Chemists needed!

[arcwick08]

Maybe somebody who didn't fail high-school chem like yours truly can help me out.

Somebody pointed out to me that the little plastic bags that most pen parts come in are magically (yes, it is magic) immune to CA.

My question is; What type of plastic/polymer are these bags made of? I had some ideas for other applications where a ca-resistant plastic would be of use...

Cheers!

ac

 

[Pens By Scott]

Not a chemist, but just searching on the internet and picking the brand name Zip lock it appears the Zip Lock Brands are made from polyethylene plastic with a softening point of approximately 195 degrees Fahrenheit.

As for the ones the parts come in, i'd guess they are made for the same, or something similar.

 

[SDB777]

I thought the baggie just kept the glue from sticking to your finger through the paper towels....didn't think they were 'resistant'?


Have I been missing out on a great thing....







Scott (figures) B

 

[arcwick08]

So far as I can tell, I can't make ca stick to the baggies... It just runs off

 

[Timbo]

Polyethylene. No common glue or caulk will stick to it.

I used polyethylene sewer pipe to make my tent weights. During my research to find a glue to secure the cheapo PVC caps to the pipe I found one company that claimed to have a glue for it...but it was way too expensive to consider. I secured the tops with sheet metal screws. I used caulk also, but that was just to keep the sand from escaping. The caulk I got on the polyethylene pipe easily peeled off after it dried.

 

[studioso]

I work for a plastic sheet manufacturer.

Polyethylene, either high density (hdpe), medium (mdpe) or low (ldpe), is extremely resistant to many chemicals and glues. Some glues or tapes might stick to it initially, but will eventually fail.
Those little bags could be polyethylene, but I think they could also be polypropylene. (pp). Pp is a bit less resistant to glues/chemicals.

 

[arcwick08]

Any easy way to find whether it's polyethylene or polypropylene? Not that it really matters.. Just curious at this point.
Incidentally, I'm pretty sure in have socks made of 'polypro'... I guess we're not exactly talking pens anymore though!

 

[studioso]

by us in the plastic factory they have some chemicals they use, plus they do a burn test. these are good methods to distinguish between styrene, ABS and ethylenes, but between HPDE and PP it's less obvious. I know that HDPE will bubble when it burns, and pp will "retreat" and curl unto itself, but that is visible in thicker sheet, not sure you can tell when burning film (or thread). also, they smell different. not sure how to define it, HDPE is more waxy. smells a bit like a ski shop, when they wax skis and boards. PP smells more like old celluloid, you know the smell when you open an old reel case...
again, that works well with clear sheet: not sure of the grade they use for film is different.

 

[1080Wayne]

The bags are almost certainly LDPE