Featured Research

from universities, journals, and other organizations

Crash helmet with a useful smell

Date:
October 21, 2010
Source:
Fraunhofer-Gesellschaft
Summary:
Cycle helmets are available in a wide range of types, including foldable models, models fitted with a flashing rear light or featuring an iPhone display. In future, they will start to smell distinctively if they need to be replaced. A new process causes odoriferous oils to exude from plastic materials if they are cracked.

The damaged helmet releases odoriferous substances. Bottom right: the opened microcapsule.
Credit: Copyright Fraunhofer IWM

Cycle helmets are available in a wide range of types, including foldable models, models fitted with a flashing rear light or featuring an iPhone display. In future, they will start to smell distinctively if they need to be replaced. A new process causes odoriferous oils to exude from plastic materials if they are cracked.

Cycling crash helmets have just one purpose: to protect the cyclist's head. But only completely damage-free helmets do the job properly. It is therefore recommendable to buy a new one every now and again, but nobody wants to throw away a perfectly good helmet. It would be better to know for certain that this is really necessary. A new process developed by research scientists at the Fraunhofer Institute for Mechanics of Materials IWM in Freiburg in cooperation with the Fraunhofer Institute for Environmental, Safety and Energy Technology UMSICHT in Oberhausen makes this possible. The polymer materials or plastics produced by the process start to smell if they develop small cracks. Large cracks really cause a stink. The smell comes from odoriferous oils enclosed in microcapsules.

"Cyclists often replace their helmets unnecessarily after dropping them on the ground, because they cannot tell whether they are damaged or not. The capsules eliminate this problem. If cracks form, smelly substances are released," explains Dr.-Ing. Christof Koplin, research scientist at the IWM. The capsules are added to a polypropylene mass which is injection-molded to form the final component. In the case of the bicycle helmet, the microcapsules are inserted in a thick foil made of polypropylene, which is fastened to the head gear.

A layer of melamine formaldehyde resin encloses the capsules so that they are completely airtight and mechanically sealed. It also protects the tiny pods, which are subjected to temperatures of 200 to 300 degrees during injection molding as well as static pressures of up to 100 bar. "Melamine formaldehyde resin proved to be the most suitable encapsulation material in the comparison we conducted of the material systems," explains Koplin. "Inside the capsule there is a porous, hardly deformable silicon oxide core which absorbs the odoriferous substance. This core produced the best results," he adds.

To determine the loads at which the miniscule capsules measuring just 1 to 50 micrometers break open, the scientists test them at the IWM with a Vickers indenter. The engineers calculate the number of capsules required by means of numerical computer simulation. The finished component is then subjected to bending and drawing tests. The tests are only deemed to be successfully completed if the capsules are found to open and exude the odoriferous substances just before the component fails. Koplin: "Our method of detection by smell offers several advantages. It not only indicates when safety-critical polymer components need to be replaced. The exuding smells also enable damage outside the safety range to be detected."

The process is therefore suitable for all products which are difficult to test for defects, such as cycle, motorbike and construction helmets. But it can also be used to check pressure hoses, e.g. in washing machines, which are difficult to access. Smell sensors could also monitor plastic water and gas supply pipes to detect any cracks, because the odoriferous substances emitted are noticeable over long distances. "Smell detection is already in use for coated metal components. We are applying the process for the first time to polymer materials. The cycle helmet is being used as a demonstrator. Work on the capsules has finished and we are now completing characterizing tests on individual configurations," states Koplin.


Story Source:

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


Cite This Page:

Fraunhofer-Gesellschaft. "Crash helmet with a useful smell." ScienceDaily. ScienceDaily, 21 October 2010. <www.sciencedaily.com/releases/2010/06/100607112046.htm>.
Fraunhofer-Gesellschaft. (2010, October 21). Crash helmet with a useful smell. ScienceDaily. Retrieved July 22, 2014 from www.sciencedaily.com/releases/2010/06/100607112046.htm
Fraunhofer-Gesellschaft. "Crash helmet with a useful smell." ScienceDaily. www.sciencedaily.com/releases/2010/06/100607112046.htm (accessed July 22, 2014).

Share This




More Matter & Energy News

Tuesday, July 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Government Approves East Coast Oil Exploration

Government Approves East Coast Oil Exploration

AP (July 18, 2014) The Obama administration approved the use of sonic cannons to discover deposits under the ocean floor by shooting sound waves 100 times louder than a jet engine through waters shared by endangered whales and turtles. (July 18) Video provided by AP
Powered by NewsLook.com
Sunken German U-Boat Clearly Visible For First Time

Sunken German U-Boat Clearly Visible For First Time

Newsy (July 18, 2014) The wreckage of the German submarine U-166 has become clearly visible for the first time since it was discovered in 2001. Video provided by Newsy
Powered by NewsLook.com
Obama: U.S. Must Have "smartest Airports, Best Power Grid"

Obama: U.S. Must Have "smartest Airports, Best Power Grid"

Reuters - US Online Video (July 17, 2014) President Barak Obama stopped by at a lunch counter in Delaware before making remarks about boosting the nation's infrastructure. Mana Rabiee reports. Video provided by Reuters
Powered by NewsLook.com
Crude Oil Prices Bounce Back After Falling Below $100 a Barrel

Crude Oil Prices Bounce Back After Falling Below $100 a Barrel

TheStreet (July 16, 2014) Oil Futures are bouncing back after tumbling below $100 a barrel for the first time since May yesterday. Jeff Grossman is the president of BRG Brokerage and trades at the NYMEX. Grossman tells TheStreet the Middle East is always a concern for oil traders. Oil prices were pushed down in recent weeks on Libya increasing its production. Supply disruptions in Iraq fading also contributed to prices falling. News from China's economic front showing a growth for the second quarter also calmed fears on its slowdown. Jeff Grossman talks to TheStreet's Susannah Lee on this and more on the Energy Department's Energy Information Administration (EIA) report. Video provided by TheStreet
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