Hydrophilic TPE
Dryflex WS are a range of thermoplastic elastomers (TPE), which contain hydrophilic particles. They swell at a controlled rate and percentage when immersed in water. When there is no longer water present the compound shrinks back to its original size, a process of expansion and contraction that can be repeated. The materials have solid structural integrity; unlike many of the equivalent clay based products which can erode over time.
How would you use it?
Dryflex WS+
We’ve further expanded the possibilities with the development of the Dryflex WS+ grades. These materials are designed for applications in high saline environments, such as sea walls, defences and water-stop construction. For example, in 8% saline solution at 23ºC Dryflex WS+ 51446 achieved double the volume swell of Dryflex WS 25E950 after 21 days. Dryflex WS+ 51446 had a volume swell around 300% compared to 150% for Dryflex WS 25E950.
Key Properties
Dryflex WS and WS+ materials are used in applications to form a positive seal and prevent the ingress or exit of water. We have also developed softer grades which offer excellent drapability. They are an ideal choice for water stop applications where the profiles may be coiled or need to be fitted around complex structures.
Compounded in any colour, the water swellable TPE is recyclable in closed loop systems and can be processed using conventional plastic fabricating methods, including extrusion and injection moulding.
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Applications include
- Waterstops
- Water treatment plants
- Tunnels, drains & sewers
- Water tanks
- Seals
Hydrophilic TPE - How does it work?
Fig 1 : The hydrophilic ingredient is compounded into the Dryflex WS TPE at the time of manufacture.
Fig 2 : After immersion in water the Dryflex WS TPE will expand uniformly, at a controlled rate and percentage.
Fig 3 : When there is no longer water present the Dryflex WS TPE shrinks back to its original size.
FAQS
From 350% to 1000% depending on the grade. Other swell rates can be formulated to meet specific application requirements.
It isn’t an ‘instant’ swell, it can take a number of days. Different grades swell at different rates. This is determined by :
- the grade hardness
- the formulated level of swell
- environmental conditions
- profile geometry
- surface finish
Yes, higher temperatures will give a faster swell.
Both acid and alkaline conditions can affect the level of swell.
Increased levels of salinity reduce the level of swell.
Injection moulding & extrusion.
Between 25 to 40 Shore A for our standard grades
The optimal range is 25 to 40 Shore A. It can be possible to go to higher hardnesses but this will affect the swell and processing properties.
No, the material needs to be immersed in the water.
In general the compound is supplied in natural. We can colour compound to a basic palette. Natural compound can be masterbatched, we suggest a masterbatch with a LDPE carrier. Customers often use colour as a function rather than for aesthetics – it can be used to identity different swell rates of the different gradesPLEASE NOTE : The colour changes as the material swells!
Yes, this is one of the strengths of Dryflex WS.
In general 1 tonne
Our Dryflex WS expert
Martin Bradbury
Senior Key Account Manager for HEXPOL TPE Ltd
Downloads
You can also visit our Downloads page for more brochures and information.
