I am working with pyrolysis of plastic mixtures and after the condenser outlet, I am using two liquid traps, one with water and one with 0.1 M NaOH for trapping some of the non-condensable gasses. I am using PP as the main material and adding PET and PA 6 in lower amounts. Almost all of the NaOH traps started to turn yellow/orange over time (except the runs that contained pure Polypropylene) and I am not sure what could have caused it. The color of the water traps remains unchanged. My idea was that it could have something to do with some of the trapped carbon dioxide but once again, those are just guesses. Anyone has any idea? Any help is appreciated.
I have also attached a figure, where on the left, you can see unaltered NaOH trap from a polypropylene run, the remaining two flasks are the NaOH traps after runs with 10 wt% PET and 10% PA 6.
Not my field, but might you have trapped phenolic compounds in the base and they have polymerised?
I would follow the explanation proposed by Paul Milham. PP is the aliphatic polymer, basically saturated and having no polar or aromatic functional groups. Apparently, not so much of decomposed water-soluble material (or that dissolved in sodium hydroxide) was produced during pyrolysis. Anyway, adding PET ( polyethylene terephthalate) and PA (polyamide? aromatic one?) provides a source of aromatic and/or functionalized material which, during pyrolysis may produce acidic products trapped effectively by sodium hydroxide and capable of condensation reactions.
My answer would be based on theory of colour and constitution.
Yellow colour means formation of a compound which is absorbong a longer wavelength of visible light.
This means that if we are using polymers with unsaturation in side chains… there is a possibility of colour change in traps.
My answer would be based on theory of colour and constitution.
Yellow colour means formation of a compound which is absorbong a longer wavelength of visible light.
This means that if we are using polymers with unsaturation in side chains… there is a possibility of colour change in traps.
My answer would be based on theory of colour and constitution.
Yellow colour means formation of a compound which is absorbong a longer wavelength of visible light.
This means that if we are using polymers with unsaturation in side chains… there is a possibility of colour change in traps.
This means that if we are using polymers with unsaturation in side chains… there is a possibility of colour change in traps.