Sciencemadness Discussion Board

TEFLON (PTFE) beaker users? Chinese products???

Bert - 10-4-2014 at 06:45

I have been seeing (relatively!) cheap Chinese made? PTFE beakers showing up on eBay recently-

I've never used one. I do understand the need for non reactive beakers with such things as hydroflouric acid and extremely basic materials.

Has anyone used these items? Are they made properly...

(Flagrant racial stereotype driven idiocy on Bert's part removed here)

TEFLON structural materials are fabricated by a powder pressing and sintering process, as far as I recall. I would assume porosity could be a problem?

If you use such equipment- What do you think of them? And what am I not thinking of, both in terms of real world need for this type of material in lab processes, and what the drawbacks of these cheap tools may be?

[Edited on 10-4-2014 by Bert]

[Edited on 13-4-2014 by Bert]

Zyklon-A - 10-4-2014 at 07:21

The first link doesn't work for me, it just sends me to eBay.com. No, I haven't bought one, but I might.

Varmint - 10-4-2014 at 07:44

My first concern would be thermal conductivity, in both directions.

1). You need a reaction that takes place at an elevated temperature (or are heating up for evaporation), the lower thermal conductivity can present a problem.

2). You are doing an exothermic reation where you would normally count on an ice bath (or indeed just plain air) to control the temperature. Again, but in the opposite direction, thermal conductivity can present a problem.

Given those limitations, I'm hard-pressed to think of an application where they would fit my needs. That doesn't mean there aren't any, just that I don't see it right off the bat.

The presumed immunity to breakage under typical conditions IS attractive, but I'm not sure what kind of premium I'd be willing to pay over borosilicate for the limited number of applications where the drawbacks don't come into play.

DAS

Chemosynthesis - 10-4-2014 at 08:47

I have seen Teflon used in some pressure applications such as hydrogenation work, digest bombs, autoclaves, and even microwave reactions. I'm not sure why microwave reactions might prefer Teflon, or why beakers outside the cases you have mentioned, as the microwave accelerated reaction system and my limited but interesting microwave synthesis days always used glass vessels.

edit- just thought of one possible use, though I know there are others I can't explain... there are microwave digestion bomb methodologies I have never seen used.

I always thought most uses for non-glass lab ware, outside of HF, was to save money by making it hard to break by dropping, reducing replacement costs.

[Edited on 10-4-2014 by Chemosynthesis]

macckone - 10-4-2014 at 09:07

PTFE is not resistant to concentrated hot NaOH. It strips the fluorine
off the polymer leaving a tacky mess of the coating. PTFE will also absorb
HF. But doesn't seem degraded by it. Stainless 316 is better for NaOH.
And nickel is the preferred material for HF. Or at least that is what is
used industrially.

blogfast25 - 10-4-2014 at 10:23

Try and get reasonably priced, smallish size nickelware though...

macckone - 12-4-2014 at 15:45

Yes, nickle crucibles, 50ml run about $35.

deltaH - 12-4-2014 at 15:53

On the topic of crucibles, I used to do sodium peroxide fusions of mineral samples for metal assays in zirconium crucibles over a decade ago. They were tough as nails but cost a pretty penny back then!

Before that we were doing HF digestions, initially in pyrex (simply sacrificing the beakers after a few uses) then later in teflon bombs, but we had to switch over to the peroxide fusions to quantitatively dissolve up some tougher ore components like chromite if I remember correctly.

For the 'wet' digestions, the Pyrex was suprisingly tough even to the HF, though the beakers were consumables in that lab.

[Edited on 13-4-2014 by deltaH]

Bert - 12-4-2014 at 19:25

Thanks everyone, I've learned a few things from this-

Not going to need the PTFE equipment anytime soon, hydroflouric acid is not on my list of reagents I'll be needing for any planned projects.

Bert - 13-4-2014 at 06:27

I am pretty happy with the information on less reactive/non glassware vessels this thread generated.

Thanks again, everyone!



If their is an additional side discussion of interest to the members on the intersection of laboratory GLASS, quality control, marketing practices, societal or cultural perceptions vs. actual norms- AND IF IT's RELEVANT TO AMATEUR CHEMISTRY- Let's start that up on Legal & Societal.

If it goes there, Keep it clean, stick to personal experience & verifiable incidents and no ad hominem...

blogfast25 - 13-4-2014 at 11:03

Quote: Originally posted by Bert  
If their is an additional side discussion of interest to the members on the intersection of laboratory GLASS, quality control, marketing practices, societal or cultural perceptions vs. actual norms- AND IF IT's RELEVANT TO AMATEUR CHEMISTRY- Let's start that up on Legal & Societal.

If it goes there, Keep it clean, stick to personal experience & verifiable incidents and no ad hominem...


That could be useful, as well as interesting.

[Edited on 13-4-2014 by blogfast25]

Bert - 13-4-2014 at 14:14

I removed whatever seemed not relevant to the discussion of PTFE and other non glass containers and their uses.

Their will be an even handed, documented fact & evidence based discussion on Legal & Societal regarding equipment sources and quality control issues.

blogfast25 - 14-4-2014 at 04:41

Quote: Originally posted by Bert  
I removed whatever seemed not relevant to the discussion of PTFE and other non glass containers and their uses.



I'm not sure blatantly removing people's posts (or parts of it) is going to please many: they put work into putting those texts up. Surgical removal to 'Detritus' is the usual procedure for stuff that is deemed irrelevant/unsuitable to a thread.

Bert - 14-4-2014 at 09:58

I watched a thread deteriorate into a borderline flame war, with several who should know better spending a lot of words on having the last word, regardless of the thread's original purpose. The only thing being learned was that smart people will get stupid and argue on the internet.

Tried offering an alternative to this sideshow, in an appropriate place for the derail's subject. Got no traction, you may have missed a few things I deleted. I certainly hope you did.

People may hate me if they feel slighted by my actions in maintaining what semblence of order I can here. I will just have to deal with that somehow.

Look at the history of active moderation here, and quality of threads generated vs. level of scrutiny and moderator activity. Would you rather there was none?

I will leave any answer you care to make here and say no more. As a peace offering, please have the last word.

macckone - 14-4-2014 at 11:48

As a last word from a post that was removed.
Everyone should be cautious with pyrex branded beakers.
Some are borosilicate, some are not.
And this is legitimate pyrex trademarked ware.
After corning sold off the brand name the new
maker no longer uses borosilicate for most products.

http://www.snopes.com/food/warnings/pyrex.asp

blogfast25 - 14-4-2014 at 12:26

Quote: Originally posted by Bert  

Look at the history of active moderation here, and quality of threads generated vs. level of scrutiny and moderator activity. Would you rather there was none?




My point was merely that posts are rarely deleted, rather they are usually moved to detritus. Nothing else. I have no problem with moderation per se.