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Identifying plastics

Production and Use

The Tribopen is a simple hand-held device with a snap-on head. It works by measuring the tribo-electric (static) charge generated when its metal or plastic-coated head is brushed over a plastic object. Different plastics have unique molecular structures, so their surfaces generate different static charges. Within a few seconds of the pen's head touching plastic, a red or green LED indicates whether the plastic is in one of two polymer groups. If necessary, the process is then repeated using different heads (or different pens) to test for a narrower group of polymers, until the Tribopen makes a definite identification by a process of elimination.

Unskilled operatives can use the Tribopen, either working with a single pen or several pens for more detailed sorting.

The Tribopen is produced in batches, according to demand. It is made with three shapes of measuring head: pen-type, flat (for flat surfaces like film) and concave (for use on cables).

A single head device can be used to 'stream' unknown materials.




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Practical Action - Technology challenging povertyEuropean Commission - Department for International Development

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