'There's a hole in my bucket ...'

April 25, 2005
Holger Wack inspects samples of his new plastics in dry and swollen condition

Cracks, splits and holes are by definition one of the biggest problems in sealing technology. A new addition has recently been made to the thermoplastic elastomer family: Swellable variants of these plastics react to leaking water and thus stop the leaks.
Everyone is familiar with thermoplastic elastomers (TPE) used in toothbrushes, cellphone keypads or screwdrivers. They benefit ordinary users, giving the hand a pleasantly soft and secure grip. They also benefit manufacturers, who can melt down the rubbery plastics and process them in the same way as the thermoplastics polyethylene, polypropylene and polystyrene. The TPE material can also be injection-molded, extruded or calandered (rolled into sheets and films) in large quantities at correspondingly low costs. It can even be welded, which is particularly desirable when using it in the building industry.

Image: Holger Wack inspects samples of his new plastics in dry and swollen condition.

Researchers from the Fraunhofer Institute for Environmental, Safety and Energy Technology UMSICHT have succeeded in extending this family of materials by adding a further component: polyacrylate which is known for its excellent absorptive properties. The resulting thermoplastic-elastomer composites are registered as Q-TE-C®. They swell up to several times their dry volume when in contact with water. But what is even more important: they can be processed like TPE. “We have moved into new territory,” Holger Wack firmly believes after extensive research in patent publications. “That encouraged us to apply for a patent on the basic formulation just under a year ago.”

The deputy head of the special materials department already has a laundry list of potential applications, mostly dealing with the broad topic of sealing technology. These plastics could reveal their talents whenever it is important to prevent water or aqueous solutions from leaking out or penetrating into adjacent spaces. Wack explains a self-sealing pond liner as an illustration of how they work. “It consists of a layer of the new material with normal waterproof sheeting on both sides. If water seeps out through a tiny hole, the Q-TE-C® layer swells up and seals the damaged spot.” In pipe connections, another significant factor comes into play: The damp material is now locked between solid parts, which restricts its volume expansion. The sealant increases the pressure on the solid parts and thus mends the leak.

The various types of plastic require different specific properties depending on their application. The researchers are therefore currently elaborating methods for demonstrating that a particular material is suitable for the sealing task it is designed to do. Details of this and other aspects will be shown in Hall B2 at IFAT, the leading international trade fair for waste disposal and the environment, held in Munich, Germany from April 25 to 29.

Source: Fraunhofer-Gesellschaft

Explore further: Scientists find electrifying solution to sticky problem

Related Stories

Scientists find electrifying solution to sticky problem

August 25, 2015

Inspired by the limitations of biomimetic glues in wet environments, scientists from Nanyang Technological University, Singapore (NTU Singapore) have invented a glue that will harden when a voltage is applied to it. This ...

Scientists grow high-quality graphene from tea tree extract

August 21, 2015

(Phys.org)—Graphene has been grown from materials as diverse as plastic, cockroaches, Girl Scout cookies, and dog feces, and can theoretically be grown from any carbon source. However, scientists are still looking for a ...

What flows on Pluto?

August 20, 2015

It's now been over a month since the New Horizons spacecraft flew by one of the last unknown outposts of our solar system and although we've only just seen a trickle of the data it collected, it has all been rather exciting. ...

Oceanic junk ranges from Legos to suspected jet wreckage

August 14, 2015

For years along the Cornish coast of Britain, Atlantic Ocean currents have carried thousands of Lego pieces onto the beaches. In Kenya, cheap flip-flop sandals are churned relentlessly in the Indian Ocean surf, until finally ...

Recommended for you

New nanomaterial maintains conductivity in 3-D

September 4, 2015

An international team of scientists has developed what may be the first one-step process for making seamless carbon-based nanomaterials that possess superior thermal, electrical and mechanical properties in three dimensions.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.