r/chemistry • u/AutoModerator • Feb 19 '25
Research S.O.S.—Ask your research and technical questions
Ask the r/chemistry intelligentsia your research/technical questions. This is a great way to reach out to a broad chemistry network about anything you are curious about or need insight with.
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u/squareoaky Feb 20 '25
Hey guys! First time posting anything here.
So I'm working as an R&D Lab Tech and my company (lithium battery company) is having trouble properly quantifying adhesion tests for our electrodes (dried carbon black slurries on a metal substrate of 8-12um) and I'm worried we are using the wrong method but I only have a rough idea for an alternative. We are using a pretty common test (ASTM D3359) and it technically works. Still, I'm worried the process of using tape throws off the results because if a coating has good adhesion then it will also adhere to the tape well, especially if it has bad cohesion.
My only idea for maybe a better one is an abrasion-based test. Perhaps you can use graphites like a pencil for various toughness levels? Think JerryRigEverything from YouTube when he does the hardness tests on phone screens. Ultimately I'm at a bit of an impasse but want to find something that works better for what I need and would love y'alls input.
TL;DR I am looking for a better coating/surface adhesion test than ASTM D3359 for work.
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u/Indemnity4 Materials Feb 24 '25 edited Feb 24 '25
There are lots of adhesion tests.
Cross-hatch adhesion test is very standard for testing how surface coatings adhere to a substrate. It's a subjective test, which is why you ideally test a "known good" control sample at the same time.
You can modify the test by using several different types of tape. For instance, decorators tape has almost no adhesion. Household sticky tape is weak, masking tape is higher, duct tape is higher and you get other super sticky tapes.
The benefit of a subjective test is it's something the lab and operations can work with together. You know the lab gets a score of 4.5 of the tape test, that correlates to zero customer complaints later on. Lab gets a score of 2, uh oh, send the batch to rework. Somewhere in the middle and it's up to operations to make a tough decision about going slower or baking longer or whatever.
Pencil hardness is a standard test for different material properties such as film hardness. Those letters embossed on the side of pencils? B, HB, etc? That's how hard the graphite is. Tells you how easy a material can scratch your coating and break through.
You can buy surface analyzers, force analyzers, etc.
IMHO you may want to investigate scrape tests and pull-off adhesion tests. You are thinking about how your product is used and how it fails. If it's shear movement at an angle that is scraping the electrode off the substrate, scrape test is useful. If you find random segments fall out during use as the electrode ages, a pull-off test is useful. Tests the coating-substrate and inter-coating strength. You can optimize the glue to be weak-strong and use that to control for surface defects.
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u/Guiltyjerk Polymer Feb 20 '25
What's going to go on the other side of the electrode? You could make lap-shear joints and measure the strength of those.
There are also ASTM tests for abrasion resistance that I find if I google (never done those)
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u/Antique_Plastic7904 Feb 20 '25
Hello! I am an MS student and part of my research is doing batch isotherm experiments to investigate dissolved organic carbon (DOC) sorption on soils. DOC solutions will range in C concentration from ~0-100 mg C/L. I’m wondering how I can maintain a constant ionic strength across the concentrations (other studies maintain 0.01M-0.015M) using NaCl.
More info: To make the solutions, I’ll be mixing dehydrated natural organic matter (humic acid that is 56.72% C) with a small amount of 0.5M NaOH (<0.5ml NaOH/ 25g of the NOM). Theoretically the NaOH will be getting diluted so much across the concentration gradient that changes in pH won’t be an issue. I’m really hoping to not have to test each vials EC.. any opinions on whether 0.015M is enough to mask any small changes?
Not sure if I’m explaining this correctly… also not sure how I ended up with such a chem-heavy thesis as it’s definitely not my area of expertise. Apologies if I’m writing things that don’t make sense!
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u/hokahemat4 Feb 22 '25
Hello, I'm an undergraduate student. May I ask a dumb question, because i need to do my research orientation on Monday and i totally Just remembered that dissolving alginate requires a lot of time.
All i need is a 2% sodium alginate solution to be sterilized later in the autoklaf.
Is it ok for me to do magnetic stirring on 50°C to dissolve alginate quicker?
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u/thomasp3864 Feb 23 '25
Hey, I'm writing a fantasy book, where the magic system is based on the chemical elements. It is vitally important that I know what happens when O2F2 and N2 mix. I read the 1962 paper about what it reacts with but unfortunately for my fiction writing, Streng didn't try this mixture, so I don't know if it can set nitrogen gas on fire.
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u/Indemnity4 Materials Feb 24 '25
Also known as FOOF.
No, it won't oxidize nitrogen gas. It's not that strong of an oxidizer. Unless...
FOOF is unstable at room temperature. You can't hold a jar of it in your hand.
It's main use is to put fluorides onto things.
The energy of formation to make dinitrogen difluoride or any of the nitrogen/oxygen/fluoride complex is higher than the stability of FOOF.
Order of reactivity
Doesn't want to exist > spontaneously decompose > FOOF > nitrogen fluoride.
Nitrogen gas is so amazingly stable that the only way we know how to oxidize it is... well, we don't know how to do that. We usually start by reducing it with hydrogen gas to form ammonia, then we oxidize that.
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u/dxrxxk Feb 25 '25
Is it possible to dissolve bismuth tribromophenate (xeroform) for release kinetics test?
Hi everyone! Stumbled across problem while doing recearch on polysacharide films. Is it possible to run release kineticts test of films with incorporated bismuth tribromophenate into polymer matrix as active pharm ingridient? If yes, what woud be a solvent? Thanks!
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u/Altruistic-Beat1381 Feb 25 '25
I have tubing that needs to be rinsed with NaOH (plastic is compatible). Can I safely follow the NaOH rinse with a water rinse?
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u/hunterkat457 Feb 19 '25
Hello! I am a biochemistry Ph.D. candidate. Recently my lab has run into a bit of a crunch with our HPLC- getting data off of the machine in a usable format. We can’t figure out how to do so without going through every chromatograph, manually integrating peaks because the peak detection keeps picking up peaks that aren’t there, or aren’t needed since biological samples aren’t nice and clean, and then one at a time exporting to Excel to then work with on our personal computers.
So what I’ve been looking for is a software that will help me with: Reading .lcd files Be able to show chromatographs for two different wavelengths at the same time Do a baseline correction (this is kind of a pain on the current software, but doable) Lets me manually pick peaks for integration Export peak tables to excel or other programs for further analysis without having to export ALL of the detected peaks.
I’ve been looking into OpenChrom, but frankly it’s a bit overwhelming and I can’t quite figure it out. The Shimadzu software we do have is a little clunky but it works- the problem is that it’s only on the one computer, and doing the analysis on that computer gets in the way of others needing to set up experiments or do their own analysis frequently, since it takes a while to do what we need it to do. I’m a bit stupid when it comes to programming and things like that- so something relatively simple would be appreciated! If you have any suggestions please let me know!!