Turning up the heat
The growth of the composites industry is seeing some very interesting new applications arise for nonwovens – and not just as fabric reinforcements for composite parts.
In combination with conductive carbon-like additives, for example, the composites are now serving as de-icer units and even as temperature control systems for pressurised fuel containers.
Dutch company Lantor already supplies conductive nonwovens for the cable industry so its development of an electrically-conductive material – created by laminating strips of a carbon-like conductive additive and electrodes to a substrate – was a logical development.
The key to the development of PowerSHEAT was in retaining the material’s conductive properties once impregnated with polyester or epoxy resin systems, as required for use in composite applications. This has been successfully achieved – the heated nonwoven works well at both low voltages of below 100 volts and at over 230 volts and can achieve up to 2kW/m2 of power.
This power and the variable voltages make a wide range of applications for PowerSHEAT possible, including the de-icing of floor plates, the heating of tooling systems and the curing of the bonding connections in glass fibre epoxy pipes.
In an initial project, the material was employed in composite entrance ramps which can become slippery due to snow and ice. To prevent build-up, Lantor developed an integrated heating system, together with its electronics partner Huikeshoven and the producer of the ramps, UTEC Composites.
The heating system can be plugged into an ordinary power supply and the electrical heating of the ramp is regulated to turn on when the outside temperature goes below 6°C and turn off again when it rises to over 12°C. A safety sensor is also integrated to prevent over-heating.
More recently, Lantor has teamed up with fellow Dutch company Tankwell to provide a similar temperature control system for composite tank containers.
Tankwell has developed a one-step filament winding process for manufacturing fibre reinforced vessels which conventionally have been made from stainless steel. Composites, however, provide both lower weight and improved thermal properties and Tankwell’s manufacturing process allows strength and low weight to be further optimised compared to other processes. In addition, the PowerSHEAT nonwoven layer can be integrated into the vessel during manufacturing.
The overall result is a weight reduction of between 25-40% compared to steel vessels and a 40% improvement in thermal performance when compared to metallic tank containers with Tankwell’s Swap Body Tank Container and average fuel savings of 3% per cubic metre of liquid being transported.
A test phase for the Swap Body Tank Container was carried out by the Hamburg-based logistics specialist Hoyer and proved highly successful. In October 2014, Hoyer put into operation its 15th Tankwell composite tank and a month later received the BASF Global Supplier Award 2015 in the sustainability section.
BASF has been the first user of Hoyer composite tanks and is now looking to expand their use.
“The composite tanks have already been operating on certain selected routes since early 2015, and have now successfully completed more than 500 trios,” said Hoyer’s Director of Equipment Management Ulrich Graupe. “They have a weight of just 2,200 kilograms with a 31,000 litre capacity, making their load capacity of composite containers about two tons larger than conventional steel tanks. This is made possible by the special composite material that also has good thermal properties and reduces heating processes.”
Thermal properties can now be further optimised by the incorporation of the PowerSHEAT nonwoven layer.
“We save both energy and transport costs by using the composite tanks and we reduce the number of traffic movements through their high load capacity,” Graupe conclude. “As a consequence we are lowering the CO2 emissions of our transport operations.”
Expect to see many more nonwoven innovations with applications in the rapidly-growing composites sector at the next INDEX nonwoven show which takes place in Geneva, from April 4-7 2017.
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