-plastic composite is a natural fibre composite made up of 70 per cent cellulosic wood fibre and 30 per cent thermoplastic polypropylene. It can be repeatedly recycled and is primarily used for weather-resistant decking for patios.

‘Trees extract huge quantities of carbon dioxide from the atmosphere as they grow and sequester carbon in their ligneous fibres,’ said Sven Wüstenhagen, one of the IWM researchers in Halle.

‘It is therefore probable that the use of WPC in this new application will result in lower CO2 emissions compared with the use of steel.’

Another advantage of the composite material, according to Wüstenhagen, is that its production is more energy efficient than that of steel or other metal cladding materials.

‘This is a viable proposition because WPC can be formed into almost any shape, unlike the metal sheeting used in currently available housings,’ he said.

‘They could [also] be used, for instance, to construct street furniture such as park benches or bus shelters. That’s one of our next objectives.’

WPC is produced using an extrusion process that involves melting a mixture of wood fibres and thermoplastic resin under high pressure and at high temperature and feeding the resulting viscous product into a continuous mould.

With modern processing technologies, the fibres can be added to the mixture in their natural state, without first being transformed into granulate, thus eliminating an energy-intensive intermediate stage and preserving the quality of the fibres.

Because wood has a high thermal sensitivity, it has to be processed at temperatures below 200ºC.

The housings are manufactured in the form of modular components that can be clipped together as required to create a wide variety of designs, allowing them to blend in with the surrounding architecture.

The WPC needs to be shatter proof and sufficiently elastic to withstand impact without damage, and it must be capable of resisting wide variations in temperature, high levels of humidity and prolonged ultraviolet exposure.

The researchers are therefore testing samples of the material in a climate chamber to assess its resistance to extreme temperature conditions and to determine which additives or types of coating provide the best weather protection.