What about thermal treatment and toxicity

Dear all,

a friend, chemist as myself, talked me about this amazing project.
My main concern is about the toxicity of substances used or produced during the recycling process (water for cleaning and smokes during the heating and compression) as well as the possible toxicity of the final producs, that maybe will be used as food container (rain water?) or others.

If this topics have not been explored yet, maybe others scientists in this forum and myself can produce a document assessing the toxicity of the recycled plastics produced.

Thanks you all again for sharing this great idea

Gian Giacomo Asara



I’m very interested in this information. Did you ever put anything together? Or did you find any information elsewhere?


Hi all! I’m also struggling with the safety of melting plastics.I did quite some research: talked to plastic recycling companies, companies that sell gass masks, design studios that melt plastics themselves and give workshops, experts of polymers.
I’m still not 100% sure about the safety but I can tell you what I have discovered so far. I put the sources of information between brackets which you can find at the end of this document.
There are different types of plastics (as Dave explained). In the types PET (#1), PVC (#3) and PS(#6) acids are processed and harmful fumes are released during heating (Schoemaker, 2015). According to Jansen (2016), Polyethylene and Polypropylene can be seen as refined wax and are not dangerous to melt.So be aware of the type of your piece of plastic!
Melting temperature
Important is to stay under a certain temperature when heating the plastic, since the material only needs to be melted and not burned. When burning plastic, soot is released which is harmful. When keeping temperatures below the injection molding temperature of the material, it is safe to heat the material (Jansen, 2016). It is important to use equipment for heating with a constant temperature, so that the chance of burning is small. If you are experimenting with the plastic I suggest you use a gass mask since you have no total control over the process.
I still don’t feel comfortable about melting the plastic. A bad smell is released and I feel like there is not much research done yet into the toxicity of heating plastic.
If you can help me out, let me know!!
– Cities Foundation. (2015). Reward System. Retrieved on 27 March, 2016 from http://www.wastedlab.nl/en/rewards/
– Jansen, K.M.B.(Professor of Emerging Materials, Faculty of Industrial Design, Section Product Engineering of department of Design Engineering, Delft University of Technology). (2016). Retrieved on 10 February, 2016 from during a talk.
– Schoemaker,H. (Sales and Trading Manager Plastics at SITA). (2015) Retrieved on 11 December, 2015 during phonecall.
-Van Oossanen, M. (Technical support Applied Labs, Faculty of Industrial Design Engineering, TU Delft). (2016). Retrieved on 29 February 2016 from email.

I have done a little bit of investigation into toxicity, which when looking at the 7 basic types, the only concerns would be with Type 1 (PETE), Type 3 (PVC), and Type 6 (PS). Reason being is all of these have the carcinogens (Phthalates, Polyvinyl chloride is considered carcinogenic when gaseous, and Styrene of course in type 6 is considered carcinogenic on the molecular level) That being said, As long as these are not burned(keep good temperature control) they should be relatively safe. as well for food applications, any products made should not be heated for obvious reasons. Mitigate risk as best as possible and where applicable.