Solvent for PDMS
Filed under: Chemistry,Engineering,General,PDMS,Technology — nobrainer @ 10:44 am

So, you’re looking for a PDMS solvent. I bet you’re having a difficult time, and mostly finding scholarly articles that you either can’t access or that don’t actually have what you’re looking for. Well I’m going to provide some summary data for a very useful paper published in 2003 by Jessamine Ng Lee, Cheolmin Park, and George M. Whitesides. In their paper, Solvent Compatibility of Poly(dimethylsiloxane)-Based Microfluidic Devices, (you may be able to access the abstract and full text versions here), they report on the efficacy of various solvents for cross-linked PDMS.

For 38 different potential solvents, they immersed their samples of cross-linked PDMS and measured the amount of swelling. Most solvents won’t dissolve PDMS. The best solvents and the measured swelling ratios are listed below, along with a few very common, but less efficacious solvents. (Below all that are the chemicals that can completely dissolve the PDMS.)

Solvent Swelling Ratio
diisopropylamine 2.13
triethylamine 1.58
pentane 1.44
xylenes 1.41
chloroform 1.39
ether 1.38
tetrahydrofuran 1.38
hexanes 1.35
trichloroethylene 1.34
n-heptane 1.34
toluene 1.31
benzene 1.28
acetone 1.06
ethyl alcohol (ethanol) 1.40

If you actually want to dissolve PDMS, the paper says that 3 different items will do it: dipropylamine, sulfuric acid (18.0 mol/L), and trifluoroacetic acid (13.4 mol/L). It also notes that it took 39 days for the dipropylamine to completely dissolve the PDMS. It is important to note that these processes may all take days or weeks to complete.

UPDATE [2010-03-07]: A copy of the paper I was referring to has been uploaded to Scribd.


Why big oil fears acetone!
Filed under: Acetone & Gasoline,Energy,General,Technology — nobrainer @ 8:25 pm

Louis LaPointe has a secret. And he’s sharing it with the world, for folks like you, out of the goodness of his heart. By adding a tiny amount of acetone to your gasoline you can increase your mileage by up to 35%! He even has a chart to prove it!

And it has big oil shaking in its boots.

They’re totally going to lose a ton of money.

You see, acetone is an organic solvent. It comes from various sources, but the most common source is cumene hydroperoxide.

Cumene hydroperoxide comes from isopropylbenzene.

And isopropylbenzene, is also known as cumene.

And cumene comes from… Crude oil?


Acetone is an oil derivate. Shell Chemical LP makes acetone. Shell is probably the 2nd biggest producer of acetone in America. It’s led by Sunoco. Combined they own 49% of the acetone market. And Citgo is 48% owner of another venture that accounts for 11% of the market.

So show those greedy corporate oil bastards by buying their product!

Re-visiting the Acetone in Gasoline concept
Filed under: Acetone & Gasoline,Energy,Engineering,General,Technology — nobrainer @ 3:47 pm

I’ve previously cast my thoughts on the acetone improves mileage concept. I still think it’s a myth, but like the good little scientist I am, I’m always up for being proven wrong. It turns out that the main propagator of the idea, Lou LaPointe (who also goes by C. L. LaPointe, and Louis LaPointe), updated his files sometime in 2006. There is a lot of stuff to read, but not very much useful information; it’s rather long winded, ill organized, and full of entirely too much conspiracy theory. To avoid being long winded myself, there are 4 main points I want to hit on today.

1.) Have you read the finer details of his testing?
2.) Did you notice he says that it’s not just acetone that works as a mileage enhancing additive? Let’s look more at xylene, and some of the others.
3.) There’s a researcher at Clemson University who has confirmed positive results?
4.) If it’s a surface tension problem, let’s study that.

To some extent this is incomplete and ongoing research. This is the presentation of what I’ve found thus far.



Acetone in Gasoline – BUSTED!
Filed under: Acetone & Gasoline,Energy,Engineering,General,Technology — nobrainer @ 11:03 pm

[Editor's note: In recent tests, I got only a moderate, 5%-8% (if that much), improvement due to acetone. Also, click the above Acetone & Gasoline link to see the most recent posts on the topic.]

Mythbusters finally tackled the issue and tested car performance with acetone mixed with gasoline. Was the mileage improvement touted by Louis Lapointe confirmed? Plausible? No. And no. Totally busted.

They didn’t test the full range of mixtures, but said they used about a 500:1 gasoline:acetone ratio. That’s about 2.56 fluid ounces per 10 gallons.

Fuel mileage curve with acetone

Just like the engineers at Kettering University, no improvement due to acetone was found. In fact, it looked as though mileage was decreased in all four of their scenarios (2 speeds times 2 cars) on the dyno.


UPDATE: whoops! I thought tonight’s episode was new. I was wrong, according to Wikipedia it aired on May 10, 2006. And crazy ol’ LaPointe defends himself in his FAQ (seriously, read it and decide for yourself that the guy is nuts): (more…)


stopping junk mail (credit card offer opt out)
Filed under: General — nobrainer @ 10:21 am

I can’t remember if I posted this before today, but you can choose to no longer receive credit card applications in the mail. By calling either 1-888-5-OPT-OUT or visiting OptOutPrescreen.com you can slow all those applications to a trickle.

These applications used to bug the crap out of me. CapitalOne was sending me multiple applications per week. Sometimes I even received multiple applications per day. I also despised the packaging and how they tried to make it look like something other than junk mail and maybe even something important.

Fortunately I found out about the Opt-Out process through one of my actual credits cards. I looked into it and jumped at the chance, probably more than a year ago. And as the website says, the offers don’t stop immediately but after a couple months such offers had become pretty rare. In fact, my volume of mail has decreased so much that I get a little sad when I see nothing in my mailbox for days at a time. Ok not really, but you can use the website to Opt-In if you should so choose.

I’m quite pleased. I’ve spread the info to my family and they’re happy. I know I told some of you regular readers about it via email. Your thoughts?

As a final note, because I haven’t tried it, apparently “you can register for the Direct Marketing Association’s (DMA’s) Mail Preference Service (MPS)” in order “to receive less national advertising mail.” But it’ll cost you. A dollar.


Shaving project update
Filed under: General,Shaving — nobrainer @ 5:10 pm

It’s been a few weeks since I last updated with what was a broad status report.

For the most part, I’ve been sticking with the Shave Secret oil. Combined with a decent razor it is just superb. Since I’ve been holding that variable constant, I have been using many of the razors I purchased. And in the process, my opinion has changed.

The double edged safety razor, while functional, is quickly losing my favor. I need to change the blades and use it some more, but it didn’t seem that the blades lasted all that long, and the odds of me cutting myself are extremely high.

I have also remembered why I didn’t like the Sensor. Using either the regular Sensor or Sensor3 cartridges, debris got stuck in between the blades. Removing it is a pain. Since the Sensor3 has basically the same contact surface as the Mach3, it fails.

I’ve also used the Fusion a bit more. I don’t hate it as much now as I did. I still think it’s too bulky though.

Until I put together a numeric ranking system, I’ll rank the razors this way: if I were going to a job interview or on a big date, I wouldn’t even consider using the Sensor or the DESR.

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