Redefining textiles

New materials and manufacturing processes give the word “textile” new meaning.

Textile technology is undergoing a revolution, with innovative structures, raw materials and manufacturing platforms creating new fabrics that defy old-school definitions. Introductory textile science classes teach that textiles are materials that can be woven, knit, crocheted, knotted or felted from yarns spun from cellulose, protein or petroleum-based synthetic fibers. Today, the creation of a new generation of consumer textiles is being driven by trends such as digitization, customization, sustainability, performance and speed-to-market.

Additive manufacturing models, including three-dimensional (3-D) knitting and printing, molding, bonding and lamination—along with a raft of new raw materials, such as biosynthetics, foam and composite structures—are disrupting the known world of textiles, creating a knowledge base that is rapidly expanding from consumer products into products and applications in the wider world.

The ruckus over the skeleton suits worn by the Great Britain and Northern Island Olympic Team (Team GB) at the 2018 PyeongChang Winter Olympics brought home the fact that this new breed of textiles is, indeed, extraordinary. Developed by U.K.-based engineering consultants TotalSim and the English Institute of Sport, the skeleton team’s “skinsuits” were made from a polyurethane derivative. Each athlete was custom-fitted via a 3-D laser scan. Because the suits featured aerodynamic ridges that reduced wind resistance, some competitors thought this was outside the scope of Olympic rules about aerodynamic designs.

The new knits

The launch of knitted shoe uppers by Nike and adidas in 2012 raised the bar for athletic footwear design and fueled the development of new methods of manufacturing that eliminated steps in the supply chain and reduced material waste. The flatbed knitting machines used to create footwear uppers employed digital design to customize complex dimensional knit structures, instead of knitting individual pieces that required sewing. The technology is now being adopted for use in areas such as architecture or automotive applications.

For example, in 2017 home furnishings retailer IKEA launched 3-D knit chairs using the new knitting technology. Bloomberg News recently reported that the Japanese company Shima Seiki Mfg. Ltd., which pioneered digital WHOLEGARMENT® knitting, is in talks with major auto parts suppliers to develop lightweight knit components that could replace steel.

But there’s more. Reebok’s Flexweave™ was designed as a woven structure for lightweight, breathable, customizable shoe uppers. The unique open figure-8 construction integrates raw materials, such as chenille yarns for softness and thermoplastic elastomer (TPE) yarns for lightweight stability, with the potential to add spandex or high-tenacity fibers such as Kevlar® to the mix. Flexweave woven fabric is now being engineered into a classic suit, an athletic chair, gloves and a training mask.

Working with Shima Seiki WHOLEGARMENT 3-D knitting machines and photoluminescent, solar-active and recycled yarns, architect Jenny Sabin created structures that were exhibited at the Cooper Hewitt Design Triennial in 2015–2016, and at the Museum of Modern Art (MoMA) PS1 in Long Island City, N.Y., in 2017. Sabin’s Lumen installation, comprising thousands of digitally knitted cells in stalactite conical forms, won MoMA’s 2017 Young Architects Program.

Reimagining materials

Raw material innovation is also moving at an unprecedented pace. Materials like biosynthetic polymers, derived wholly or in part from renewable resources such as sugars, starches and plant oils; biomass from cellulosic plant waste; or algae, fungi or bacteria, are forecast to comprise 22 percent of all chemical sales by 2020, according to the European Commission. With sustainability top of mind, the potential of biosynthetics is worth further exploration.

While foam has become somewhat ubiquitous as a component of footwear, home furnishings and protective equipment, recent developments in a polymer known as thermoplastic polyurethane (TPU) from chemical companies such as BASF, Huntsman and Lubrizol Corp. are also changing the game.

TPUs are extremely versatile, exhibiting elasticity and durability, and can be melt-processed, making them useful for footwear components and performance textiles. Most important, they can be blown into foam, creating a lightweight, easily processed material recommended for midsoles and other end uses where weight, cushioning, impact resistance, insulating qualities and breathability are key.

Ohio-based Lubrizol’s BounCell-X™ is a low-density, plasticizer-free, recyclable foam made from Lubrizol’s Estane® BCX TPU. Kenneth Kim, Lubrizol North American market development manager for footwear, describes the manufacture of BounCell-X as a clean process, which employs nitrogen gas as a physical blowing agent to create a microcellular foam. The process leaves no chemical residue within the polymer, allowing the product to be recycled within the original polymer classification.

Abrasion-resistant materials similar to rubber can be formed from another material, Lubrizol’s Estane TPU TRX, which is compatible with “over molding” of softer BounCell-X foam components, eliminating the need for solvent-based adhesives in footwear and other manufacturing processes. In addition, Lubrizol’s Esdex® TPU yarns can be knit or woven in shoe uppers or other textiles, and thermally customized for different levels of flexibility, comfort and reinforcement.

“The ‘green’ story is huge,” says Lalith Suragani Venu, Lubrizol’s application scientist in performance apparel and footwear. While traditional foams must be cut to shape and require the use of cements or adhesives during manufacturing, “Lubrizol TPU foams and yarns can be bonded or customized through thermoforming, while maintaining flexibility, breathability and antibacterial properties.”

3-D printing pros and cons

TPU’s strength and elastomeric properties are finding additional application in the development of materials for 3-D printing. Lubrizol recently announced a collaboration with HP in its Open Materials and Applications Platform to explore the development of its Estane TPU polymers in fused deposition printing processes.

3-D printing (3DP), which deposits or “prints” layers of a raw material from a digital program, has been touted as the future of textiles. Footwear brands including adidas, Nike, New Balance and Under Armour have already successfully adopted 3DP for components in their athletic shoes.

High-end designers such as Iris van Herpen and Gabi Asfour have launched 3DP apparel on the runway. But unlike traditional woven or knit textiles that allow yarns to slip and move within the structure, 3DP fuses the raw materials together, making garments stiff, scratchy and brittle. Until recently, development of raw materials for 3DP with the flexibility and robustness needed for apparel has been slow.

Designer Danit Peleg has been advancing the progress of 3DP textiles since her 2015 graduate collection of 3DP garments for Shenkar College of Engineering, Design and Art garnered international attention. Peleg’s breakthrough came when she found Filament FilaFlex®, a flexible 3DP filament created by Spanish company Recreus made from TPE.

The inspiration for Peleg’s lacelike structures came when she connected with Andreas Bastian and his mesostructured cellular materials. The geometry of Bastian’s 3DP mesostructures increases their ability to stretch or compress, relying on structure rather than raw materials for their flexibility. Adapting Bastian’s structures enabled Peleg to develop 3DP fabric with the necessary flexibility to create wearable garments.

“When you touch my fabric, it is not like anything you have felt before. It’s so similar to ‘real fabric.’ For me, it is real fabric,” she says.

Peleg credits a creative partnership with Gerber Technology, a Connecticut-based supplier of hardware and software to numerous industries including fashion, with enabling her to create the digital patterns for her designs. She’s worked with Gerber to improve its AccuMark® pattern-making and 3-D visualization software.

Peleg says the plastic polymers used can easily be recycled at home. A Vermont-based company called Filabot makes desktop extruders that melt plastic waste, such as a cut-up 3DP dress or scrap material, then extrudes it as usable filament for the next project, enabling fast-fashion addicts to 3DP a garment at home for “one night only” and then recycle it.

Bastian envisions other end uses for his 3DP structures as well, offering architects more flexibility in the variety of curved surfaces with which they could compose a building’s facade. “Likewise, composite body panels used in boat hulls and automotive bodies could be fabricated using mesostructures as the core material, enabling more complex curvature,” he says.

From knitted footwear and architecture to future materials and 3-D printing, these new definitions of “textiles” will challenge the industry at large to keep pace.

Debra Cobb is a freelance writer based in Greensboro, N.C., with extensive experience in the textiles industry. She is a regular contributor to Advanced Textiles Source.