Yulex believes a desire for options other than petrochemical-based raw materials will create opportunities in the footwear sector and its repositioning in Asia will help it capitalise on demand.

The team at Yulex has been busy. The natural rubber specialist has revamped its foam offering for wetsuits – resulting in Decathlon launching the first 100% natural rubber polymer wetsuit suit last summer  – and launched a textile filament of its purified natural rubber latex targeted at the stretch denim market and socks. But it also has its eye on the footwear sector, believing that, as part of sustainability commitments, brands are seeking to move away from petrochemical-based products and are looking for natural alternatives with traceable supply chains. 

The company has its roots in US-based Yulex Corporation, which spent years developing natural rubbers from guayule shrubs in Arizona, aiming to establish a domestic supply chain. Founder Jeff Martin and his colleagues worked with outdoor brand Patagonia on an alternative to neoprene, and the companies launched guayule rubber-containing wetsuits in 2013. 

Over the years, the company segued from guayule, with that technology commercialised by Bridgestone and Versalis, changing its raw material to latex extracted from rubber trees, Hevea, sourced from plantations in Sri Lanka and Guatemala. However, with most of the natural rubber producers located in Thailand and Vietnam, for Mr Martin and now-CEO Liz Bui – who was born in Vietnam but moved to the US as a child after the war – that meant a relocation. “In terms of carbon footprint, it didn’t make sense to move a large container to Southeast Asia,” Ms Bui tells us. “Most of the footwear companies have a huge presence in Vietnam and there's a lot of apparel moving there, too, so we wanted to develop a natural rubber supply chain closer to production. It just made sense to start thinking about how we can really help our customers, and transport is a huge part of any carbon reduction strategy.” 

Certification process

Although smallholder farms provide 90% of the rubber in Thailand and about half in Vietnam, many were operating independently, so Mr Martin and Ms Bui partnered the Programme for the Endorsement of Forest Certification, Forest Trends Association, Vietnamese Academy of Forest Science, Vietnam Forest Certification Office and the Vietnamese Rubber Association, working collaboratively to make introductions and galvanise the smallholders. “Together, we travelled all over Vietnam, talking to smallholders talking about sustainability and finding cooperatives and legal business entities to coordinate the sustainable forest practices and certification, so they could sell their rubber to processors.” 

Yulex now works with more than 240 smallholders in Thailand and 1,500 in Vietnam. Each has registered land-use rights, dates of first tree plantings going back as far as 1940 in Thailand and 1994 in Vietnam, and geolocation coordinates of the plantation, through their smallholder cooperative. This means they will be compliant with the incoming EU Deforestation Regulation (EUDR), which requests proof that products do not contribute to deforestation or forest degradation. “For these smallholders, their livelihood and their household income is derived from their small plot of land,  which is anywhere from 1 to 1.5 hectares, in their backyard,” adds Ms Bui. “After some 100 years of the natural rubber industry, this is still a cash business, yet you have groups who don't really have good access to banking or to credit. And as you move up the supply chain, it is the retail brands that make the largest margin and the person on the ground supplying the raw material that makes the least.” To help address this imbalance, Yulex set up an Equitable Agriculture profit-share programme to provide better security of income for the farmers. 

Protein removal 

Tree latex consists of an emulsion of water and rubber (or biopolymers) and non-rubber particles. The non-rubber particles consist of dirt, oil, proteins, metals and other impurities, which are removed. Removing the proteins also substantially removes the risk of Type 1 latex allergy responses. The purified latex is branded as Yulex Pure, and is used to make Yulastic filament and, in some instances, the foams. The change of supply chain also allowed the company to work with different producers and manufacturers, increasing the research and development to create upgraded products, which it launched last summer. 

The foams are versatile; they can be made with various properties depending on the end product. Alongside the wetsuits, they have found a home in bags, accessories and boots. Nutrition brand Sports Research last summer launched what it claims is the first natural rubber waist trainer while, earlier in the year, Scottish inland ‘surf resort’ Lost Shore announced all its wetsuits would be made from Yulex foam after their tests showed they were warmer than standard synthetic rubber suits. “Natural rubber is a very good polymer – consider that aeroplanes have to use 100% natural rubber for their tyres,” comments Ms Bui on its attributes. “It is really about performance first for us, but it also has a good sustainability story – that is a bonus.”

Footwear focus

There are clearly multiple factors affecting the choice of materials, including cost, ease of use, sustainability credentials and how they fit into existing manufacturing and supply chains. The price of both natural and synthetic rubbers fluctuates depending on supply and demand: natural rubber depends on crop yields among other things, while synthetic alternatives’ prices are based on petroleum values. Although it might take a long time, natural rubber biodegrades, depending on the level of vulcanisation or how much curing agent is in the product, whereas synthetics will not; there is already a big carbon reduction from choosing a natural product over one made from a non-renewable resource and the emissions associated with its extraction and manufacture, suggests Ms Bui. 

As well as growing the filament business for socks and denim, the company is now focusing on increasing its footprint in the footwear industry. The foam material’s adaptability means it can be used for outsoles and insoles, as well as the foam in the collar and the tongue.

Early adopters for the Yulex foam include US brand Bogs Boots, UK-based Little Green Radicals and sailing shoe brand Equipement De Vie. At the December edition of ISPO Munich, Ortholite Cirql presented a ‘Zero’ concept shoe which had Yulex foam uppers (shoe tongue) as well as Yulex natural rubber outsoles. Brand partners in Vietnam are also helping to test the various formulas and performance attributes of Yulex products and materials in foams, outsoles and filament for knitted uppers.

“Footwear always used to be about natural rubber, but the industry has converted almost entirely to synthetic materials because they are cheaper and easier to work with; there's an exact chemistry, whereas with natural rubber there’s a lot of knowhow and expertise that's been lost, so we're trying to bring that back,” says Ms Bui. “But I think with the advent of sustainability, and the need to reduce carbon emissions, brands are wanting to try to move back to using natural products. What's going to be important is which brands adopt it first.” 

Yulex partner French brand Equipement De Vie was founded to address the need for shoes that meet sailors’ rigorous demands.
CREDIT: Equipement De Vie

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