Polyester (18-18)

Plastics could be ground by shearing forces. Instead of a standard cutting mill (with up to ~ 3000 rpm), our Variable Speed Rotor Mill PULVERISETTE 14 premium line can be converted into a cutting mill with up to 18.000 rpm.

Plenty of samples can be ground with our Variable Speed Rotor Mill PULVERISETTE 14 premium line, down to < 0,5 mm. Some samples achieve a fineness < 0,2 mm, too.

With our first trial, we ground the sample < 1 mm fine to give a wide spread distribution of particles, as desired. If the start size of sample would be larger, this type of grinding can also be performed as a pre-grinding step.

For the desired amount of sample, we used the Small Volume Cyclone (passive, without vacuuming). The complete sample was fed and ground within 30 seconds. The grinding sound was typical and vanished instantly after the last fragment of sample was fed.

We found 2 grams of sample material inside the collecting Bessel and about 0,3 grams of fine dust on the grinding chamber lid. Those samples were brushed off and merged with the 9,5 grams of sample. A bit of sample stuck in front of the static knives of the sieve shell holder. A lot of fine ground, electrostatic charged sample could not be brushed off.

With the second test, we used sieve shells of 0,2 mm for grinding. Also with this trial, we fed the original start size material without a previous precutting.

It took only 70 seconds until the complete sample was fed and ground. The sound of grinding was typical. Now the majority of ground sample remained inside the grinding chamber and was not transferred into the cyclones attached collecting glass.

The sieve shells were not significantly clogged. Even below the rotor, no significant amount of sample was left.

Surely even higher amounts of sample could be ground this way, too. We brushed off: 1 gram of sample from the lid; 6,7 grams from the collecting vessel and about 4,5 grams from the cyclones attached collecting glass.

Like in result one, a lot of very fine electrostatic charged sample could not be brushed off.

Intensive cleaning was performed with warm, soapy water. Afterwards, the equipment was flushed with fresh water.