What kind of polymer?

What kind of shape: cylindrical or cubic?

This is done usually by grinding at low temperatures with the help of a cryo-mill. Low temperatures (liquid nitrogen) are required to avoid thermodegradation of the polymers.

Yes. You can put the part in a criogenic liquid. Then grinding. In this way you can obtain powder from the polymer, because the behaviour turn more brittle.

Depending on the size of the final particles you want to obtain there are several options you can follow. In our case we used a cutting mill (e.g., Retsch) to go down to

thank you all :)

Kostyantyn Pivnenko thank you so much :)

Daniel Martinez Krahmer thank you so much for your answer but can you tell me what kind of criogenic liquid i use ? 

ps: PET , PEHD and polystyrène . Are the polymers on which I am working :) 

Liquid nitrogen is commonly used as the cryogenic liquid.  Dry ice (solid CO2) is sometimes used in laboratories.  A lot depends on the scale of your need--small sample prep vs. commercial grinding scale.  There are a wide variety of solutions for different needs.  If the quantity is very small, you may be able to get by without cryo for the polymers you listed.  It also depends on what particle size you want and if uniformity matters. 

You could try a freezer mill. These are manufactured by our company for upto 4g you could use a 6775 instrument follow the link for further information

http://www.spexsampleprep.com/6775freezermill

All polymers have an especific glass transition temperature:

PET = 76°C ; Polyestirene = 100°C and PEHD = -80°C. Under this temperature the behaviour is elastic, then the polymer may be cut in more stifness condition. 

For instance, it will be possible to grinding PET and Polyestirene at room temperature, but PEHD with liquid nitrogen or may be dry ice. 

Also the CryoMill offered by Retsch is very suitable to grind elastic materials to fine powder. Very safe and user convenient, low consumption of liquid nitrogen....

When using the CryoMill or any Mill, you can use the Bead Dispenser to load the wells with the grinding material and even a specific amount of plastic.

http://www.labtie.com/bead-dispenser

https://www.youtube.com/watch?v=OXxi_Lg9MJ4

https://www.youtube.com/watch?v=OXxi_Lg9MJ4

But after cryogenic grinding you get a sharp shape of powder, it will not be round balls.

If you need a specific amount of the powder in a plate, wells or tubes they can customize a "powder" dispenser based on your needs.

https://www.labtie.com/112356-laboratory-powder-dispensers

https://www.youtube.com/watch?v=hxHmImvF3M0

Anyone have an idea about how to grind plastic bag (polyethylene) into powder form? I tried with liquid nitrogen but was not successful? Any suggestion please?

Hello there,

We have several machines to grind various polymers into fine powder. By July'19 we will also install our plant for cryogenic fine grinding of difficult polymers like Nylon (Polyamide), PP, PS, ABS, EVA, PU. Our polymer powders are used for metal coating, interlining fabric coating, masterbatch homogenisation, roto-moulding, etc. You may visit www.rapidcoat.com for more information.

I am trying to grind PET into powder using PET powder grinder and liquid nitrogen. May I know the required liquid nitrogen amount for 20-30 g of PET samples? And, how much time is needed for grinding? Thank you.