Coating and Laminating News

In the run up to the conference we will be posting regular news items. Keep up-to-date with textile coating and laminating news on the TCL2019 website.

12 December 2018

First-of-its-kind carbon fibre recycling partnership is established

Boeing and ELG Carbon Fibre are working together to recycle waste aerospace-grade carbon fibre-reinforced plastic (CFRP) so that it can be used by other companies to make products such as electronic accessories and automotive parts

The agreement between the two companies – the first formal supply deal between an aircraft original equipment manufacturer (OEM) and a carbon fibre recycler – will see around 454 t (one million pounds) of excess carbon fibre material from 11 Boeing aeroplane manufacturing sites being delivered to ELG’s facility in Coseley, UK, each year.

As the largest user of aerospace-grade CFRP, Boeing of Chicago, Illinois, USA, has been working for several years to create economically viable methods for recycling such materials. The company claims to have improved its production methods to minimize waste and to have developed a model for collecting scrap material.

ELG has developed a process called pyrolysis through which CFRP scrap – in the form of dry fibres, cured and uncured prepreg, and/or laminates – is heated to 400–650°C in the absence of oxygen, to burn off the matrix. The process leaves a tough and abrasive fluff of carbon fibre that maintains at least 90% of its tensile strength compared with virgin fibre. After several years of product development, ELG has managed to convert this material into a number of useful forms.

To prove that this method could be applied on a large scale, Boeing and ELG conducted a pilot project to recycle excess material from Boeing's Composite Wing Center in Everett, Washington, USA, where the wings for Boeing’s 777X aeroplane are made. Over the course of 18 months, the partners recycled around 680 t (1.5 million pounds) of scrap carbon fibre material, which was sold to companies in the electronics and ground transportation industries.

The partnership is particularly significant for ELG. The company estimates that it will have to triple the number of people it employs, from 39 in 2016 to 112 by the end of 2019. It will also allow the company to serve its customers better. The Managing Director of ELG, Frazer Barnes, says: "Security of supply is extremely important when considering using these materials in long-term automotive and electronic projects. This agreement gives us the ability to provide that assurance, which gives our customers the confidence to use recycled materials."

Boeing and ELG are currently considering an expansion of the agreement that would see excess carbon fibre material from three additional Boeing sites in Canada, China and Malaysia being recycled. Boeing’s ultimate goal is to reduce the amount of solid waste it sends to landfill by 20% by 2025.

According to 777 Wing Operations leader, Kevin Bartelson: “Recycling composites will eventually be as commonplace as recycling aluminium and titanium."

 

5 December 2018

Graphene-coated jute fibres for reinforcing composites

A method for coating jute fibres with graphene, which improves their mechanical properties and those of composites reinforced with them, has been developed by researchers at the University of Manchester in the UK

By coating the fibres in graphene oxide, the researchers have improved their tensile strength by 94% in comparison with untreated jute fibres. Further, the strength of the bond formed between the coated fibres and an epoxy resin matrix (the interfacial shear strength) is 245% higher than that formed with uncoated fibres.

Natural fibre-reinforced composites are attracting significant interest from a number of industries as a replacement for those reinforced with synthetic materials, such as glass fibres, which are produced using energy-intensive processes and are more expensive.

Jute is extracted from the bark of the white jute plant (Corchorus capsularis) and is completely bio-degradable and recyclable. It is the second most-produced natural fibre in the world – after cotton – and is at least 50% cheaper than flax and other similar natural fibres.

Jute fibres could be suitable replacements for fibres made from glass for the reinforcing of composites owing to their lower specific gravity (around 1.3, compared with around 2.5 for glass fibres) and their higher specific modulus (around 40 GPa, compared with around 30 GPa for glass fibres).

However, these fibres bond poorly with polymer matrices owing to the presence of a waxy cementing layer, which contains low-molecular weight fats, lignin, pectin and hemicellulose, on their surfaces. Further, they exhibit poor tensile strength.

By coating jute fibres with graphene oxide using a simple dip-coating method, the University of Manchester researchers take advantage of the oxygen-containing functional groups found within the nanomaterial’s molecular structure. These functional groups interact with an epoxy resin, forming a strong mechanical bond at the fibre–matrix interface. Further, flakes of graphene oxide possess an extremely high modulus that appears to stiffen the jute fibre and eliminates stress concentrations on the surface of the fibres during tensile loading, thus enhancing their tensile strength.

The researchers also experimented with a graphene flake-based coating , and while they found that its effect on bond strength and tensile strength was lesser than that of the graphene oxide coating, it did deliver the best result in terms of enhancing the Youngs modulus of the fibres.

Senior researcher on the project and the Director of Research for the North West Composites Centre at the University of Manchester, Professor Prasad Potluri, says: “This is an example of judicious combination of low-value, carbon-neutral commodity fibres with an extremely small volume fraction of high-value graphene in order to create a material system that could replace energy-intensive carbon and glass fibres in a number of lightweight structural applications.”

Researcher on the project and Knowledge Exchange Fellow (Graphene) at University’s National Graphene Institute, Nazmul Karim,  concludes: “The use of jute in automobile interiors by global car giants has been growing rapidly with a current demand of 100 kt a year. I believe our graphene-based jute fibres could play a very important role in meeting the growing demand of more environmentally friendly products for various industries.”

 

4 December 2018

Alternative to perfluorocarbon-based finishes for leather

A perfluorocarbon (PFC)-free, water-repellent finish for leather has been launched by HeiQ of Bad Zurzach, Switzerland, and DuPont Consumer Solutions of Wilmington, Delaware, USA

Footwear manufacturer Wolverine World Wide Leathers Inc of Rockford, Michigan, USA, is the first supplier to offer leather – its pig nubuck – treated with the finish, called HeiQ DuPont Eco-Led. Eco-led is an addition to HeiQ's Eco Dry range. 

According to research carried out by HeiQ, 49% of consumers think it is important that the water-repellent finishes used on the products they purchase are free from PFCs. Wolverine's Vice President of Sales and Marketing, Suzanne Johnson, says that this demand now extends to leather products.

Hexcel to buy ARC Technologies

Hexcel Corp of Stamford, Connecticut, is to acquire a supplier of electromagnetic interference (EMI)-shielding composites for military, aerospace and industrial applications, ARC Technologies Inc of Amesbury, Massachusetts (both in the USA)

Founded in 1988 and privately owned, ARC Technologies employs about 170 people across two locations in Amesbury. It specializes in combining absorptive filler compounds – including carbon, iron and nickel-coated graphite – with a proprietary blend of polymer resins to produce structural composites and thermoplastics. The resulting materials can absorb microwaves and provide protection from electromagnetic interference (EMI).  The company is expected to generate about US$50 million in revenue in 2018.  

Hexcel has agreed to pay US$160 million for ARC, and expects the purchase to be finalized in early 2019

Vapour coating method for charge-storing garments

Researchers at the University of Massachusetts Amherst in the USA have developed a method for embroidering charge-storing patterns that they claim can be applied to any garment

While many different electronic circuit components have been made small enough to be incorporated into wearable devices, until now the same could not be said for charge-storing devices. The lead researcher on the project, Trisha L. Andrew, says: “Batteries or other kinds of charge storage are still the limiting components for most portable, wearable, ingestible or flexible technologies. The devices tend to be some combination of too large, too heavy and not flexible.”

The method developed in Andrew’s laboratory employs stainless steel sewing threads that are coated with poly(3,4-ethylenedioxythiophene) chloride (PEDOT-Cl) using a reactive vapour deposition (RVD) process to increase their electrical conductivity.  These threads are used to embroider a pattern onto a textile substrate to form electrodes, which are then coated with a polymer gel electrolyte to make flexible microsupercapacitors (MSCs).

The process creates porous conducting films of the polymer on densely twisted yarns, the high surface area of which maximizes contact with the electrolyte ions and maintains high charge-storage capacity per unit length as compared with prior work with dyed or extruded fibres.

Andrew says: “We can embroider a charge-storing pattern onto any garment using the vapour-coated threads that our laboratory makes. This opens the door for simply sewing circuits on self-powered smart garments.”

Andrew notes that textile researchers have tended not to use vapour deposition because of technical difficulties and high costs, but more recent research has shown that the technology can be scaled-up and remain cost-effective.

She and her team are currently working with others at the University of Massachusetts Amherst Institute for Applied Life Sciences’ Personalized Health Monitoring Centre on pairing the embroidered charge-storage arrays with smart textile sensors and low-power microprocessors to make smart garments that can monitor a person’s gait and joint movements.

Interweaving layers to make durable fire-resistant textiles

A fire-resistant textile developed by Arville Textiles of Wetherby, UK, could be used to manufacture clothing for use by firefighters, military personnel and police officers

Outlined in International Patent Publication WO2018/150165, the textile is claimed to:

  • be lightweight, breathable and comfortable;
  • move moisture away from a wearer’s skin efficiently to reduce the risk of scalds;
  • meet the required standards of key flammability regulations, such as European standard EN 469 (Protective clothing for firefighters).

According to the Patent, the fire-resistant textile (100) comprises:

  • an outer woven layer (102) of meta-aramid fibres or a blend of meta-aramid and para-aramid fibres;
  • an inner woven layer (106) of para-aramid fibres;
  • an intermediate woven layer (104) in a blend of wool and cellulose fibres.

All of the layers can be made in a 2 × 2 twill resulting in an open interwoven structure that hides the stitching points of the lower layers, and provides a tight, dense construction that imparts high dimensional stability and increases durability to multiple washes, says Arville.

Preferably, the yarn count of the outer layer is around 72/2 Nm and it comprises 93% meta-aramid fibres (such as 1.4 dtex Nomex from DuPont of Wilmington, Delaware, USA), 5% para-aramid fibres and 2% antistatic fibres (such as carbon fibres).

The yarn count of the inner layer is around 100/2 Nm and it comprises 100% para-aramid fibres (such as Kevlar from DuPont) to provide the textile with strength and stability, particularly during heat exposure.

The yarn count of the intermediate layer is around 60/2 Nm and it can include shrink-resistant wool fibres with a diameter of 15.5–29.5 μm (ideally 20.8 μm)  in a blend of 55% wool/45% cellulose (such as a fire-retardant viscose fibre from Lenzing of Lenzing, Austria, with a titre of 2.2 dtex) to provide comfort and moisture management.

Warp ends from the inner layer are woven into the outer and the intermediate layers by crossing over individual picks.

The figure shows an open grid structure in which the warp (Wpint) and weft (Wtint) yarns from the intermediate layer are aligned with every other respective yarn (Wpout) and Wtout) of the outer layer; that is, there are around half the number of wool/viscose yarns relative to the yarns of the outer layer to define a grid structure that is more open than that of the outer layer.

The inner woven layer has an open grid structure of the same or similar density in terms of warp and weft spacing to that of the intermediate layer. However, the warp (Wpinn) and weft (Wtinn) yarns of the inner layer are each located between the adjacent yarns of the intermediate layer.

As shown in the figure, the weft yarns of the inner layer are located between adjacent weft yarns of the intermediate layer and are in the same plane. The warp yarns of the inner layer are aligned between the adjacent warp yarns of the intermediate layer while being predominantly in a different plane to them.

Further, the warp yarns of the inner layer occasionally interact with the weft yarns of both the intermediate and outer layers to hold the textile together.

When combined with a moisture barrier and inner liner for a firefighting garment, the fire-resistant textile has a fabric weight of around 250 g.m–2.

In 2017, Arville entered into a trade mark licencing agreement (TMLA) with DuPont for Nomex yarns.

Woven using Nomex yarns, Arville sells ComfortShell fabric that can be used to produce uniforms for firefighters that are both lightweight and comfortable.

 

Check back for more news updates. To book your place at TLC2019, the International Conference on Textile Coating and Laminating, click here.

randomness