Thursday, December 30, 2010

Adieu 2010...

..and the whole rest of the first decade of this millennium [*]. It has been an extremely challenging 10 years for myself and others close to me, so please 2010 and your ten predecessors, go gentle into that long night and never return. I used to joke that the year I spent in Terre Haute was the worst decade of my life. Not any more!

As for the rest of you readers, I look forward to continuing this blog in 2011. The blog readership has grown tremendously over this year (I am ever so grateful), a trend I hope will continue.

Aspen Research is closed both tomorrow and Monday, so this is the last post of the year. Until then!

[*] Remember, the millennium didn't start until January 1, 2001.

Can You Design the Next Great Symbol?

Winning $25,000 would be a great way to start the new year, wouldn't it?

Cereplast is launching a contest this coming Monday (January 3) for the creation of a symbol that they hope would become the standard symbol for bioplastics.

I've got some ideas, and with my son's graphic abilities, this contest might be all over before it starts :) [*] Complete details won't be available until Monday, so I can't even tell yet when the contest closes, but it would be pretty cool to see a polymer guy win the contest, not a graphic designer or such.

[*] Or then again, looking at the weird corporate logo of my employer, I might just increase everyone elses chances. By the way, I had absolutely NOTHING to do with our corporate logo. NOTHING!

Tuesday, December 28, 2010

Would You Want to Process This Recycle Steam?

Chevrolet is getting some green kudos for taking 100 miles of oil-soaked booms from the Deepwater Horizon cleanup and using them in the new Volt. I'm all in favor of anybody that wanting to use the booms for any other purpose than landfilling them or burning them, but think about this from the viewpoint of a plastic processor: would you really want to put that stuff into one of your extruders?

Keep in mind that this has never been done before on this scale, so there is real risk involved from just that, and yet at the same time, the amount of materials involved (100,000 lbs) is too small to really stake a claim for the future.

I understand that the booms are being "cleaned" prior to this, but still, there will be some oil left, crude oil at that, that will be rather compatible with the polymer in the boom. (If it wasn't compatible, the boom would never have been able to absorb it.) And all that means that the "cleaning" operation will not be 100% efficient, so now you have crude oil in your polymer feedstock. Would you really want to run that? Particularly for something as mission critical as an automobile part? Making widgets for souvenirs is entirely different. Explaining to your customers that the air deflector broke prematurely because it was made from oil contaminated recycle might not go over so well in a few years.

Update on that Epoxy Art Puzzler

As I threatened, I contacted Momoko Sudo about that puzzling drop of epoxy that she posted on her blog and she was happy to reply. She has posted a few comments on my original posting - the long and short of it is that the "wrinkles" are not wrinkles but are the arise from color variations in the resin.

She also added a new entry to her blog about the whole matter. I really recommend you read her posting as she has some new insights not only about her role as an artist, but also about how puzzling the drop can appear to her too if you look at it anew. Her own words say it best, so check them out.

Monday, December 27, 2010


My wife discovered this unusual lineup of icicles hanging off the back of our house:Unusual, in that they form a peak [*] suggesting a Gaussian distribution.

Icicle formation is actually a non-trivial subject. An article available from the Physics Arxiv shows new research from earlier this year on the subject, not just a theoretical model, but also their efforts to create an icicle growing apparatus under controlled (and adjustable conditions). The challenge in the modelling is that the boundary of the icicle is not defined in advance, but is actually the output of the exercise. Combine that with the nonlinearities of flow, heat transfer, external air currents,... and uniquely for icicles, water purity and you have quite a set of equations to work on simultaneously.

This is quite similar to the problems in modeling polymerization fronts - cases where polymerization in a pool of monomers starts on one side and advances through the liquid, also a nasty little problem to solve despite its simplicity to describe and understand.

[*] Let's just pretend that we are all electrical engineers for a moment, shall we, since they are the ones that always have "peaks" upside down from the rest of the world.

Tuesday, December 21, 2010

Uncertainty in Polymer Molecular Weights to Arrive in 2011

Not content to let 2011 arrive in peace and serenity, IUPAC is at it again, in this case changing the atomic weights of atoms from single values to ranges. The current single values are averages of the known natural distributions (Cl being probably the most famous, with the current single value of 35.453 being an average of 35Cl and 37Cl, the former isotope being about 3x more common than the latter.)
"According to Michael Berglund, a member of Iupac's Commission on Isotopic Abundances and Atomic Weights, which proposed the change, it is purely because more reliable and precise measurement data are now available. He points out that in its previous form, the standard atomic weight for an element like lithium was just an average value. 'It would actually be very difficult to find a material with this exact atomic weight,' he says"
Certainly a valid point.

I see potentially two issues down the road: 1) this is going to be extremely difficult for students (how can they calculate the MW of a molecule when the atomic values have a range? [*]), and 2) for our little world of polymers, the changes could be quite large simply because our molecules don't have a single digit quantities of any one atoms, but have immense amounts of them. As a somewhat extreme example, consider ultrahigh molecular weight PE. If I recall correctly, the molecular weight is about 4 million, meaning that there are about 290,000 carbon atoms and over half a million hydrogen atoms per molecule (4,000,000/14, the molecular weight of the methylene repeat unit). Changing the atomic mass value of either C or H by even as little as 1% will still result in a noticeable change in the molecular weight. End group analysis is going to be a lot more challenging.

And to really delight us, the changes are coming quickly:
The first ten elements for which atomic weights will be stated as intervals in the Table of Standard Atomic Weights are: hydrogen, lithium, boron, carbon, nitrogen, oxygen, silicon, sulfur, chlorine and thallium.
i.e., Let's try this out on the organikers first!

[*] And of course, we should always rearrange chemistry to please the students, right? But seriously, I'm just not sure how high school teachers will handle this.

Monday, December 20, 2010

Art & Rheology (Again) but no Puzzles This Time

Last week I posted about a rheological mystery that was presented as art. This week, I also found an artist, Jesse Higman, using resins but in this case, the carefully designed flow of the uncured materials is integral to creation of the art. The website of the artist is full of picture, but short on technical details, but the page devoted to the "Spiral" image shows how the canvas is meticulously distorted from a plane so that the resins flow in the desired shape. It's worth taking a little time to check out the page. Given the disability of the artist, the devotion to the picture (3 years work) is all the more exciting.

A second picture is labeled with "Rheology" on the page header, although I do not explicitly see the connection.

Friday, December 17, 2010

Thoughts on Transport Phenomenon

The article "Thermal Facts and Fairy Tales" [*] starts with a bang: "...a fixed temperature boundary condition in a thermal simulation represents an infinite heat sink." Fair enough. I always understood this, but have never seen it represented so succinctly. Having been educated as a chemical engineer, my thoughts immediately went back to my days hovered over a copy of BSL, aka Bird, Stewart and Lightfoot, aka the little red book "Transport Phenomena", which for decades was pretty much the only textbook on the subject used in undergraduate ChemE programs across the country. (Can anyone name a similar book in any subject that was so canonized?) A central tenet of the book was the similarity of heat, mass and momentum transfer.

So taking the opening statement and applying the basic concept in transport phenomenon to it, you can make the sentences "...a fixed concentration boundary condition...represents an infinite flux sink/source" and "...a fixed momentum boundary condition...represents an infinite stress sink/source", both of which I think are far more obvious than the original sentence.

[*] What am I doing reading "Electronics Cooling"? Well, I have done work for clients with heat transfer problems. The clients are mostly electrical engineering companies. I don't know if EE's are taught heat transfer at all (I suspect not) or they just don't pay attention in the class because they want to focus on circuits, antennas, IC's,... all the things that they went into electrical engineering to study - not heat transfer. You can infer the lack of understanding from the sentence quoted from the article. It only refers to a heat sink, even though the boundary could also be a heat source.

Thursday, December 16, 2010

PLA that acts like ABS

That's what Purac is claiming for a new PLA (polylactic acid). The trick to acheiving this performance leap is not the result of any additive or modification of the monomer by the addition of various moieties, but instead occurs at a more fundamental level: the polymer is a block copolymer of both the D- and L- stereoisomers. There is no mention of the level of blockiness in these polymers (are they di-block, tri-block,...?), but I imagine that the blocks are not able to co-crystallize and will instead phase separate and crystallize separately. I'm also not able to find anything suggesting that the D- monomer will also not be as biodegradable as the L- monomer is, but that should certainly be confirmed.
It's pleasing to see a simple change in monomers that can produce such a large change in a polymer. (And what about those people who thought that chemists couldn't do anything new with C, H, O and N? Heck, this didn't even need the N!)

Tuesday, December 14, 2010

Epoxy Resin Drop as Art - and Rheology Puzzler

Momoko Sudo is an artist who works in a variety of media, including colored epoxy resins. She has a blog that's a good starting point to explore her work. It's all abstract, so it may not be everyone's choice for art, although I certainly enjoy it. And maybe in the same way in which art and science are at opposite ends of a continuum, she calls the epoxy resin by the term "resin" while we would call them "epoxy".

The picture above captivated me, not only because of the colors, but also the wrinkles in the drop. (No idea what size the drop is.) I've seen piles of polymers before with similar surfaces, usually sitting at the end of an extruder that is undergoing a purge or such, where a steady stream of hot material is piled onto a cooling base. But this is supposed to be just epoxy, or more correctly, curing epoxy. How would it have gotten such wrinkles? Given the small drop size, I imagine any adiabatic build up of heat would be limited, so that the drop should be more or less isothermal, and so should the cure (there should be no oxygen inhibition in an epoxy either).

Any ideas? Not knowing any more than what I see in the picture, I'm baffled. It appears that this drop has flowed, but how could it have?

Will the Supreme Court become Probabilistic?

If this case gets acccepted by the US Supreme Court, it is going to be awful, just awful. A Guaitanamo detainee is appealing his case on the basis that the previous rule was wrongfully made using arguments of conditional probabilities. Keep in mind that this is the very same Supreme Court (well, Kagen is new, but the other 8 are the same) that previously stated 2 + 2 = 5, so how are they going to understand probabilities, their proper use and potential for abuse?

Monday, December 13, 2010

Career Advice

A reader of this blog, a student graduating soon, recently asked me for some career advice. Given the active discussion this week in neighboring blogs on the job situation for chemists, I decided to repost the email, slightly modified so as to protect the privacy of the individual and also fixing spelling/grammatical errors. The tackifier footnote isn't technically correct in all the details, but is fine given the context of the present situation.

My career advice is based on three principles: 1) focusing on the fundamental science in any situation 2) keep learning everything you can about ALL AREAS of science (the divisions of physics, chemistry, biology, metallurgy... are all man made and nature ignores them), and 3) be flexible – as was said by Robert Heinlein: "A human being should be able to change a diaper, plan an invasion, butcher a hog, conn a ship, design a building, write a sonnet, balance accounts, build a wall, set a bone, comfort the dying, take orders, give orders, cooperate, act alone, solve equations, analyze a new problem, pitch manure, program a computer, cook a tasty meal, fight efficiently, die gallantly. Specialization is for insects."

I’ve moved around throughout my entire career. In brief: 1 year @ Hercules (BOPP film), 11 years @ 3M (broken down as 5 years in pressure-sensitive adhesives, 2 years in EKG electrodes, 4 years in microbiology products), 1 year @ Conwed Plastics (PP netting), 1 year at Envoy Medical (implantable hearing aids) and 6 years @ Aspen Research (everything under the sun). There is a polymer thread throughout it all, and I was able to make it work by focusing on the fundamentals of polymers in all cases and not worrying about the jargon of any particular industry. For example, if you understand how a tackifier changes the rheology of an adhesive, then you won’t be confused when you discover that adding too much tackifier actually decreases the tack of an adhesive, despite it being called a “tackifier” [*]. I’ve seen people just baffled by that concept because they keep thinking that it’s a tackifier and it should keep making things tacky.

I’d say start in a big company if possible, as they will have resources (equipment, libraries and experts) that you cannot find anywhere else. Also, a big company will allow you to move around internally without major disruptions. Going to a small company is a whole different world as they lack equipment, libraries and experts. This can be overcome, as you can outsource testing and manufacturing, libraries are online and experts (old colleagues) are just a phone call away. Oops, make that a text away (I’m showing my age). Since you already know what can be done by large companies, you are not limited in what you can do at a small company. It just is a little more complicated. Also, instead of being say 1 of 10,000 employees, you are now 1 of 50. When you do well, everybody sees and knows it. (Conversely, when you screw up, everybody sees and knows it.)

Going into management is not something I can give any advice on, other than be aware that it is a 1-way street. If you leave the bench, you can’t go back. There will always be some newly laid-off employee who was working at the bench just last week – how can you expect to compete with that?

[*] In case you are not familiar with tackifiers and rheology, tackifiers are low MW materials with a fairly high Tg. They lower the plateau modulus of the adhesive, thus making it tackier, but at the same time of course, raise the Tg. Since most adhesive bases have such low Tg’s, you can raise the Tg some and there are no problems. But too much tackifier raises the Tg too close to RT and then you start losing the tack.

Slip-Sliding Away

While you may first think that this will be an entry about the massive snow storm that struck town on Saturday (even when it is light and fluffy, 17.1 official inches of snow is a lot of snow - the fifth largest snowfall on record and enough to collapse the roof of the Metrodome (video) [*]), this is actually about wall slip occurring at the solid boundaries of flow fields.

Richard Buscall has a letter to the editor published in the latest Journal of Rheology (subscription required or pay-per-view) that made a salient point or two regarding slip. My favorite quote was regarding the use of roughened or serrated tools in rheometers.
The author once heard somebody accused of neglecting slip say 'Yes, I am aware of the possibility of slip but did not want to compromise the accuracy with which the gap was set and quantified.' Now, one can be sure that that person did not actually mean 'I was prepared to risk the possibility of an error of unknown and therefore arbitrarily large magnitude in order to avoid the uncertainty in the gap setting of, perhaps, 1%'. Except that is what their assertion amounted to."
I always love the way the British are able to insult in such an incisive manner.

[*] Even though we all know that it was Brett Farve who did it just because he wanted another day to recover from his injuries.

Friday, December 10, 2010

The Impact of Biology on Polymers

I'm very excited about what new polymers we will be able to make in the not too distant future. Not because chemists are devising new monomers, but because biologists are. I wrote yesterday about isosorbide and how a new polycarbonate can be made with it. Today's post is about a new polyester.

The basis for these materials are a genetically modified strain of yeast (Candida tropicalis) which is able to take normal fatty acid and pin a hydroxy group on the end of the saturated chain. The picture below is from the articles abstract where all the "X"'s in the diagram are existing biochemical reactions that needed to be stopped in order to have the desired output, and the only way to stop them was by genetic modification, no small feat I'm sure. You can certainly read the article (paid subscription) if you want, but the rest of my post is on what I see happening with the newly created w-hydroxy fatty acid.

The easiest reaction I can imagine would be for the material to create a self-condensing polyester - a head-to-tail combination that much like normal PET production produces water. What sets this reaction about is that normal PET is made from two monomers - ethylene glycol and terephthalic acid, while this could be made from just the single monomer. Depending on the length of the saturated carbons, you could imagine crystallinity developing to a certain extent. It could also be worthwhile to investigate the biodegradability of the new materials, as a shorter version of these, polyhydroxybutyrates are known to have this property. You also could also try reacting it with one or more additional diols to create a random copolyester.

I have no idea as to the economics of scaling up production of the these monomers - I certainly have some doubts just because it is new, but still, this post and yesterday's post should have you convinced that polymer chemistry will be undergoing a revolution at some point in the not-too-distant future. New materials with new properties, courtesy of some microbial life modified to meet our needs.

Thursday, December 09, 2010

Isosorbide as a BPA replacement

One of the big corn processors from here in the Midwest is suggesting that isosorbide could be used as a replacement for bisphenol A (BPA) monomer in polycarbonates and epoxies and anything else that uses this versatile chemical. While it certainly can be used in place of the monomer-that-has-fallen-into-political-incorrectness, it will not be a drop-in replacement. This can be seen by simple inspection of the chemical structures.

BPA:Isosorbide:There are a couple of key structural differences. First, the overall length between the two hydroxy groups is much larger in BPA than in isosorbide (keeping in mind that the drawings above from Wikipedia are not on the same scale). That means that the comonomers are going to be much closer than in a BPA based system, and will make up a larger volume than before. Second, the stiffness of the central structure is greatly different, in that the phenyl rings in the BPA have some ability to rotate around the central carbon, while the center part of the isosorbide is going to be pretty much as still as a snowboard. Tg will undoubtedly be affected. Also note that isosorbide has more oxygens available for hydrogen bonding, another potential influence on Tg.

Let me be clear on what I am saying: the two monomers will produce different polymers. Not that different is inherently bad. The new polycarbonates produced with isosorbide can and will have very useful properties, but they will be different than those of standard polycarbonate.

If I was looking to replace BPA with another monomer, I'd keep in simple and look at the rest of the bisphenol family. Bisphenol E

and bisphenol F
would be a good starting point to cause the least disruption to existing polymers. You can see that the methyl groups on the central carbon are replaced by one or two hydrogens. The overall length of the molecule remains the same. I'm not sure that enough is known about the exact mechanism of endocrine disruption to dissuade the use of either replacement monomer.

Wednesday, December 08, 2010

Bone Cements

Reports are starting to appear of a new bone cement. The reports are all complimentary in that the material is an injectable fluid that quickly sets. However, these reports overlook one key issue and that is the thermodynamics of the reaction, specifically is there an exotherm and how large is it?

I worked briefly with bone cements while with my last employer (Envoy Medical), where we were using the cements to attach the implanted device to the various bones in the middle ear. We looked at a wide range of chemistries, and had several that, like this new material, were liquids and set very quickly but they provided excessive amounts of heat - not a good thing to have against living tissue. While this new chemistry looks exciting, I am curious about the exotherm that it generates. Any reaction that occurs quickly will generate all its heat quickly which is never appropriate for implantation.

Tuesday, December 07, 2010

Which is more Dangerous? Plastics or Tobacco

Apparently, the Indian Supreme Court believes plastics are. They have outlawed the use of plastic pouches to package gutkha, a type of tobacco clearly associated with various oral cancers.

The cynical side of me notes that gutkha is taxed, but as far as I can tell, plastic pouches are not.

Monday, December 06, 2010

A Very Minor Milestone

Sometime over the weekend, visitor # 10,000 [*] came by. As you can see from the log, it was someone (or something?) from MIT.
10,000 visitors in a little over a year. What's the next big mark, 100,000? Depending on whether the numbers take a linear or exponential growth, that could take 1 - 5 years. Or it may never happen. A linear growth pattern would reflect the continued poor quality of the writing and that the blog is merely taking up more space, while the exponential writing would also indicate that the writing is no better, only that more people are finding it and passing it along to others as "here's what you don't want to do".

[*] This number isn't very accurate as I started the counter only last October and the blog goes back a number of years before that, albeit with much less vim and vigor. It is also totally blind to anyone using a reader to follow this blog and those people would certainly be the most regular readers of the blog. So there are no "lucky customer" prized for being #10,000.

Only in California...

...would officials burn a house filled with explosives. I'm not going to go into the details, The Chem Blog covers them quite well. I would strongly suggest reading that entry. The short story is that police found a house with an unknown quantity of explosives and other chemicals in it. Rather than remove them, they plan to torch the place. Seriously.

They are taking precautionary steps like oh, say, evacuating 200 homes, shutting down the nearby freeway, installing firewalls... but still, doesn't this strike you as a wee bit insane? They have no idea what all is in the house, so why does burning it seem like such a great idea? They have no idea what they will be burning and releasing into the environment.

I can guarentee that the media circus of California will be watching the whole episode from helicopters, planes and the ground, and video will certianly be widely circulated when the day of the bonfire comes. And others will be monitoring the air for whatever is released, sure to incite hysteria. This will be fun to watch, but I'm glad I'm almost 2000 miles away.

Friday, December 03, 2010

Reviewing a Paper - Round 2

I review a fair number of papers [*] for the Royal Society of Chemistry, but this last week something new happened: I had a paper returned to me for a second review. I originally had been critical of the paper, somewhat for what was done, and somewhat for the way it was presented (quite sloppily with mistakes you would expect from an undergrad taking a lab class). I've been critical of papers before when reviewing them and never have really followed up on what happened to them (I've been meaning to, but it's not a top priority). I figure either the editor ignored my feedback or the authors went elsewhere with it.

So you can see that I was pretty amazed to get a paper back with an attachment showing the comments that I had originally made and their responses to them. They agreed with all them and made the appropriate changes. I figured this was the way it was suppose to work, but I've not seen it yet. So now I'm excited because I can see that I actually made a difference. How cool is that?

[*] What's a "fair number"? I probably average about 1 a month, although that actual event - "1 a month" never occurs. They always come in groups of 2 or 3 followed by longer periods of inactivity. I have no idea how 12/year compares to other reviewers. I suspect some do more, some do less.

Bridgestone Cutting Rubber Usage

Just this headline is eyecatching: Bridgestone to Halve Rubber Use by 2020. Overlooking the obvious solution of cutting sales in half, Bridgestone clearly has developed a significant new technology here and plan to take full advantage of it. The article does not hint at what it is; I'd be quite curious to know.

Thursday, December 02, 2010

Think It's Obvious? Prove It.

As promised back in October, the US Patent Office now is opening select patents applications up to the general public to comment on. And lucky us in the polymer community, the first one in organic chemistry is from IBM and it is for monomers that can be used to make polycarbonates, polyureas, polyurethanes...

How many times have you read a patent is said "that is so obvious" or "that is already being" done? (Please don't reply. If everyone did, it would crash the servor for weeks.) So here's your chance to change that. Register on the site and serve up some existing documentation to shoot this thing down - if you can. I haven't really looked at it in enough detail to make a decision about it for myself yet.

Wednesday, December 01, 2010

My Personal Kryptonite

I feel fortunate that the various aromas, fragrances and odors that are given off by chemicals never seem to bother me much. Whether its mercaptans,pretty much anything with a nitrogen in it...whatever, there is very little causes problems. But I was reminded yesterday of one solvent that will quickly have me leaving an area if I get even a small with - ether. That's right, diethyl ether.

A bunch of us were playing around with some nitrocellulose that was dispersed in ether. Out of the 6 of us, 1 was the only one that got light-headed and bolted. I wasn't even the closest person to the sample. And I also had a very strong emotion come rushing in from long ago and far away.

When I was 5, I was hospitalized with pneumonia for 10 days. That may seem like a horrible case, but keep in mind that at that time, women routinely stayed in the hospital for a full week (or more) after giving birth, quite a bit different from the 2 days maximum that insurance companies currently cover. Regardless, that whiff of ether immediately brought me back to those days in the hospital. I don't know why, as I wasn't operated on - maybe a nurse used some to get an antsy 5-year old to fall asleep.

It been said that the sense of smell is the most emotional of the senses, and this certainly provides evidence of that. I very seldom think about that time in the hospital, but that shot of ether brought it all back and with some other emotions that are hard to describe.

I'm fortunate that I never have had to do an ether extraction. That would be something for me to hand off to someone else, or find another extracting agent. But if you ever want to either 1) get me out of the lab or 2) just quickly know me out, a faint fume of ether will do.