Chemical Resistance of Polyethylene

[shinigami66]

I'm just wondering, what gives polyethylene its property chemical resistance? Does it have something to do with the electronegativies between the C-H bonds and most chemicals are unable to break the bonds between C-H, therefore unlikely to take part in a chemical reaction?
Thank you

Edit: I think I'm asking too much questions...
hmm but how does chlorine atoms in PVC polymer prevents fire? And also how does the bonding make it water resistant?
This is like a research task and I couldn't think why these properties can be related in terms of bonding :(
Thank you so much!

 

[wowolaf]

There are a number of reasons polyethylene has strong chemical resistance. Most of these stem from polyethylene's makeup - it's a long, long chain composed entirely of carbon and hydrogen.

Because of this, it isn't a very polar substance, so there's nothing on the molecule that interacts readily with water (a very polar molecule). Being aliphatic, it's also largely unaffected by interactions with aromatic solvents. It's lacking in any functional groups (esters, amides, etc.) that would be susceptible to nucelophilic attack or oxidation, so those sorts of reactions are out too.

Basically, it all boils down to the simplicity of polyethylene's construction. If you've taken ochem, you probably know that C-H bonds are fairly difficult to break (hydrogen is a terrible leaving group), and that's all polyethylene is.

I'm at work now, so I haven't confirmed this, but off the top of my head, I'd guess, simply, the chlorine in PVC prevents fire by reacting with the many radicals present in flame and stopping the exothermic reactions from propagating.

If you have any questions, I can try to clarify later; in the meantime, a google search on halogenated flame retardants might shed on some light on the mechanics behind your PVC question.

 

[quicknote]

Dear curious scientist,

Thank you for your questions about the chemical resistance of polyethylene. Polyethylene is a type of polymer that is made up of long chains of repeating units of ethylene monomers. This structure gives it its unique properties, including its chemical resistance.

The chemical resistance of polyethylene is due to its strong carbon-carbon bonds, which are difficult for most chemicals to break. The electronegativity (ability to attract electrons) of carbon and hydrogen atoms is similar, so there is no significant difference in charge distribution within the molecule. This makes it difficult for other molecules, such as chemicals, to interact with the carbon-hydrogen bonds and break them.

Regarding your question about chlorine atoms in PVC polymer preventing fire, this is due to the presence of chlorine atoms in the polymer chain. The chlorine atoms act as a flame retardant, releasing hydrogen chloride gas when exposed to high temperatures. This gas helps to dilute the oxygen in the surrounding air, making it difficult for the fire to continue burning.

As for the water resistance of polyethylene, it is also related to the strong carbon-carbon bonds. These bonds create a tightly packed and non-polar structure, making it difficult for water molecules (which are polar) to interact with the polyethylene molecule. This results in the water being unable to penetrate or dissolve the polyethylene.

I hope this helps to answer your questions. If you have any further inquiries, please feel free to ask. Keep exploring and learning!

Sincerely,