Thursday, March 31, 2011

Recycling Symbol Confusion

Plastics News has an article this week about confusion over the numbered recycling codes that are used on many plastic items, such as you see over on the right. To me, the codes are very simple and easy to understand, but reading the article is enough to make my head spin. Apparently I have an overly simplistic view of the world.

The article is more or less a laundry list of findings in a recent survey; I find it impossible to summarize the results succinctly. Part of the challenge is that the survey included many different groups - recyclers, consumers, government officials, consultants...and since recycling is strictly a local effort, the results vary greatly. So consider some of these results:
  • "77 percent said that they get phone calls and emails from people saying they don’t understand the codes."(???? Somehow these people are smart enough to dial numbers on a phone but don't understand numbers on a bottle????)
  • "74 percent said the codes are used today primarily for education and that they want the codes to be strengthened so that they can be better used for that purpose." (Education? What kind of education can a person get from the bottom of a bottle?)
  • "40 percent said that the chasing arrows should be removed (Why?), with others suggesting that the recycling arrows only be used on items that can be recycled" (That is impractical since what can be recycled varies across the country)
  • "One-third recommended that a code be added for the type of molding method used to make the plastic" (Again, why?)
This could end up being even worse, since the ASTM is thinking about expanding the number of codes to include PLA and other plastics.

I really like what I have in my hometown. The recycling bin is a mixed bin. Everything - plastics, papers, cardboard, glass - all goes in it. I assume that only some of it is recycled, but the balance is then taken and burned to produce electricity. Pretty simple huh?

Wednesday, March 30, 2011

The Great Pallet Wars

A brief mention: The Wall Street Journal had an article a few days back about the ongoing battle between two groups of pallet manufacturers: those making them with the traditional wood, and those making them with plastic. It's a quick read.

Somehow the author missed out that wood-polymer composite (WPC) pallets also exist. I suppose a two-sided battle is easier to describe.

The Dance of Dew on a Spider's Web

Courtesy of the Soft Matter blog, a new open access (until April 20th) report on the clinging behavior of drops on a wire is worth looking at. We've all seen such drops, whether they are on spiderwebs, the strands of a dandelion gone to seed, or elsewhere. Looking closely at them, sometimes the drops are below the fiber and sometimes they surround the fiber.The authors not only are able theorize about what make these differences occur (contact angle and drop volume), but they are able to reproduce them and quickly, reproducibly change them by controlling the electrical potential of the wire.A dynamic setup like this is crying for movies and the authors don't disappoint. The images and movies are simply fascinating, especially the movies. Take a quick look even if this isn't really an area that you specialize in (I don't!).

As an aside, the paper itself is a very rough read, quite condensed, but very informative. It really looks to me that the authors initially submitted it to Science (or Nature), had it rejected, and then submitted it elsewhere without a rewrite. Too bad, I think this would have been a fine article for either of those two journals.

ANTEC 2011 - I'll be closing the place down

Ah, Spring in Minnesota, time when an old polymer engineer's thoughts turn to ANTEC. I'm a little disappointed that my upcoming talk at ANTEC (Boston) will be at 3:30 on Wednesday, May 5 4, the last day of the conference. Hopefully someone will still be there besides the cleaning crews looking at their watches. It could be worse; I could be talking at 4:30. Anyway, here's the title and abstract of the talk:
Preparation of a UV-Cured, UV-Absorbing Coating "Creating UV-cured coating containing UV-absorbing materials is akin to getting a suntan while wearing sunscreen. Despite this contradiction, we did just that. Motivated by concerns over CO2 emissions and economics, we sought to replace a solvent-based, UV-absorbing coating with an equivalent UV-cured formulation. This was ultimately achieved through creative formulation efforts. Besides being solvent-free and non-flammable, the coating is processed on equipment with a significantly smaller footprint than the older equipment. An additional unexpected benefit of the new formulation was that the viscosity was significantly lower. This allowed for a significant reduction in coat weight, further reducing the overall costs."
If any readers make it there, please introduce yourselves; I'd love to meet some of you in person. My typical modus operandi is to talk for 20 minutes, take questions at the podium for 5 minutes, and then leave the room to talk further just outside the room. I find this works well as many people don't want to ask questions in the large room (I can imagine many legitimate reasons for this). It's also possible that Aspen will be taping the internal practice sessions and posting them on YouTube like we've done in the past. Consider them as bootleg tapes!

Update: The talk is on the 4th!

Tuesday, March 29, 2011

SuperGlue Inventor Passes Away

Harry Coover, the inventor of SuperGlue (i.e., cyanoacrylate adhesives) has passed away. The LA Times article does a very good job with describing the man, the invention and its myriad uses.

I wrote a few entries about cyanoacrylates back in January. [1] and [2]

On Overhead Projectors and Transparencies

As much as everyone hates PowerPoint, maybe we need to step back and realize that it might have some value. Consider these two examples.

I ran across this statement the other day
"He [Kurt Symanzik] used hand-written slides for an overhead projector (which were the industry standard at the time for technical presentations). However, he obviously wrote out his slides with lined paper underneath as a guide, using every line. So he ended up with over 25 lines of equations and text per page. His handwriting was typical German: undecipherable, at least to Americans, looking like endless up-down-up-down-up-down. The clincher, though, was when an equation on one page referred to an equation on another. He'd slap the second slide on top of the first, off-set the two by half a line and point to both."

And then there was the prof that I had for my partial differential equations class in grad school at Illinois. He would carry his own overhead projector into the class despite their already being one there. His projector was special - it had two handcranked rollers, one at the top of the projection glass and one at the bottom, with a continuous roll of transparency film . (You can see where this is going, huh?). He'd start out writing by hand the lecture, which wasn't a problem. The issues arose when he started referring back to earlier parts of the lecture, cranking the roll back and forth as needed, sometimes really getting wound up and going back to something that was written in a previous lecture. After a few minutes of this (questions only made the whole matter worse), everyone was hopelessly lost. Needless to say, I did not do well in the class. (A few well-placed drops of cyanoacrylate adhesive could have solved the problem, but there would have been no way that I would have not been ROFL clearly implicating myself.)

Sure, PowerPoint can be abused and badly mishandled, but whatever I've seen is but a misdemeanor compared to these overhead transparency capital offenses. By the way, check out the PowerPoint suggestions over at ChemBark. As he says, they'll make you a lot less annoying.

Monday, March 28, 2011

Shocking, but not Really

Plastics News is reporting that two stalwarts of the plastics publishing industry, "Injection Molding" and "Modern Plastics" are shutting down their print editions, moving to an online only option.

As the headline states, this is both shocking to me, but at the same time, not really so. This is just another step in the reformation of media [*].

While I am glad to see that an online format will still exist, I am fearful. The problem that have so far with other magazines that have gone to an electronic format is that they are still stuck in a print outlook. I'm sure you've seen the ones where the online images are flayed out just like a printed magazine, and they even have cute little graphic that makes it look like your turning a physical page over. The whole effort takes so long to load up that I just don't bother with it, whereas with a print magazine, I would more or less flip through every page to see if any catches my eye. At most with the new formats, I will look at the table of contents and then very specifically go to just an article of interest.

So to the publishers, if you are reading this (and I am sure you are), do this changeover right. DO NOT make the online magazine look like a physical magazine that takes far too long to load. Make it look like a webpage, with links that load quickly, maybe the TOC on the left-hand side so I can jump around, whatever. There are plenty of people with creative imaginations that can make this fantastic. But if you go with the standard fall back, you will lose me as a reader of what I normally consider required reading.

[*] Commonly called the decline of journalism or some such moniker. I see it as a shift to a new form; I'm just not sure what. Consider that the New York Times is going back to a limited-free access form, and that local newspapers are still thriving (by local, I don't mean the major news paper that covers an entire metro area, but the really small, weekly papers that cover very small parts of it), the role of the internet on print media has not be completely played out just yet.

Thank You, Chubby Checker

I'm rushing back from a client meeting to get started on other work, enter the rheology lab to hang up my coat (yes, it is still Winter here in Minnesota), and three people are already in the lab staring at the rheometer - two girls, ages about 8 and 10 [1] [2], and the head of sales. The girls are the new VP's daughters, they want to know what the dynamic mechanical analyzer does, and the sales guy is spouting his usual BS about how I'm a world class expert in the matter [3].

I've complained before about the difficulty of trying to explain rheology to most people, even those with a technical background. It's really tough and I don't think the situation will improve in the coming decades. (Look at the videos that are linked on the left-hand side of the blog for an hour-long tiny little introduction to the subject.) All told, there are really good reasons that it's a graduate level subject.

An 8- and 10-year old? Quick John, you gotta think fast or you will lose them. They ain't going to wait for me to hem and haw, and they certainly won't understand any mathematical description.

"It's like dancing," I said, "an old dance called the twist". They smile. "You start twisting your hips and then we see how much your shoulders move." At this point, the sales guy jumps in [4], and starts talking about how we also see who's leading and who's following. The girls are happy, twisting and make for the door. I'm relieved and am grateful for my appreciation of older music.

[1] The summer interns around here look younger and younger every year.
[2] No, we don't hire interns that young. There are child labor laws around here.
[3] Don't even try and tell me that your sales people are any better.
[4] A long time ago in a galaxy far, far away, he worked as a chemist. He still thinks he's a chemist. Come on, he's gone over to the dark side. Was Darth Vader still considered a Jedi Knight?

Thursday, March 24, 2011


Shrinkage is a constant battle in polymers. In thermoplastics, molten plastic always has a lower density than the corresponding solid, thereby guaranteeing shrinkage as the part cools (molded, extruder or whatever). With thermosets and other reactive systems, shrinkage also occurs but as the result of a changes in the separation between molecules. Prior to reacting, the molecules are attracted to each other by van der Waals forces. The attraction is relatively weak and so the distances are relatively large. Once reacted, the molecules are covalently bonded and kept at a distance that is much shorter than the van der Waals forces kept them. The result is again shrinkage, all the more so if the heat was needed to initiate the reaction.

One way to minimize the shrinkage in a reactive system is to use monomers that polymerize through ring opening. In such a system, the formation of the covalent bond along the backbone of the resulting polymer is somewhat canceled by the covalent bond broken in opening the ring.

This then raises the question: if breaking one ring is good, would breaking two rings be even better? The answer is yes, but a monomer with two independent rings won't do the job. Instead, the two rings have to have a common element, so as this monomer, a spiro-orthocarbonate:Spiro-orthoesters and other similar materials can also be used, basically anything where multiple rings are joined at a single point. Polymers prepared from these monomers can show no shrinkage and in some cases, even expansion upon polymerization. In the polymerization, the two rings in the center of the molecule are broken at the same time, while only one covalent bond is formed during the polymerization. The net result is that one of the short covalent bonds is replaced by a van der Waals bond - hence the expansion.

This technology was first realized back in the 1970's, and despite some active patenting, I am not aware of any commercialization. I imagine that the monomers are too expensive to be useful in most applications.

Wednesday, March 23, 2011


It's always bugged me that the two polymer abbreviations in the title exist. The E stands for ethylene, the VA for vinyl acetate. The abbreviations above are for the (random) copolymers of the two. I'm not 100% sure, but I believe that the two monomers can be copolymerized in almost any ratio (100% polyethylene exists, 100% polyvinyl acetate exists, and lots of grades in the middle exist so I would be surprised if there really was an intermediate value that couldn't be made).

Any way, getting back to the abbreviations, the only difference in the two is whether the copolymer has more than 50% vinyl acetate. If it does, go with the VAE, otherwise stick with the EVA. Strange and rather arbitrary.

I'd love to see someone proposing the similar name change for say, ABS (a terpolymer of acrylonitrile, butadiene and styrene), constantly renaming it depending on the relative amounts of A, B and S. Whoever would suggest such a system would already be starting in a hole since there typically is more styrene in the material than acrylonitrile or butadiene. But think of the possibilities: we could have 6 options:
  • ABS
  • ASB
  • BAS
  • BSA
  • SAB
  • SBA
Or consider ASA plastic, a terpolymer similar to the ABS with one of the A's standing for acrylate. How could you possibly tell the difference when there are two A's?

EPDM (ethylene, propopylene, diene - don't ask about the M) could also face a name change to PEDM (at least the D is consistently in last place).

Anyone proposing such a crazy scheme would probably be tarred-and-feathered (wood tar of course, since we want to biosource it!) so why do we tolerate it for EVA/VAE? Personally, I prefer EVA - it just rolls off the tongue so much better than VAE.

Tuesday, March 22, 2011

A Tale of Two Chemistries

From the Dow Corning website
"Did you know ... Outside of the petroleum industry, Dow Corning Corporation maintains the largest distillation operation in the world!"
which is more proof that the organic chemical industry, including the polymer industry, are deeply indebted to the petroleum industry. Silicone is the second most common element in the earth's crust - obtaining the raw material is easy as going to a nearby sandpit. After a few reactions, distillation and more reactions, you have silicone polymers for $10/lb and more.

Compare this to organic chemicals whose raw material are obtained from the bottom of a well, in some cases the top of the well is several thousand feet beneath the ocean surface. Such wells cost millions to drill, and this is all just to get the raw material. Add in some reactions, multiple distillations and more reactions and you come up with the starting materials for organic chemistry which cost just a few bucks a pound. Just keep in mind that in most cases, the starting materials that we desire so much are waste products from the refinery which is pretty much interested in producing alkanes of very high purity [*]. Quite the contrast, huh?

[*] The purity of course, is focused not so much on separating heptane from octane, but in separating heptene from heptane, etc...

Strange Physics in the Banking World

I've remarked in the past about the abuse of scientific terms by certain professions, such as microbiologists thinking that multiplication and division are the same.

I ran across a new example yesterday in the novel "Victory" by Joseph Conrad.
"The Tropical Belt Coal Company went into liquidation. The world of finance is a mysterious world in which, incredible as the fact may appear, evaporation precedes liquidation. First the capital evaporates, and then the company goes into liquidation."

Monday, March 21, 2011

Rock Star Jobs for Polymers?

In a weekend discussion, it came up that for people working in computer animation, everyone wants to get into a few select companies such as Pixar or Dreamworks. Not only is that true for people in the industry itself, but also the general public understands the appeal.

Contrast that with the plastics and chemical industry. Is there a group of elite companies that everyone wants to get into? I'm thinking far more than just the big ones like the Duponts, ExxonMobil, BASF... I'm wondering about companies with that "rock star" quality. And then if you throw in the additional requirement that the general public also understands the appeal, I think the list is pretty much down to zero. About the only place I can think of might be NASA, but even that is questionable these days. (NASA back in the 60's and 70's? Now that would have been a whole different situation!)

Friday, March 18, 2011

Mental Models

Fellow blogger Derek Lowe, a pharma chemist, has an interesting post about the mental models that he carries around in his head for drugs interacting with proteins. He even mentions sounds, which goes a lot further than I do. Take a look at it, as even with all the medicinal applications, there still are some fun ideas.

What's my model for polymers? Probably similar to yours, but I keep tacking on new aspects over time. Everyone has the long chain. Without that, you're not a polymer person - it's that simple. Go long or don't go at all.

But here's some of my additions and why they are there. First, the chain is always moving. Whether from Brownian motion or stress relaxation, it's always on the go. Even with an end (or two!) tethered to a surface, it's wriggling like an earthworm. Or maybe the snake pit that Indiana Jones despised so much.Even in solids, you still have localized motions of the crankshaft type, all of which are needed to explain diffusion of water or oxygen through packaging materials. These additions were added when I started studying rheology.

Another addition are defects. These are a little harder to imagine in great details because the nature of it varies greatly from one polymer to another. Some examples
  • chain ends and the gaps they create
  • endgroups
  • improperly incorporated monomer in the chain (such as head-to-head addition instead of head-to-tail)
  • incorporation of the catalyst, initiators, ...
  • crystal defects, and
  • tie molecules in semi-crystalline polymers
These defects are usually ignored or downplayed, but in my mind they are critical. As the saying goes, a chain is only as strong as its weakest link. These defects are the weakest link. Theoretically, HDPE should rival diamond in its modulus, but it never does and that is because of defects. As was discussed back in November, defects were proposed as the initiation site for degradative oxidation (a big reason that I think that the proposal has legs). And I am sure that defects are the source of this patternthat Duke researcher found occurring when polymer breakdown upon exposure to high voltage. If a polymer were a continuous and pure substance, it would be tough to force an initial break, but with defects always present, initiation is much easier. These ideas were an early addition to my model, when my dissertation involved crystallization of HDPE, tie molecules...

I'm sure there are other additions, but they are comparatively minor. Please feel free to suggest what you carry around, as new additions can be good.

Wednesday, March 16, 2011

A Very Strange Monomer...and Polymer

Here's a report of a chemical that was used in a most unusual way. Look at the starting material was a modified form of a dye called rylene: (The brackets in the picture even suggests that this monomer is a polymer itself, although they are in fact used to indicate that the number of naphthalene groups can vary a small amount.)

The rylene was modified by the addition of phenyl triflurovinyl ether groups, as you can see in the graphical abstract:
Now take a close look at the red circle on the right - the alkenes form a cyclobutane linkage, a very strange unit for building a polymer with. Give the high strain in the ring, you can't get very long chains as the odds are too great that one of them will give way in the process of building the chain. That makes the polymerization all the more impressive. Just don't look for this one on the market anytime soon.

Tuesday, March 15, 2011

Don't Tell the Society of Rheology...

If they ever find out about this, they will revoke my recently renewed membership and permanently ban me from ever being reinstated.

Glam rockers: (the band Sweet)

GLaMM rheology:[*]Glam rock didn't last too long (arguably, it lasted too long). Here's hoping that GlaMM rheology will last longer and be more useful.

[*] Graham, R. S., A. E. Likhtman, T. C. B. McLeish, and S. Milner, “Microscopic theory of linear, entangled polymer chains under rapid deformation including chain stretch and convective constraint release,” J. Rheol. 47, 1171–1200 2003.

Wednesday, March 09, 2011

The Changing Definitions of "Thixotropy"

Science is a very conservative effort, as we seldom can completely toss out what we've found in the past to be true. Instead we have to keep adding and modifying our understanding, constantly improving it. Consequently, it goes against the grain to have definitions of words changing. It's difficult enough to get a consistent definition in the first place (despite the efforts of IUPAC and other standard creating organizations), so to see subtle changes occur over time [*] is disconcerting.

Such is the case with the term "thixotropy". As has been reported in a review paper (open access) by Barnes, the term was first used nearly 100 years ago to describe the situation with certain gels that would become liquidlike when shaken or otherwise disturbed. Upon being allowed to rest, the gel would be restored. (At a molecular level, what was occurring was that the gel network responsible for the solid characteristics was disrupted and/or destroyed by the mechanical forces. At rest, the network would restore itself.)

Somewhere along the lines, a more proper, less operational definition has arisen, which is that a thixotropic material is one where the viscosity of the material at a constant stress rate decreases over time. It certain captures the original definition, but is broader in that it is not restricted to gels.

It also is unfortunately the rheological term term that I personally think is the most abused. The confusion of the term's meaning that I've encountered is endless. First, there are the people who confuse it with shear thinning (a.k.a. pseudoplasticity), a term which instead refers to the viscosity decrease seen when the shear rate increases. This is totally different than thixotropy, as a shear thinning material at a constant shear rate will have a constant viscosity over time. The decrease in viscosity only occurs when increasing the shear rate.

Second, there are the people that think it has something to do with thickening, since "thick" sounds like "thix-". This problem is compounded by all the "thick" gels created by adding a thixotropic agent; and of course these gels show thixotropic behavior.

Clearly rheology would be better off when sticking to the most current definition, but there is quite a bit of embedded infrastructure that needs to be replaced, and the characteristic time for that reaction is that of an engineer's career. Just remember that for exponential decay, the characteristic time is the time for a 63% reduction from the original concentration, a value that seems fairly correct for this situation.

[*] Now on the other hand, I find etymology - how the definition of words change over time - to be a fascinating study. I love that languages are alive, constantly changing entities, with English probably being the most vibrant of all.

Monday, March 07, 2011

"Estrogen Activity in Plastics" Report Has Many Flaws

The experimental details and conclusions from the report that all plastics having estrogen-mimicking extracts is filled with experimental errors and erroneous conclusions.

First off, some of the test methods were ridiculous. The samples were stressed in UV light "by placing samples about two feet from a 254nm fluorescent fixture for 24 hours, simulating repeated UV stress by sunlight (e.g., water bottles) or UV sterilizers (e.g., baby bottles and medical items)" and by heat in an "autoclave (heat and moisture stress) by autoclaving at 134°C for 8 minutes, simulating moist heat stress in an automatic dishwasher".

Long-time reader of this blog know that that 254 nm may make a good jungle test, but it does not simulate sunlight. The results of this stressing need to be correlated to the real world or they are invalid. Would we be surprised that extracts are at higher than normal level?

The same is true of the autoclave exposure - maybe even more so. No dishwasher gets anywhere close to 134 oC - all the PE containers would be hopeless deformed. Again, would we be surprised that extracts are at a higher than normal level?

The authors lake make the unsupported assertion that all these mimics can be avoided. As support, the authors [*] have prepared samples that do not show estrogen-mimicking activity. Unfortunately, the details of the formulations are not disclosed. How can this get published? Can you go into the lab and reproduce these results? Isn't that the hallmark of a scientific publication? Furthermore, these samples were never tested for anything beyond their estrogen-activity (EA), as if that is the only concern that an engineer has when developing a food/beverage package.

But it gets worse when they then overplay their hand and draw this conclusion:
"Because additives comprise a small fraction (typically 0.1-1% by weight) of plastic resins and compounds, and because plastic resins and compounds using EA-free additives are processed during manufacture in a nearly identical manner as conventional resins and compounds containing chemicals with EA, the replacement of additives having EA with EA-free additives should have very little impact on the cost of the final product. Furthermore, EA-free additives have only a slightly higher or no additional cost compared to additives with EA, so that their cost impact is very small or non-existent."
Not only are the conclusions not supported by the data, but the logic is filled with non sequitors. This all based on the word "should", as if that mere wish will make this come true. Anybody who thinks that the word "should" can be used to predict behavior is someone without real world experience. "Should" tells you how the world isn't, not how it is. "Should" won't get you FDA approval, EPA clearance, pay the bills, or keep the lights on. "Should" can get you a patent and a published article if the reviewers aren't following too closely.

Let's see these resins being used in real-world products, not just in manufacturing samples. Something that has to withstand the distribution and production cycles, something that has to meet clarity requirements, cycle times, and all the other expectations that consumers have.

And one last bit of advice on the business end: don't go around calling your materials as EA-free. As test methods become more sensitive, you may find that they aren't EA-free. Analytical chemists never say that something is "_____-free", only that it may be there below the detection limit. It's just a bit more sloppy science in a large pile.

[*] 4 of the 5 authors work for either of 2 companies, Plastipure and Certichem, companies owned by the last-listed author. The companies stated goals are to "focus on developing safe plastic materials and products" and to "provide highly sensitive & very reliable in vitro cell proliferation assays for detecting hormonal activity" respectively. Too bad this journal doesn't require a "conflict of interest" statement so that others are aware of this, keeping in mind that apparent conflicts of interest don't invalidate research.

Updated. The conflict of interest is noted in the research paper.

Friday, March 04, 2011

Good News on the BPA Front

The battle against bisphenol A (BPA) has been going on for some time. The concern is not about it being toxic, but rather that it is an estrogen mimic, causing a cascade of reactions in the human body leading to a wide range of symptom and diseases.

Now comes a new report that many people are taking as a disaster: even BPA free plastics such as polyethylene, polypropylene, polystyrene and others have their own set of estrogen mimics.

I have my own take on this report: it is great news. Since these estogens mimics are everywhere, there is no longer any need to focus on polycarbonate and BPA. Either focus on eliminating all plastics from the world, or ignore the issue. There is no in-between.

This very much mimics what critics of the BPA-as-an-estrogen-mimic-is-causing-massive-heart-problems arguments have been saying: estrogen mimics are already everywhere in our food supply, not as an additive or because of contact with plastics, but because they are inherent to the food itself. Tofu (and any other soy product)is probably the worst, but they are also found in various grains, beans and even beer. Estrogen mimics are a fact of life, not just 21st-century life. They cannot be avoided, so can we get past this?

More Thoughts on "Materials Science"

A few followup comments to yesterday's spleen venting against "materials science". While I do think that the three fields should be separated with specialists in each, there is a good deal of overlap between them. Consider these examples:
  1. Terminology: The term "plastics" used to describe a large large segment of polymers has its origins in metallurgy. "Plastic" deformation is a permanent deformation of a material resulting from high stresses, and the "plastics" that are such much a part of the modern world show this behavior quite readily. Similarly, "annealing" was first used in treating metals, but the term has been borrowed by the plastics industry as well.
  2. Processing: Many of the processes used in these fields are common to each each, and the number is growing more each year. Consider the latest reports about blow molding metals, recalling that injection molding of metals is already old hat.
  3. Fundamental Science: At a more fundamental level, there is plenty of overlap of the concepts of thermodynamics, rheology, chemical bonding etc.
As much as I stress the divisions between the different sciences, I also know that the differences are arbitrary and man-made [*] and that nature offers incredible treasures to those willing to play at the edge of each field. There are no cliffs at the edge that will the death of anyone playing too near, but instead are hidden glades of beauty for anyone willing to explore.

Just be sure you have a good footing in one of the fields. Generalists never get any of the good stuff.

[*] Not only made by Man, but also by men.

Thursday, March 03, 2011

On the term "Materials Science"

I have to admit I hate the term "materials science" (and consequently, "materials scientist") and have for a long time [1]. At face value, it is an overly broad term including the fields of metallurgy, ceramics, polymers and maybe even a few other odds and ends such as semiconductors (kinda cool how I just marginalized the $300 billion semiconductor industry, huh?). I don't have a problem with any of these fields, but I do have a problem with someone somehow thinking that they can be combined, and worse yet, mastered by an individual. I've met people who have specialized in these fields - they certainly do not come anywhere close to knowing everything that they can and should know about their fields, let alone have much more than a very basic understanding of any of the other fields let alone all three. [2]

I tend to avoid spending much time looking at material science journals just because there are so many articles that I really have no interest in. That percentage is already high enough for a journal devoted to polymers; why look at journals that are guaranteed to increase the percentage?

The strangest use of the term material science is in industry, where you see it used in job titles, only I've very seldom ever seen a job with that title where they truly sought a full-blown across-the-board material scientist. The positions always seems to be aimed at a subset. In my experience, usually polymers. (I certainly recognize that as a personal bias.)

In my last employment position, I did truly work as a "materials scientist". This was a small medical start-up that did not have the funding to hire the three people that they really needed. (The device did have metals, ceramics and polymers.) I admit I did a bang up job with the polymers, but really was hurting with the ceramics and the metals. If someone really could handle all three subjects, I would be greatly impressed.

[1] I received by Bachelor's degree from the University of Minnesota's Department of Chemical Engineer and Material Science. Yes, the two areas were combined and still are to this day.
[2] I certainly fit that description, but then, that isn't saying much, is it?

Wednesday, March 02, 2011

Nonlinearity in Rheology - Be Afraid, Be Very Afraid

The impact of "nonlinearity" across the sciences is, well, nonlinear. If a chromotographer tells you your sample has a nonlinear calibration curve, tell him "boo hoo", rub your fingers together to indicate your playing the world's smallest violin and continue on. It simply means that he will have to work a little harder to put error bars on the analysis, rather than being able to apply a single % across the range.

But when the rheologist tells you that your sample is being tested in the nonlinear response range, run and don't ever come back. It isn't the rheologist that is complaining as nonlinear behavior in polymers is far more interesting.

To explain all of what is known of nonlinear rheology here would be impossible, so let me give you a small taste. For small enough deformations of your sample, the actual value of the deformation doesn't really matter much - you'll get the same output regardless of what the deformation is. All you really need to know is the stress and the strain rate. But if the deformation becomes too large, then everything - the strain, the strain history, the strain rate, and the strain rate history - and they are all interrelated by tensors whose manipulation becomes extremely complex if you're not using Cartesian coordinates.

But as I said, it's the nonlinear behavior that gives rheology all it's magic, such as the normal forces that we see in die swell and rod climbing.

Tuesday, March 01, 2011

A Crack Smoking Poodle

As I mentioned back in October, the US Supreme Court took on a case of about whether freebase cocaine is the same as crack cocaine. The difference is quite important as crack cocaine has prison sentences 100x worse than for cocaine powder.

The case was heard yesterday,and...well... I hate to suggest it, but it looks like Justice Breyer may have tested some of the evidence in the case. Consider this line from the official transcript(page 34, line 25 - page 35, line 3):
"People sniff it often, I guess, if it's a salt. And that's bad. And then there's a kind that's worse, that's freebase or crack, and that isn't a salt and it isn't a poodle and it isn't an acid."(emphasis added)
In all honesty, the poodle first made his appearance back on page 28, line 10, but even given that, Justice Breyer's comments still had the strong stench of a non sequitor. The overall discussion was much more a matter of semantics and grammar than a legal or chemical discussion, emphasizing how difficult it can be to do a great job in writing legislation.