Silk production explained

A better understanding of how silk is spun in the natural world could lead to greener ways of producing synthetic fibres according to scientists at the University of Sheffield.

The team discovered that animals spin silk by pulling, not pushing it out of their bodies. If this could be replicated in an industrial setting, it could improve synthetic material manufacture as well as being more environmentally-friendly.

Silk’s possibilities

Jamie Sparkes, lead author of the study, said: “Silk is one of the most promising green biomaterials, and could be the perfect replacement for nylon and polyester based clothing. Traditional production process for silk is both arduous and time-consuming, but if we can bypass that by mimicking nature in an industrial setting, we could improve not only silk but also how we process our synthetic materials."

Synthetic textiles are made by extrusion – pushing liquid feedstock through a dye – before applying high temperatures and harsh chemicals to solidify it. Silk can solidify into a fibre at room temperature, leaving only water and therefore much more environmentally friendly.

The researchers combined computer models with experimental data and practical measurements to determine the force needed to form a silk fibre. They found that a silkworm would have to squeeze itself hard enough to generate more pressure than a firing diesel engine. However, the silkworm was able to produce enough force to pull a fibre, a process they have named pultrusion.

The research was published in Nature Communications.