By combining two well-established materials – Outlast phase-change material and the super absorbent fibre Oasis SAF – Charlton Lamb, based in London, UK, appears to have come up trumps with a solution to produce caps, helmets and clothing that limits heating up of the body and sweating.

These garments could be worn when playing sports or in hot and unpredictable environments.

As a non-scientist, it was shear curiosity and frustration as a cricketer that drove Lamb to develop the concept that has become a real business opportunity.

‘It started with me wanting to stop cricket helmets from making your head sweat profusely – they are dreadful things to wear,’ explains Lamb. ‘I knew of these two fabrics. It was a whim to put the materials together.’

Outlast is a phase-change material originally developed for NASA in 1988 by Triangle Research and Development Corporation, USA. Microencapsulated phase change ‘thermocules’, which contain different paraffins, are embedded in an acrylic compound binder shell to interact with the body and prevent excessive temperature variations. They absorb, store and release heat as they change from a solid to liquid and vice versa.

Oasis is a polyacrylate-based super-absorbent fibre, manufactured by Technical Absorbents Ltd based in Grimsby, UK. With high rates of saline and water uptake in a matter of seconds, the material has already been employed in a range of applications that include food packaging, and medical and dental fabrics.

‘The theory is that the phase change material must have an optimum level at which it can absorb heat. If you surpass that, you may start to sweat – but as soon as you sweat, the absorbant soaks it up. There must be a continuous heat exchange [between the two materials],’ says Lamb.

‘Initially we made caps by layering one fabric onto another. My son was playing a cricket match against people from the Marks & Clerk European trademark company, and was wearing one of these caps. They asked about it and suggested we patented the combination of the two materials in applications from head to foot.’

That was last summer and since the idea has taken off. Lamb is in negotiations with a major American manufacturer of baseball caps for teams and fans. ‘[It] is about getting the manufacturing right,’ explains Lamb. A knitted cotton carrier sandwiches the two fabrics, with all three layers heat bonded together. ‘We wanted to get the cap weight as close as possible to the weight of the existing one [but with the extra carrier] by re-engineering the materials to reduce the weight.’

Lamb is also in talks with a technical textiles specialist in the UK to explore knitting yarns of the two materials together, rather than layering, for a stronger ‘interface between the two at all times’.

He adds, ‘[You can also] up the treatment of both the Outlast and the absorbency effect. So you can experiment nearly non-stop to get the optimum combination depending on what the end product is’.

Technical Absorbents’ Business Development Manager Dave Hill exhibited the caps at the INDEX textile show in Geneva, Switzerland, from 15-18 April, and received interest from several potential end users. These include garments to be worn under body armour by police officers and the military. Lamb is also looking to supply medical in-soles to the UK’s National Health Service to inhibit swelling of patients’ feet.

Hill says, ‘We would like to supply the overall cooling technology across various final applications. We have pursued solutions which were based on wetting [Oasis], so it would evaporate and have a cooling effect. This is a different take on it. Our material is acting as a sweat absorbent with a phase change material that provides the cooling effect. We do not have to pre-wet it’.

The next stage is scientific analysis and validation. Hill adds, ‘If you look at other technologies on the market, there are gel packs that have been pre-wet. But our material is fibrous, allowing you to incorporate it into garments. We are conducting further R&D on combining it with a phase change material to see how much it cools and how much sweat it can absorb, to quantify performance to better cost it and add value for a greater market push’.

Further information:

Outlast
Technical Absorbents