The UK's Fibre Extrusion Technologies (FET) is launching a significantly more sustainable, cost-effective, and highly flexible process for producing critical fibers made from ultra-high molecular weight polyethylene (UHMWPE).

Unbeatable properties

UHMWPE is highly valued across many industries because of its exceptional properties. For instance, the fiber is ten times stronger than steel by weight and boasts remarkable abrasion resistance, low friction, and high impact strength. UHMWPE fibers are also chemically inert, resistant to most chemicals and UV light, and do not absorb water. They maintain their performance across a wide temperature range and, despite their toughness, are incredibly lightweight. Consequently, they are unmatched in demanding applications such as high-performance ropes for maritime, industrial, and rescue uses. Furthermore, they are invaluable in ballistic protection, cut-resistant clothing, high-performance sports gear, and are increasingly being used in medical implants.

Biomedical market

FET has supplied numerous extrusion systems to the biomedical market, particularly for producing both resorbable and non-absorbable sutures," explains FET Managing Director Richard Slack. "In exploring how we could further assist these customers, we identified a clear demand for smaller quantities of UHMWPE fibers in custom sizes.

The existing systems for manufacturing UHMWPE filament yarns operate on a massive scale with highly intricate processing routes," explains Research and Development Manager Jonny Hunter. "This results in a very inflexible supply chain, offering minimal chances for new product development. We've fully addressed these drawbacks with the development of our new FET-500 series lab and small-scale gel spinning system.

Solvent extraction

A significant innovation from FET is their patented batch system, which utilizes supercritical carbon dioxide (CO2) for solvent extraction. Previously, UHMWPE production relied on large quantities of hazardous solvents like dichloromethane (DCM) or hexane. In that process, UHMWPE powder is combined with mineral oil to create a gel, which is then extruded, cooled, and solidified. The oil is subsequently extracted from the fibers using DCM or hexane, and the solid fibers are then drawn at high temperatures to further align the polymer chains, resulting in the final strong and tough fibers. Typically, ten kilograms of hexane are needed to extract one kilogram of oil.

"Reclaiming solvent with extraction baths and hot air-drying chambers just isn't practical for the scale of our system," explains Kris Kortsen, FET's senior material and process scientist. "The baths currently used can be up to 200 meters long, and the waste volumes are considerable. Expertise is needed to handle such dangerous chemicals, and overall, the process has a huge environmental impact. CO2, however, is a cheap, abundant, and sustainable solvent that's non-toxic, non-flammable, and leaves no residue."

Closed loop

FET's closed-loop system boasts over 95% solvent recovery without compromising performance, delivering residue-free UHMWPE filament yarns through a significantly safer and more logistically sound process. Additionally, a notable innovation is their highly modular drawing system, which uses heated godet rollers. This allows for flexible temperature and drawing control, facilitating new product development and offering the ability to expand as customer needs evolve.

Having processed over 130 different polymers while developing our extrusion systems, we truly believe the FET-500 is a game changer," concludes Richard Slack. "We see a significant gap in the market for smaller quantities of UHMWPE, and our first line is now fully operational at the FET Fibre Development Centre in Leeds. We're excited to demonstrate it and discuss its full potential with interested companies from around the world.