Friday, April 30, 2010
Undoubtedly the chemical is a contaminant that wasn't identified because a control wasn't run.
Thursday, April 29, 2010
In DNA (and RNA), all the attention is focused on the bases, (adenine, cytosine, guanine and thymine, the A, C, G and T) that create the "code of life". The hydrogen bonding that occurs between the A and the T, and the C and the G is at the heart of the double helix. However, these bases are all attached to a phosphate, and each phosphate is attached to another. These phosphates are the polymer backbone of DNA - the bases are just moieties. And as become more apparent with each passing year as new discoveries are announced of prehistoric DNA being recovered from ______________, these phosphate chains are extremely stable.
At the same time, phosphates are also used in energizing life. As adenosine triphosphate and adenosine disphophate are interconverted, energy is given and taken away from the cell, a reaction that happens extremely quickly, in contrast to the stability of the phosphate backbone of DNA.
"Why Nature Chose Phosphates" from Science in 1987 (open access) also has another perspective on why phosphates are heavily used in biochemistry, far more than in most organic chemistry. (Are there even any commercially available synthetic polymers with a phosphorus backbone?)
Wednesday, April 28, 2010
Simply put, the steady state shear viscosity at a given shear rate is equal to the dynamic viscosity at the same frequency:
h() = h*(w) when = wThe rule is more-or-less empirical - it works for many common polymers but there is no (strong) theoretical background that it should work for all polymers and it certainly doesn't.
I'm always happy with anyone asking me the question as it is a terrific one and shows that the person is seriously thinking about what is being tested. There are way too many tests that do not match up with reality in the least, and too many people do not question the differences.
If you can answer that, then take a swing at these followups too:
The word should be banned from the English language (all languages for that matter, assuming that other languages are as bad as English in this regards.)
Tuesday, April 27, 2010
So Lyondell is now coming out of bankruptcy, but some of the reports are really making me question if I understand math correctly. This report (courtesy of the Urethane Blog) states near the bottom that the proceedings were costing the company $50 million a month, but at the same time, the total debt was reduced by about $17 billion.
Since they were in bankruptcy protection since January, 2009 that is 16 months. So how can reducing debt by over $1 billion/month while costing you on $50 million/month be a bad deal?
Monday, April 26, 2010
[*] The planes themselves are definitely a fixed costs borne 24/7, which then forces the airlines try to run them as much as possible. While this is not 24/7, it is still an appreciable fracture of that - hence the quotations on the term "fixed" above. Of course, a further variable on this "fixed" cost is the fluxuating price of the fuel.
Friday, April 23, 2010
Normally I would be inclined to state that the bankers and lawyers are the only ones making out on all these deals, but given the healthy growth of the venture of the years, I think everyone is doing o.k.
[*] For anyone reading this without knowledge of baseball, the title of this entry is something that is shouted outside of baseball stadiums by people selling "scorecards" - glossy magazines with information about the players, the team,... Further regarding baseball, the deja vu quote is from a famous baseball player, Yogi Berra, now better known for his tautologies than his feats on the field, even though he was quite a good player.
My first job after all my schooling was making packaging films out of PP, so I cen relate to some of the challenges mentioned in the article. The sealant appears to be needed as the PLA must melt at too high of a temperture to allow for a quick thermoseal. And the sealant can only seal to itself, forcing the use of a fin seal rather than a lap seal.
One interesting bit of trivia I learned all those years ago is that potato chips need to be kept in the dark - you don't see any bags with windows in them as you do with corn chips. The light apparently will cause the oils in the chips to go bad.
So how can the metal layer be considered biodegradable?
Thursday, April 22, 2010
But then the authors goes right on the cliff of irrationality with these comments:
"If we fail to meet this challenge, humanity faces a Malthusian trap of widespread famine on a scale that we have not yet experienced."
This was so shocking as just in the previous paragraph, they had clearly stated that
"... unlike fossil fuels, phosphorus can be used over and over -- this is what occurs in natural ecosystems, where it is recycled innumerable times from its first mobilization from the Earth's crust to its eventual deposition into lake and ocean sediments."
Why they felt an urge to sway to the grand exaggeration and fearmongering is beyond me.
Wednesday, April 21, 2010
The curved surfaces are sculptures on both ends of the new 35W bridge. The surfaces of the sculptures are coated with TiO2 which reduces pollution in the immediate vicinity. Not enough to do any real good of course.
I’m not going to attempt to explain the reaction mechanism of photocatalysis – it involves a good deal of solid state physics (something I have no formal training in) and is an area still being actively studied. Inconsistent results are sign (in any field for that matter) that everything is still not understood or in control.
This is all prelude to a report that came out a few months ago about a new photocatalytic surface that not only uses visible light (that in itself is not new) but that the surface is capable of still running after the light is removed. TiO2 normally need UV light to activate it, but when doped with nitrogen, visible light works just fine. In this case, they also added palladium oxide nanoparticles to the surface. The nanoparticles appear to work as a trap for the activated electrons which are then released in the dark.
The curious part of this entry is that all of these are degradation reactions – I’ve yet to see a photocatalytic reaction that is used in a curing or other building reaction. Just degradation. I led into this entry with the idea that UV light can be both productive and destructive, but I’m not so sure that this is the case with photocatalysis.
Apparently they normally are made of nylon; I would imagine that this is used not only for the tensile strength, but also it's ability to create and keep the locking ratchet. Olefins should be strong enough for the tensile properties, but I would have doubts about the lock holding.
Sarlink has now announced that a client is producing TPV based flexicuffs. (TPV's are an olefin with a dispersed rubber in the matrix.) I'm rather surprised for a couple of reasons - not only because the tensile properties are lower than nylon (the modulus for nylon is about 2 GPa, while that for the chosen grade of Sarlink is about 100x smaller - 18 MPa)but also that the locking mechanism would be useless for anyone but the above noted five-year old. This is a 45D Shore hardness material and I really am having a hard time imagining that the lock would hold. But I also can't imagine that the manufacturer didn't do some extensive testing too.
Tuesday, April 20, 2010
while in his type II reaction, the photoinitiator stays together as one molecule. Wouldn't it make more sense for the Type I to be the reaction where the PI stays together as 1 molecule and a Type II to be the reaction with the PI breaking into 2 parts?
But who am I to criticize? He's got a Nobel Prize, and I? Well I know how to spell "Nobel Prize".
I imagine that this was simply the ordered in which he discoverd the reactions.
Monday, April 19, 2010
I'm not an expert on skin absorption of drugs and chemicals, but I have noticed over the years that the skin of the finger tips and palms seem to be far, far less porous than that of the rest of the body. For example, I've had poison ivy outbreaks (caused by absorption of urushiol) all over, but never in the palms. I've talked to others who spend time in the woods and they all report similar experiences.
So maybe that first exposure was an "accident". Or maybe it wasn't. But I seriously question the claimed exposure route.
[*] Not me. I haven't even tried pot! Imagine how embarrassing it would be to appear before the Senate Judiciary Committee or some such entity and having to state that fact? Think someone that out of touch with society would stand a chance of getting confirmed to even dog catcher?
Friday, April 16, 2010
But wait, there is a second such environmentalist out there.
I'm excited about this new trend. How do we keep it going?
I've little experience in aircraft construction, so I don't know about how other parts are attached, specfically the tail section, so this report on a new welded thermoplastic tail section caught my interest. Thermoplastics tend to deform more easily than thermosets  so I thought that their use would be avoided - although the tail is made of PPS, a pretty tough plastic. But more than that, I'm not sure what advantage there would be in the welding operation, as it would require more expensive equipment than a standard adhesive bond (again, I am assuming that it is an adhesive that is used). Apparently the entire tail is made of PPS, cetainly a weight/fuel saving move.
 O.k., so I'm overplaying my hand a bit. There is a chain of linkages that holds a plane up - but the adhesive, being small and invisible, doesn't get the credit it deserves.
 A plot of the mechnanical properties for thermoplastics and thermosets would show two peaks with overlapping tails. The averages are clearly offset, but there are still specific examples that contradict the averages.
Optically transparent and electrically conductive thin films composed of multi-walled carbon nanotube (MWCNT) reinforced polymethyl methacrylate/acrylic acid (PMMA/AA) were fabricated using a wire coating technique. Poly(acrylic acid) controls the level of MWCNT dispersion in aqueous mixtures and retains the well-dispersed state in the polymer matrix after solidification resulting from extended polymer chains by adjusting the pH value. The exfoliating the MWCNT bundles by extended polymer chains results in the excellent dispersion of MWCNT. It causes a lower surface electrical resistance at the same MWCNT content. The hydrophilic functional groups (−COO − NA + ) also caused a decrease in the crystallization of PMMA and led to an increase in the transmittance.PMMA is not crystalline unless special steps are taken to control the tacity of the material - and adding acid comonomers will only make the situation worse. The only evidence to supplied to support the claims of crystallinity is an XRD plot showing a peak. This is not enough as the XRD of PMMA normally shows peaks anyway.
For such a statement to pass through in the abstract is incredible.
Thursday, April 15, 2010
Wednesday, April 14, 2010
1) Dynamic mechanical analysis. It's one of the most fundamental measuring techniques in rheology. A modulated strain (or stress is you have a newer machine!) is applied to the sample, and out pops the storage and loss moduli (or the corresponding compliances or tan delta or viscosity or whatever function your heart desires). Without the modulation, you can only get the viscosity - as in a capillary viscometer.
2) Modulated DSC. By adding a sinusoidal overlay on the temperature ramp, you are able to separate out reversible and irreversible transitions, and do it with more sensitivity than with a linear temperature ramp.
I've been aware of these previous two examples for nearly 20 years, but a ran across a new one yesterday .
3) US Patent Application 2006/0228806, "Method for detecting the modification of a characteristic of a sample caused by an enviromental influence". This is a technique for determining degradation in polymers due to natural/accelerated weathering. A very common technique is to use a spectrophotometer which gives the standard L,a,b values (or CIE values or ...). This new method applies a mask to the sample during the exposure time, providing geometric modulation. During testing, the mask is removed and the entire samples is scanned on a flatbead scanner, a much cheaper and more common device than a spectrophotometer, although not without its disadvantages too. Using correlation techniques, changes in the sample can be detected much quicker than by using absolute measurements. The equipment has been commercialized; I've not used it so I can't say anything about it.
So now that I see a three-peat, I can see the bigger picture: modulate whatever you can whenever you can.
 The new Atlas-MTS Newsletter, "Sunspots", Spring 2010 in the lead article mentions the techique as a "Ten Times Faster to Result" method. The Public PAIR site shows that the application is still active after. Applications were also filed in Europe too and I don't know what the status is on those.
 Spectrophotometers are essential for field work. You can't use a flatbed scanner to look at color changes occuring in an installed window, a common occurance for us and our parent corporation.
 The Catscope, from ERT-Optik. Warning: the site is in German, but for us old school chemists who had to learn German, that's not a problem, is it?
Tuesday, April 13, 2010
Monday, April 12, 2010
The University of Akron is a counter example, having an entire college devoted to the subject.
Feel free to suggest anything that I'm missing. I'm not saying the list is complete by any means. At some point, it may need to move to a different page and be organized under different headings rather than just a big unworkable list.
Friday, April 09, 2010
Even before these newest trends away from solvents, I had noticed that most chemists didn’t really understand them in any quantitative sense – they were just a carrier matrix for whatever else of real importance was dissolved in them, and that a trial-and-error approach was sufficient.
This is a shame as solvents make it so much easier to work with polymer on a lab-scale. Extrusion coating is best done on large equipment – it is just too difficult to do it when you only have 10 grams of material, but if you dissolve those 10 grams, then you can use any of a number of drawdown techniques to make a coating.
All this is a big lead up to this: a report (open access) of a new[*] group of solvents (amidines and guanidines) that can be switched from hydrophilic to hydrophobic just be bubbling CO2 through it. (One of the solvents can even be switched back.) As you would expect, the CO2 is converted to carbonic acid. This then suddenly provides an easy handle to adjust solubility and precipitation. The paper provides an examples focusing on soybean oil extraction. The extracts are not polymers, but that doesn’t matter – the thermodynamics are the same regardless of the solvate. Bubbling CO2 is an easy switch to operate too. The most common alternative options are to evaporate the solvent off with heat or precipitate it out with the addition of a non-solvent. (With polymers, you can sometimes get cute by just adjusting temperature if the system has an upper or lower critical solution temperature (UCST/LCST).
[*}These aren't "new" solvents - they were all purchased from existing suppliers. This report just recognizes the previously unrecognized properties.
Thursday, April 08, 2010
I am quite excited about the talk. As I've mentioned before, I love working with UV light, and I very much enjoy presenting my work to others. This was a nice project that will make a good presentation, even if UV curing isn't your area of work.
Here is a hint of the talk:
A client approached us with a floor coating system that was perfect in every way except one - it took much too long to cure. Accelerating the cure was far, far more difficult than imagined. We threw everything we could think of at it and kept failing. We did finally nail it, delivering a 20x increase of speed, thus disappointing the client who only wanted a 10x increase.
So what was the breakthrough? You'll have to come to the talk to find out.
Being in R & D is a life with many more days of frustration and disappointment than accomplishment, but this was one of the latter. I just found out yesterday that the FDA had finally approved the Esteem Hearing Aid and couldn't be prouder. My pride comes from having worked for the company solving technical problems so that the clinical trials could start again.
This moment was a long time coming - 15 years in fact. The product had been through a number of ups and downs - I was always amazed that people would continue to fund the start-up for so long - $120 million was invested!
When I was there, there were 25 people or so employed - the smallest company that I have ever worked for. Being that small everyone had to pull their weight and there was limited division of labor. If more parts needed to be built, anyone and everyone could be called in to help. With 25 people, you were 4% of the company's output. If you were a slacker, that would be quickly noticed, unlike at a company of say 25,000 where you are only 0.004% of the output.
Wednesday, April 07, 2010
One stop was Gun Barrel City. There's something about that name that is so Texan in my mind. When colleagues found out where I was going, they asked if it was in the dry or wet part of Texas, to which I had to answer it was in the gun toting part of Texas. A little southeast of Dallas, the scenery was nothing to comment on. The large reservoir was pretty low, and certainly we have many more beautiful lakes in Minnesota.
On another trip, I was close, but never got a chance to see the Grassy Knoll. My meeting that day ran long and I had a plane to catch. I suspect it would have been a letdown, as afterall, it is just a grassy knoll.
The highlight of my "Tour de Texas" however, was a side trip:
This would only be meaningful to country music fans, but the city is quite famous in the genre from the songs of Waylon Jennings (with Willie Nelson), Jerry Jeff Walker, and others in more recent times. The picture is me in front of the Post Office - there's a bar in the back of the building. The music hall is off to the left. And that's it for the town. Truly a town where if you blink, you will miss it.
It's in the Hill Country between Austin and San Antonio, a stunningly beautiful and serene part of Texas. I can't wait to return. I took some pictures, which despite being technically proper, just didn't capture the essence. I'm not posting them.
Lastly, if you like a puzzle, then consider this: what type of work (related to polymers) would possibly involve traveling the back parts of Texas in a suit and tie? (And yes Waylon, they were choking me.)
That's what I love about this job: I can never predict what will happen next.
Tuesday, April 06, 2010
Again, this is not necessarily a bad problem as it shows strong support for the growing industry. The technology is being developed to manufacture these large blades, which in some cases are as long at 80 meters. The rotor blades are deflected repeatedly to simulate the service life (not unlike the testing that airplane wings need to undergo). New facilities are being built around the world, and it is the engineering needed is understood – no breakthroughs are required.
Monday, April 05, 2010
The World Polymer Notes blog is a good site cataloging everything that has been made to date. Usage of polymers as the base for the notes has an unusual geographic distribution, mostly below the Tropic of Cancer.
I love the irony of this concept: these are floating islands constructed from fiberglass embedded with various acquatic plants. These can be used at golf courses and other enclosed lakes and aimed as a natural method to improve water quality. (The plants uptake nitrogen and phosphorus from the water making them unavailable to algae.)
Anybody see any similarity between these and the "Great Pacific Garbage Patch"?
They look like flow marks but aren't. These are photos from various polyolefin materials around my house that have been exposed to the sun for a number of years. The additive package designed to prevent this has been consumed and the UV photons are now having a free-for-all. The changes are largely cosmetic, but will eventually become structural.
I'm not sure why the variation exists, but in an almost contradictory statement, I think it could be related to the flow in the mold. I'm hypothesizing that these ARE basically a flow mark, but the marks could not be seen because human eyes are not sensitive enough to detect the original defect. Now after 10 years in the sun...
To further support this idea, I've worked with compression molded PP parts that were also strongly oxidized, but that oxidation was much more uniform than in these injection molded parts.
Thursday, April 01, 2010
Senator Ima Windbag released today a set of double-secret, triple confidential internal memos from the Bisphenol-A Research Foundation (BARF) showing that the group, in an effort to assure wide usage of bisphenol A (BPA) in the future, had researched and developed modified forms of BPA that led to consumers becoming physically addicted to it. Dozens of different variations were produced and tested, but the memo specifically found that opiate-modified BPA was the most effective at forming the addictions.
The shocking memos revealed test results using rats showing that once exposed to polycarbonate and other plastics using the modified BPA, the animals were relentless in their pursuit of the chemical. Researchers found that the animals initially just licked the linings in food cans, but as the addiction worsened, ate the entire can. Still unsated, they started consuming the music CD’s and DVD’s at the lab. The unidentified author of the memos provided a bit of personal insight: “At first I wasn’t concerned because they ate a Justin Bieber CD that belong to my daughter. I thought the rats had good tastes. But when they ate my “Gonna Take You Downtown" CD by Beau Jacque and the Zydeco Hi Rollers, then I knew we had a winner”.
One potentially positive suggestion of the report was to create a large swarm of addicted rats and drop them overboard in the Great Pacific Garbage Patch where they could swim around and eat all the plastic.
Senator Windbag was indignant about this disclosure and promised a full investigation. The Senator stated: “We need more regulations and rules to prevent these shenanigans. That’s just another reason that I’m in favor of a smaller government which would let us have more freedom to let people run their businesses any way they want. Oh, and God bless America!”