Blown Polyethylene Vapours

Possibly the product could come from reaction between the methylene units and oxygen or nitrogen in the air: when you loose your bubble, that is most likely because a burn or excessive combustion occured at some point of the film, possibly signalling a reaction, which couldonly occur with the oxygen or nitrogen in the air.

If the gas smells pungent, then the simple rule of safety is that it is bad for you.

Just a suggestion Poison,

Take a gas sample and have it tested.

What are the chemical and processing differences between resin and reprocessed resin? How might these differences produce the stronger pungent odour.

Brad

I agree. I would suspect the pungent odor may come from the release of either incompletely polymerized monomer or a mercaptan compound in the melt. Frequently a mercaptan is used as monomer inhibitors to prevent polymerization prior to initial processing. Mercaptans are sulfur containing organic compounds and are very pungent at low concentrations in the air.

Thanks for the input so far. My problem is that the people I have in the area will test for gases, but I have to tell them which specific gas I am looking for.

The smeel is not sulfuric, but more of a sweet chemical smell. I'm thinking its along the lines of a formaldehyde. Am I off base with this line of thought?

They do not have to know the gas they are testing for before they perform any test. Simply inject the sample into a Gas Chromatograph or Nuclear Magnetic Resonance Imaging and you will find out the culprit-gas responsible for the repulsive smell.

Do you know of any good testing facilities in the Toronto area?

My regrets for getting back to you so late; but you know the pressures of work.

Anyway, that said, unfortunately, I do not know any testing labs around Toronto. I have not lived in the Toronto area since oh, the days of Yor.

However, I should think that the phone book together with some interviewing questioning of the lab should be helpful.

I doubt it's formaldehyde, it has a characteristic odor, but I woudn't call it "sweet". If you ever spent much time around a university biology lab, it's what they usually smell of. That sounds more like a leftover from the synthesis process. Ethylene and methylene both have a "sweetish" odor. Unless the sampling is done by Draeger tube or similar, it shouldn't be necessary to know/guess what it is first. Chromatography and spectroscopy can pick out various components.

Phosgene has a sweet odor

a breakdown of chlorinated products or combustion

Just curious, but what would be the process/reaction mechanism in the film blowing process that creates this phosgene? I am interested in learning the source of the Chlorine for forming the phosgene.

One possibility is if they're using methylene chloride as a synthesis feedstock. It's faily common since it can be transported as a liquid in tank cars and trucks, rather than using a gas feedstock.

I believe that the feedstock was polyethylene resins, as it was stated.

Further, it was stated that the situation arises most often during the recycle process, which tells me that there is no longer any issue of synthesis - assuming that I have read the question correctly.

Feedstock is polyethylene. The reprocessed material would not contain PVC, or other polymers as they would not blend with the PE in the extruder.

Air used to inflate the bubble is compressed air, run through a 50 micron filter.

I would think the MSDS should have all this information.

Joe

Joe,

MSDS does not report chemical reactions of chemicals possibly reacting with one another, causing the odour.

MG

Hello Poison,

What is the gas (or is it compressed air?) used which is forming the bubble?

If it is compressed air -

Is it possible that the lubricant (oil) in the compressed air, or is it possible that the smell of the air as it arrives from the compressor the culprit?

I may be off beat here, as I am not familiar with the blowing process - just a thought, easy enough to check!

MG - Ontario

In film production cetain slip agents based on Eucricimide (Sp) or other fatty acid chemicals are used to prevent the film from sticking to itself. Perhaps that is the odor.

We use euricimides as our slip agent. I'm noticing the smell is worse when using reprocessed material. Repro may also contain the remains of ink used on the old film. Our ink is solvent based. Could we be smelling alcohols, Naptha, etc?