Slashdot Mirror
World's First Practical Plastic Magnet
Stopmotioncleaverman writes "New Scientist is reporting that scientists at the University of Durham in the UK have created the world's first plastic magnet to work at room temperature from two compounds, emeraldine base polyaniline (PANi) and tetracyanoquinodimethane (TCNQ). In 2001, scientists in Nebraska created a plastic magnet, but it only worked at 10 Kelvin.
Most notably from the article - "One of the most likely applications is in the magnetic coating of computer hard discs, which could lead to a new generation of high-capacity discs".
This story is also being reported in lots of other places."
This is only their first prototype. The fact that it took some time for the magnetic properties to exhibit themselves may be a property of the polymer or it could simply be a result of what amounts to guesswork in producing the stuff in the first place.
Now that they know they can get magnetic properties from the polymer they can work on refining it - making it stronger, more uniform and possibly "faster".
Also, there's no real detail about the methods behind the creation of the magnets - for all you know it might cost them 50p to make each magnet, which would make mass-produced children's toys perfectly possible.
What makes a speaker good is it's mainly the cone itself: it has to be very rigid but also very thin; if it's too heavy the amplifier needs to be more powerful (which reduces it's efficiency), and if it's too elastic it will vibrate and bend when moved back and forth, creating a nasty distortion. Not only that, the cone material has to be sonically "dead" (won't resonate at audible frequencies).
Paper is the preffered choice; there's also kevlar laminate for some high end speakers. Some high frequency speakers ("tweeters") are made of aluminium.
In fact, one of the latest "advancements" in speaker construction was not long ago when a japanese fella discovered how to shape thin wood sheets into cones... after soaking them with sake - apparently it's good for more than drinking, and makes one hell of a cone material. Not cheap though.
I build my audio gear, and you wouldn't beleive the ammount of variables that goes into speaker designing (number of speakers, enclosure volume and shape, variable impedances, type and implementation of crossover network, etc). I think this technology could improve the magnets used in speakers if nothing else, making them cheaper, or stronger, but plastic cones (unless VERY rigid), it's not a good idea overall.