Drying[edit | edit source]
PET needs to be dried prior to extrusion in a Recyclebot as otherwise it will undergo rapid hyrdolyzation at high temperatures, and reduce the molecular mass. In addition, other polymers may absorb moisture from the environment and need to be dried prior to extrusion.
Drying: Equipment[edit | edit source]
- Convection Drying Oven (Any oven will generally work, ovens at home run off the same convection principles of heating and moving air. If using a home oven, be careful of temperatures, and be aware that there could potentially be burning plastic inside of it, if proper precautions are not taken)
- Drying tray (Any metal tray to hold the PET shreds)
- Elevation tray (Any metal tray to put under drying tray)
MOST specific equipment[edit | edit source]
- Contact: Jerry Anzalone
- Pressure Range: Ambient to -100 kPa.g.
Drying: Procedure[edit | edit source]
- Turn on the oven
- Evenly distribute the plastic in the drying tray. This exposes more surface area to enhance evaporation speed.
- Open the oven door.
- Place pan elevator first in VWR chamber
- Place the drying tray inside the oven on top of the elevation tray
- Place thermometer inside facing toward you.
- Close the oven door.
- Close the vent (Rotate counterclockwise)
- Activate VWR (Bottom Left on switch)
- Set the temperature on VMR to 2 on the dial (35 degrees Celsius)
- Note: cycle duration light shuts off when oven has reached the designated temperature
- Activate vacuum pump
- Note: oil level on pump should be adequate
- Leave polymer inside for 2 hours.
- Note: Monitor Oven temperature. It should be around 35 degrees celsius
- Switch off the oven and open the vent (counterclockwise) before carefully opening the door and letting it cool for a few minutes.
- Quickly place the polymer in an airtight container, such as inside two (2) layers of plastic bags that are twisted and tied shut. As long as the polymer is not allowed to reabsorb much water from the air, any arrangement will work.
- Store plastic in a cool dry place until it is to be used. One excellent method is to place the dry polymer inside a bag, which also has dessicant. This will help to remove any moisture that may have accrued whilst handling it.