Plastics identification through burning (with odor and flame table)

I don't know how I could forget, during all these years that I keep this website, talking about something as important as the identification of plastics through burning. This is a very common process in recycling companies and aims to identify, for prior separation, the different types of polymers present in a shipment.

The process has no secret, a candle and / or a lighter, tweezers or pliers, are the necessary tools to perform this work. Depending on the type of plastic, a different effect occurs when the flame comes into contact: yellow flame, blue flame, soot release, flame self-extinguishing, etc. In addition, the smoke from burning has a particular odor for each polymeric family, through which, the most experienced recyclers, can even distinguish between the members of that family (eg: polyamide family - members: polyamide 6, polyamide 6.6 etc).

There has been a table circulating on the internet since the early 2000s that shows these burning characteristics, the problem is that it has a series of errors (eg, saying that polyacetal has a styrene monomer odor). In 2004, Hélio Wiebeck and Ana Magda Piva used this table in the book "Reciclagem de Plásticos" (Plastic Recycling), correcting some errors and keeping a few others.

I reformulated the table and added illustrations (just for visual reference), the result is this:

Polymers		Burning test behavior	Smoke odor	Burning illustration
	(L)LDPE, MDPE, HDPE	Blue flame with yellow apex. Drips like a candle	Paraffin
	PP	Blue flame with yellow apex. Drips like a candle	Paraffin but a little tastier than PE
	PMMA	Blue flame with yellow apex. Bubbles in the piece, burns slowly, and does not carbonize	Garlic
	PVC	Yellow flame with green vertex. Self-extinguishing flame	Chlorine
	ABS	Yellow flame. It carbonizes and produces smoke with a lot of soot. Burns a little more slowly than PS and SAN	Burnt rubber and styrene monomer*
	PS	Yellow flame. Carbonizes and produces smoke with a lot of soot	Styrene monomer*
	SAN	Yellow flame with glow. Produces sooty smoke and carbonizes more than PS	Styrene monomer*
	PC	Hard to burn, self-extinguishing yellow flame, carbonizes and produces soot	"Medicine" (imagine the smell of a concentrated pharmacy)
	PET	Yellow flame. Produces a little black smoke	Characteristic. Use the odor of a burnt bottle as a reference
	POM	Low, round blue flame, almost invisible, without soot	Extremely strong odor to the point of causing a momentary headache if the smoke is breathed in deeply
	PU	Produces a lot of smoke	Characteristic. Use as a reference the odor of burnt mattress foam
	PA (all)	Blue flame with yellow apex. It takes time to catch fire, does not generate soot and drips if you keep the fire for a long time	Burnt hair
	Cellulose acetate	Yellow flame. Ignites	Acetic acid
	Cellulose butyrate acetate	Blue flame with sparks. Ignites	Rancid butter
	PTFE	Does not catch fire, chars	As it does not burn, it does not emit odor

* this monomer, when liquid, smells like a thinner, but when polymerized and burned it has a smoother and sweeter odor

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