Researchers at ETH Zurich, one of the leading international universities for technology and the natural sciences, have developed a yarn from ordinary gelatine that has good qualities similar to those of merino wool fibres. Now they are working on making the yarn even more water-resistant, the University said on its website. Some 70 million tonnes of fibres are traded worldwide every year. Man-made fibres manufactured from products of petroleum or natural gas account for almost two-thirds of this total. The most commonly used natural fibres are wool and cotton, but they have lost ground against synthetic fibres. Despite their environmental friendliness, fibres made of biopolymers from plant or animal origin remain very much a niche product. But over the past few years, there has been increased demand for natural fibres produced from renewable resources using environmentally friendly methods.Now Philipp Stössel, a 28-year-old PhD student in Professor Wendelin Stark’s Functional Materials Laboratory (FML), is presenting a new method for obtaining high-quality fibres from gelatine. The method was developed in cooperation with the Advanced Fibers Laboratory at Empa St. Gallen. Stössel was able to spin the fibres into a yarn from which textiles can be manufactured. Gelatine consists chiefly of collagen, a main component of skin, bone and tendons. Large quantities of collagen are found in slaughterhouse waste and can be easily made into gelatine. For these reasons, Stark and Stössel decided to use this biomaterial for their experiments. In his experiments, Stössel noticed that when he added an organic solvent (isopropyl) to a heated, aqueous gelatine solution, the protein precipitated at the bottom of the vessel. He removed the formless mass using a pipette and was able to effortlessly press an elastic, endless thread from it. This was the starting point for his unusual research work. As part of his dissertation, Stössel developed and refined the method, which he has just recently presented in an article for the journal Biomacromolecules. The refined method replaces the pipette with several syringe drivers in a parallel arrangement. Using an even application of pressure, the syringes push out fine endless filaments, which are guided over two Teflon-coated rolls. The rolls are kept constantly moist in an ethanol bath; this prevents the filaments from sticking together and allows them to harden quickly before they are rolled onto a conveyor belt. Using the spinning machine he developed, Stössel was able to produce 200 metres of filaments a minute. He then twisted around 1,000 individual filaments into a yarn with a hand spindle and had a glove knitted from the yarn as a showpiece.
