Thermoplastic benefits for E-bikes

Commingled carbon fibre and nylon
yield improved fibre deposition for maximum performance.

The UK\’s National Composites
Centre (NCC) has worked with Bristol-based Starling Cycles and Composite
Braiding of Derby to demonstrate the use of thermoplastic carbon fibre for an
electric mountain bike frame to be repaired and recycled at the end of life more easily.

Whilst composite bikes are
already readily available, they are mostly made from thermoset epoxies, which,
because they are resistant to heating, cannot be broken down and repurposed at the end of life. To counteract this, the project team developed a frame
for an electric bike using thermoplastic carbon fibre.

Thermoplastics can soften when
heat is applied to them and can be re-shaped, which means that they can be repurposed if needed and can be significantly repaired throughout
their use, increasing their lifespan.

The demand for E-bikes in Europe
is expected to grow significantly in the coming years, with anticipated sales
increasing from 3.7 million bikes in 2019 to 17 million in 20301. Currently,
Starling Cycles manufactures its handmade E-bike frames from steel. By using a
thermoplastic composite frame instead, the range of the bike will be increased
due to the weight reduction, as well as offering a more sustainable product.

As well as conducting a life
cycle assessment (LCA) of Starling Cycles\’ existing manufacturing methods and
the frame design, the NCC developed a novel manufacturing process to create the
lugs required to hold the frame together.

Using a commingled material of
carbon fibre and nylon, the new method facilitates an improved fibre deposition
for maximum performance. Commingled materials combine the fibre and resin into
a single material, removing the need to infuse the resin layer separately in manufacturing, making it more efficient.

The LCA allowed Starling Cycles
to ascertain where future improvements can be made to its design and
manufacturing process to make further reductions to the product\’s environmental impact.

In addition to showing that
thermoplastics are a strong enough material to be used for a bike frame, the
expanded understanding of how they can be re-worked and re-used opens the door
to using thermoplastics in other components across the industry due to the
flexibility they offer. They can also provide higher production rates (due to the
lack of separate infusion processes) whilst still providing high-quality composites, potentially reducing costs and environmental
impact.

Source: nccuk