London, June 8 (IANS) Scientists are designing a crash helmet to stink if it develops a defect, so that you can replace it with a safer one.
A new process developed by scientists at the Fraunhofer Institute for Mechanics of Materials IWM in Freiburg makes this possible.
The smell comes from smelly oils enclosed in micro-capsules. Cyclists often replace their helmets unnecessarily after dropping them on the ground, because they are unsure about its safety status.
The capsules eliminate this problem. If cracks form, smelly substances are released, explains Christof Koplin, research scientist at the IWM.
The capsules are added to a polypropylene mass which is injection-moulded 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 moulding as well as static pressures of up to 100 bar, says an IWM release.
‘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.
