Featured Research

from universities, journals, and other organizations

Using nature as a model for low-friction bearings

Date:
May 14, 2014
Source:
Forschungszentrum Juelich
Summary:
The mechanical properties of natural joints are considered unrivalled. Cartilage is coated with a special polymer layer allowing joints to move virtually friction-free, even under high pressure. Using simulations on supercomputers, scientists have developed a new process that technologically imitates biological lubrication and even improves it using two different types of polymers.

The mechanical properties of natural joints are considered unrivaled. Cartilage is coated with a special polymer layer allowing joints to move virtually friction-free, even under high pressure. Using simulations on Jülich's supercomputers, scientists from Forschungszentrum Jülich and the University of Twente have developed a new process that technologically imitates biological lubrication and even improves it using two different types of polymers. The results will be published in the science journal Nature Communications.

Lubricants are required wherever moving parts come together. They prevent direct contact between solid elements and ensure that gears, bearings, and valves work as smoothly as possible. Depending on the application, the ideal lubricant must meet conflicting requirements. On the one hand, it should be as thin as possible because this reduces friction. On the other hand, it should be viscous enough that the lubricant stays in the contact gap. In practice, grease and oils are often used because their viscosity increases with pressure.

Biological lubrication in contrast is much more efficient. In joints, a thin, watery solution prevents friction. The thin film stays where it should thanks to a trick of nature. A polymer layer is anchored to the cartilage at the end of bones. Polymers are a string of densely packed, long-chain molecules. They protrude from the cartilage and form "polymer brushes" which attract the extremely fluid lubricant and keep it in place at the contact point.

Over the last 20 years, numerous attempts have been made to imitate the natural model technically. But with no resounding success. The tentacle-like polymers on surfaces opposite each other tend to get tangled up in each other. They slow each other down and detach from the surfaces. In technical systems, individual polymers that become detached are difficult to replace as they do not possess the same self-healing mechanisms as in a natural organism.

Jülich physicist Prof. Martin Müser came up with the idea of using two different polymers at the contact point to prevent the polymers becoming entangled. "Using supercomputers, we simulated what would happen if we applied water-soluble polymers to one side and water-repellent polymers to the other side," says head of the NIC (John von Neumann Institute for Computing) group Computational Materials Physics at the Jülich Supercomputing Centre (JSC)." This combination of water-based and oil-based liquids as a lubricant reduced the friction by two orders of magnitude -- around a factor of 90 -- compared to a system comprising just one type of polymer."

Measurements with an atomic force microscope at the University of Twente in the Netherlands verified the results. "The two different phases of the liquid separate because they repel each other. This simultaneously holds the polymers back and prevents them from protruding beyond the borders," says Dr. Sissi de Beer, who recently moved from Müser's group to the University of Twente.

The low-friction two-component lubricant is interesting for numerous applications. One example are simple piston systems, like syringes, which are used to precisely administer even tiny amounts of a drug. Above all, the new process could provide low-friction solutions where high pressures and forces occur locally -- for example, axle bearings and hinges. For the most common lubricant -- engine oil -- an alternative has yet to be found; conventional polymer brushes are unable to withstand the high temperatures.


Story Source:

The above story is based on materials provided by Forschungszentrum Juelich. Note: Materials may be edited for content and length.


Journal Reference:

  1. Sissi de Beer, Edit Kutnyanszky, Peter M. Schön, G. Julius Vancso, Martin H. Müser. Solvent-induced immiscibility of polymer brushes eliminates dissipation channels. Nature Communications, 2014; 5 DOI: 10.1038/ncomms4781

Cite This Page:

Forschungszentrum Juelich. "Using nature as a model for low-friction bearings." ScienceDaily. ScienceDaily, 14 May 2014. <www.sciencedaily.com/releases/2014/05/140514084503.htm>.
Forschungszentrum Juelich. (2014, May 14). Using nature as a model for low-friction bearings. ScienceDaily. Retrieved September 2, 2014 from www.sciencedaily.com/releases/2014/05/140514084503.htm
Forschungszentrum Juelich. "Using nature as a model for low-friction bearings." ScienceDaily. www.sciencedaily.com/releases/2014/05/140514084503.htm (accessed September 2, 2014).

Share This




More Matter & Energy News

Tuesday, September 2, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Halliburton Reaches $1B Gulf Spill Settlement

Halliburton Reaches $1B Gulf Spill Settlement

AP (Sep. 2, 2014) — Halliburton's agreement to pay more than $1 billion to settle numerous claims involving the 2010 BP oil spill could be a way to diminish years of costly litigation. A federal judge still has to approve the settlement. (Sept. 2) Video provided by AP
Powered by NewsLook.com
Google Teases India Event, Possible Android One Reveal

Google Teases India Event, Possible Android One Reveal

Newsy (Sep. 1, 2014) — Google has announced a Sept. 15 event in India during which they're expected to reveal their Android One phones. Video provided by Newsy
Powered by NewsLook.com
Australian Airlines Relax Phone Ban Too

Australian Airlines Relax Phone Ban Too

Reuters - Business Video Online (Aug. 26, 2014) — Qantas and Virgin say passengers can use their smartphones and tablets throughout flights after a regulator relaxed a ban on electronic devices during take-off and landing. As Hayley Platt reports the move comes as the two domestic rivals are expected to post annual net losses later this week. Video provided by Reuters
Powered by NewsLook.com
Hurricane Marie Brings Big Waves to California Coast

Hurricane Marie Brings Big Waves to California Coast

Reuters - US Online Video (Aug. 26, 2014) — Huge waves generated by Hurricane Marie hit the Southern California coast. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins