Polyethylene (PE)

With the first test, we wanted to testify if sample can be ground without problems, using a sieve ring of 0,5 mm trapezoidal perforation.

For this, about 15 g of sample have been ground within 90 seconds. Sieve ring and rotor use to be mostly free of residues, a grinding of higher amounts (up to 40-50 g per batch) should be possible with the standard collecting pan.

For a grinding of higher amounts (100 g as desired), we recommend using the accessories for grinding large quantities or the optional sample exhauster system with cyclone separator.

Because a bit of sample use to stick to the collecting pan by electrostatic charge, we recommend cleaning the equipment by vacuuming with a soft brush.

Even with slow feeding rate, sample started to stick to rotor and sieve ring after 2:20 minutes. We are guessing that electrostatic charged, fine ground sample might stick to the sieve ring and rotor, became warm and started to melt by friction.

So after 8 g of sample have been fed, grinding sound indicated that a bit of sample might start sticking and melting. We interrupted the grinding process.

In our last test, we wanted to testify how many sample can be ground per batch when the plastic has been embrittled in liquid nitrogen previously.

For this, we placed 50 g of sample into a plastic bowl and poured out liquid nitrogen into the bowl until all sample has been covered with nitrogen and has been chilled.

Afterwards, only 3-4 pieces of plastic have been taken out with a spatula and have been fed to the feeding funnel. That procedure has been repeated until the grinding sound indicated that sample starts to stick.

After a total grinding time of 5 minutes, just 20 g of sample have been fed. No higher amounts can be ground. Sample started to melt in front of the rotors ribs and at the sieve ring.

We used a 1,0 mm sieve ring for pre grinding of sample. Afterwards, we took out the sample and embrittle it by placing into liquid nitrogen.

Afterwards, we ground the sample with 0,25 mm sieve ring by a spoon wise slow feed rate. After 7:30 minutes, all sample has been ground. A bit of sample got lost because it was jumping out of the feeding funnel or our box with nitrogen which has been hold next to the feeding funnel.

About 6,9 g of sample got brushed out of the collecting pan. A higher amount of sample is sticking to the collecting pan by electrostatic charge.

Sieve ring and rotor use to remain free of residues, a grinding of higher amounts is possible.