Friday, December 30, 2011

Mt. Stupid

From Saturday Morning Breakfast Cartoon on December 28, 2011 (Note that this particular comic is safe for work, but that is not always the case with SMBC):
Here's hoping that 2012 finds us all climbing the ultimate steep slope on the right hand side and never interacting with anyone living on Mount Stupid.

And with that, I'll be taking a few days off of well-earned vacation now that our corporate move is winding down.

Thursday, December 29, 2011

A Bullet to the Head

There was a report earlier this year of a Chinese man that had had bullet lodged in his brain for 23 years, but now the New England Journal of Medicine has a report that trumps that - a Russian man with a bullet lodge in his brain for 82 years! Take a look:
According to the doctors,
"The patient revealed that at the age of 3 he had been accidentally shot with a pistol by his older brother. The bullet had struck him just inferior to the nose, and he had lost consciousness for several hours, recovering completely without specific therapy. In his adult life, he had achieved professional success as an engineer, even winning the Soviet State Prize for his accomplishments."
82 years is a record unlikely to be broken. Isn't it strange that he was shot and that no medical evaluation was even made at that time?

PEO Crystals - The Snowflakes of Polymers

While polymer single crystals have always showed a myriad of shapes, articles on the crystallization of polyethylene oxide (PEO) has always been the most exciting to read. That polymer, more than any other is able to crystallize into a seemingly endless variety of forms depending on reaction conditions. This is largely because of the flexibility of the ether linkages in the backbone. There is minimal hindrance to axial rotations and so getting some type of crystal to form is pretty much a given. It's just that no two crystals seem to be the same, much like snowflakes. Consider these 8 examples:

The above AFM photograph comes from a research letter (open access) published in the new ACS journal Macro Letters. As with all crystallization, you have the competing effects of nucleation and growth occurring. The relative rates determine the shape of the final crystal. Working through a wide range of supercooling conditions and molecular weights, the researchers were able to create a "morphology" diagram - a map of what conditions will lead to what outcomes. Here's a look at it:
where the letters in this figure corresponds to the different morphs in the previous diagram. The general trends is that as the supercooling (or molecular weight) increases, the fiberous nature of the crystals increases as well.

It's a short article with lots more detail in it - I highly recommend reading it if you have an interest in polymer crystallization.

ResearchBlogging.orgZhang, G., Zhai, X., Ma, Z., Jin, L., Zheng, P., Wang, W., Cheng, S., & Lotz, B. (2011). Morphology Diagram of Single-Layer Crystal Patterns in Supercooled Poly(ethylene oxide) Ultrathin Films: Understanding Macromolecular Effect of Crystal Pattern Formation and Selection ACS Macro Letters, 217-221 DOI: 10.1021/mz2001109

Wednesday, December 28, 2011

Chemistry vs. Physics &. Biology

Of the three physical sciences listed above, physics and biology seem to have a lot in common, with chemistry being the odd-man out.
  • Physics and biology both have "dissident" scientists who disagree with some of the key fundamentals in the science. You don't have to spend too much time in physics forums to run across people who think that all of quantum mechanics and/or relativity is wrong, and that they have a better explanation that doesn't require ideas that clash with our everyday experiences. Biologists have to deal with all the people, including scientists, who deny evolution. Fortunately, chemistry seems to be immune to "dissident" thought. I can't think of a single example where a fundamental chemical idea is challenged.
  • Physics and biology have both done a better job of selling themselves to the general public than chemistry has. Physicists are able to get funding for particle accelerators that may not ever be able to produce results applicable to the "real world", and yet many in the general public are well aware of the search for the Higgs Boson. Astrophysicists are similarly able to get funding for ever larger telescopes and space telescopes. As long as they produce the occasional breathtaking picture of nebula and galaxies, the general public is happy. As for biologists, they were able to get billions for sequencing the human genome, although they at least held out the promise of "personalized medicine" and the discovery of the gene that causes disease X, Y and Z (with the soon to follow cure for these diseases). Has there ever been a large scale chemistry project, let alone one that captured the public's imagination? I can't think of any.
  • Chemistry seems to more feared by the public than physics or biology is. I'll admit that this is a personal perception that might be heavily tainted by my experiences, but it seems to me that there is more chemophobia than there is fear of anything that physicists or biologist work with. Certainly there is fear of radiation and certain microbiological organisms, but these fears are limited to rather thin facets of life - nuclear power plants & weapons for physics, and food safety & infections/disease for biologists, whereas chemophobia can exist with practically everything that people touch in their lives. If a physicist is working with optics, that's o.k. If a biologist is working with fish, that's o.k. [*] If a chemist is working at all, it's with chemicals and that's bad no matter what.
While I am glad that we don't have to deal with the crackpots, it sure would be nice to have a few large-scale projects that the public is all to happy to pay for, one that will improve their perception of chemistry and reduce the amount of chemophobia in the world today.

[*]as long as they are not genetically modified fish. (I realize this is a small concern in the US and a bigger concern in Europe.)

Tuesday, December 27, 2011

The Two Sides of Plastic Man

Throughout history, "Plastic Man" has taken many forms. The oldest version is the comic book graphic novel hero. Being plastic, he was able to assume a vast array of shapes such as
or even this
All this fame and glory earned him a spot on US postal stamps back in 2006:
and apparently even had his own Saturday morning cartoon show in 1979
(I never saw it - at that point I was too deep into upperclassman chemical engineering classes to watch TV.)

But,like all Superheroes, "Plastic Man" had his dark side, as can be seen in this video from Sonny [*] and Cher from 1968:

The Kinks also had their own song "Plastic Man" the following year with entirely different music and lyrics (that Heaven for small favors), but equally disparaging: 
From Superhero to Superzero - the life of Plastic Man

[*] This man went on to be come the Mayor of Palm Springs and then later, a US Congressman, believe it or not.

Wednesday, December 21, 2011

Aspen Research has Left the Building

Yesterday the last truck arrived with all the goodies from our old building. We are now officially moved and located at our lovely new building, 8401 Jefferson Highway in Maple Grove, Minnesota. Having left the city of White Bear Lake, we no longer have to explain that we are so far north that we have white bears. "Maple Grove" is just another generic suburban name that needs no explanation (Wikipedia lists over a dozen cities in the US and Canada with the name. I've never seen a disambigulation page listing further diambigulations, have you?) Now it's just a matter of hooking everything back up, reclaiming the chair and desks and file cabinets and ... that others are squatting on, and away we go. The computer network is fine (YES!), the offices are nicely finished (the nicest cubicles I've ever seen) and significantly bigger than what we had before. How small were our old cubicles you say? Let's just say that Aspen Research was a leading the charge on nanotechnology 20 years ago.

With the whole operation of unpacking everything and putting it all in new places, you do get to look at all the stuff anew and rediscover some things, decide other things are no longer worth keeping and yet other items are going to be dealt with differently than before. It's all good.

Tuesday, December 20, 2011

Not Hiring Someone You Should Have

When a decision is being made to hire a new employee, I see 4 potential outcomes based on two factors. The first is obviously whether or not to hire the person, and the other is whether or not the person should be hired. A simple diagram of this situation is this:
The people in the upper left hand corner we all know about - the ones who got hired and are working out well, and the same goes for the lower left corner - the ones who got hired and are not working out well [*]. The right hand side of the chart however, is more of a mystery. When a decision made to not hire someone, there is no feedback. Very seldom do you ever find out if you made the correct decision or not.

This discussion however, was all made on the basis of a single person making the decision or equivalently, an entire team being in agreement on the decision. If that is not the case, then it is possible for some people to explore more of the right hand side of the box. I can recall one case where I recommended against hiring an individual, the manager did it anyway and it turned out to be the correct move. Through that, I was able to explore some of the upper right hand corner, although it was just me and not my manager. While it is good, that's one of those situations that can really haunt you, that you would have let someone good get away. I never have claimed to have great insight on hiring, and that case certainly proved it.

[*] It's been my experience that large corporations have a very difficult time getting rid of these people, which is why I called that box a "really bad decision". Even if the person is ultimately let go or leaves on their own, it still is wasted time and effort for all involved.

Monday, December 19, 2011

The Supreme Leader's Contributions to Polymer Science & Engineering

With the passing of North Korea's Supreme Leader Kim Jong Il, I thought that we should review the many contributions that the master of all trades gave to the field of polymer science. After all, anyone who can shoot 38-under par (including 5 aces) in his first time on a golf course, write 6 operas in two years and personally design the Juche Tower
certainly must have made immense contributions to polymer science.

Sure enough, he did. A quick search for with the terms "Kim Jong Il" and "plastics" yields a treasure trove of results, although you first have to get past all the articles about his son having plastic surgery so as to look more like his grandfather. But here's some paydirt - the Supreme Leader in an undated photo touring a plastics factory:
A press release from just a few months ago further elaborates the man's involvement with the Raknang Plastic Goods Factory:
"He set forth the tasks to be implemented by the factory.

An important duty facing the factory is to produce more plastic goods conducive to improving the standard of people's living in reliance on the existing production foundation and bring their quality to the highest level, he said, and went on:

It is necessary to direct great efforts to the technical control and the management of equipment and, at the same time, steadily raise the level of technical skill of the producers.

When making a product, it is essential to produce goods liked by people, products impeccable on any market and having world competitive power and increase their varieties to meet different demands and taste of customers."
Extremely insightful, wouldn't you say? We can all learn from this great man. I am sure as well that he was able to provide pointers for removing mold lines and addressing the blush issues that keep creeping up from time to time (such as increasing the cooling water temperature by 10 degrees).

But was this man limited to just knowledge of injection molding? Of course not - he was skilled in extrusion and fiber spinning too: Back in February, he toured a factory making vinalon, a fabric made from polyvinyl alcohol,
and the press reported:
"He expressed great satisfaction over the fact that the workers of the complex and their helpers have successfully wound up in a short span of time the huge project equivalent to the construction of a large chemical base by their own efforts and with their own technology in hearty response to the intention of the Party to develop the economy their own way and improve the people's standard of living by depending on the nation's economic foundation.

It is an astonishing miracle that the builders have constructed a precious structure of eternal value by their own efforts under so hard conditions by valiantly overcoming bottlenecks and difficulties lying in their way and dedicating their all to the project, he said. He extended high appreciation and thanks to them for having performed the laudable feats for the country and people."
(emphasis added).

Do you see that? Eternal value! Those of us outside of North Korea build machines that will last for a few decades at most before being discarded, but Kim Jong Il was able to devise machinery that would last forever. Truly this was the Supreme Leader. His only shortcoming was having a human body.

Friday, December 16, 2011

The Real Danger in Polycarbonate (it's not BPA!) and a Solution for it

Polycarbonate (PC) is taking a lot of heat in the popular press these days because of the BPA (bisphenol A) that remains in it as a residual monomer. BPA is an estrogen mimic, but isn't really a concern at the levels found in polycarbonate. Even if all the hysteria about BPA leaching out of PC is true, nobody is suggesting that BPA will kill you. But for PC, that is only half the story.

Polycarbonate is normally made by copolymerizing BPA and phosgene. Phosgene is the real bad guy that needs to be feared with all your being. Phosgene has a long track record of killing people, beginning in World War I when it was used as a chemical weapon, and it's potential use was feared in World War II [*]
While industrial accidents with phosgene have been relatively rare, they do occur. Some recent examples are a leak that led to the death of a DuPont worker last year in West Virginia, and leaks in Thailand and China that in both cases also had a death, along with hundreds of injuries. BPA never did this to anyone.

But not content to continue living with these problems, that creative bunch of people known as polymer chemists (Ouch! Sorry, I twisted my arm patting myself on the back) have devised phosgene-free routes to prepare PC, typically using diphenylcarbonate (DPC) as a replacement for the phosgene. BPA is still in the picture, but the DPC is a much safer option than phosgene. Shell Chemical has been a large driver in this effort and is building a pilot plant in Singapore to supply this material. The DPC is made in part with carbon monoxide which is nowhere near as toxic as phosgene.

It's also interesting to note that despite the economic downturn and all the people avoiding PC like an elephants avoiding mice, PC production is still growing at 4 - 5% a year.

[*] Phosgene is a great example of something being quite deadly but not having a wretched smell.

Wednesday, December 14, 2011

Isolating Thixotropy from Shear Thinning

With non-Newtonian fluids, the viscosity is no longer constant. Depending on the flow conditions (and the material of course), the viscosity will decrease as the shear rate increases (shear thinning) or it will increase (shear thickening). In some cases as well, there is a time dependency - the viscosity at a given flow condition can decrease over time (thixotropy) or increase (rheopexy).

What I've just describer however, are ideal models that don't exist in reality. As far as I am aware, a purely shear-thinning material does not exist. Sure, most thermoplastics do show shear-thinning behavior, but it is over a range of shear rates, rather than ALL shear rates. (At low shear rates, the viscosity becomes constant and is given the name of zero-shear viscosity, and a some materials will also show a constant, high shear rate viscosity). The same is true for shear thickening materials - such behavior is observed over a range of shear rates and not in other subranges. And it becomes a bigger mess when time-dependent behavior is added. I've never seen a thixotropic material that wasn't also shear-thinning.

It would be a great help for educational purposes if we could find such materials that show only these isolated ideals of non-Newtonian behavior, particularly with the time dependent phenomenon. I think all educators have students that struggle with the difference between shear-thinning and thixotropy. A material showing only thixotropic behavior would be a great aid in demonstrating the difference.

Lastly, there is one set of fluids I am aware of that are able to isolate one subset of non-Newtonian behavior and those are Boger fluids - they have a constant viscosity like a Newtonian liquid, but show large amounts of elasticity.

Tuesday, December 13, 2011

A Derivation of the Cox-Merz Rule

For reasons I've never understood, the most common search term that consistently, year-in, year-out brings people to this blog is "Cox-Merz rule" or some variation thereof. So I'm going to add fuel to the fire with some new research results about this important rheological relationship.

The Cox-Merz rule is a empirical observation that h( \dot \gamma ) = h*(w) when  \dot \gamma = w.

The importance of this is that it allows a tremendous amount of lab work to have significance in non-lab (production) settings. In the lab, viscosity is normally measured by imposing sinusoidal stresses or strains on a sample and observing the mechanical response. Sharp observers will question how a sinusoidal deformation can be useful in a production setting which has unidirectional flow (or something close to it). The Cox-Merz rule is able to jump that gap - as long as the magnitude of the oscillatory frequency matches the magnitude of the steady-state shear rate, then the viscosities will be the same. This was first observed empirically and holds for many many materials, thus greatly simplifying the equipment and time spent in the lab.

But once one learns of the rule, the questions then arise as to when it won't work. Again, empirical observations have shown to be cautious with "networky" type materials such as filled polymers or systems with complex hydrogen bonding for example.

David Mead has a fine magnum opus published in Rheologica Acta (free access until the end of the year!) in which he is able to derive the Cox-Merz rule for polydisperse materials. This has been previous done for the idealistic case of monodisperse polymers, so this is a real advancement. The kicker however, is the last line in the article (actually, the last line in the Appendix):
"The Cox-Merz rule is effectively a 'suspicious' coincidence' based on identical dimensionless frequency transitions and correct asymptotic scaling behavior rather than anything predicated on fundamental polymer physics."
All this work and our basics thoughts aren't changed.

Mead, D. (2011). Analytic derivation of the Cox–Merz rule using the MLD “toy” model for polydisperse linear polymers Rheologica Acta, 50 (9-10), 837-866 DOI: 10.1007/s00397-011-0550-5

Monday, December 12, 2011

The Future is Clear

Two new research articles were recently published, both of which have a common theme: taking objects that are normally opaque and (through the magic of chemistry) making them translucent. Both materials are made up a (more or less) continuous matrix which enclose open spaces. However, the approaches to translucency differ and make this an interesting comparison.

The first object to become clear is a crab shell (original article ($), review (free)), which involves immersing a (dead) crab into a serious of baths - HCl, NaOH and ethanol to remove the minerals, proteins, fats and pigments and leaving just the chitin behind. The chitin is then "clarified" after acrylic monomers are injected and reacted. Here's a picture from the abstract of the starting material, after the three baths, and then the final product.
The "clarification" that occurs in the last step occurs is the removal of scattering sites because the refractive index of the acrylic and the chitin are similar. Absent the acrylic, the air that filled the opening left by after the other materials were washed out in the baths was different enough in refractive index to cause scattering.

The second object that is clarified is an open-celled glassy, foam (original article ($), review article (free)). The preparation technique is completely different - a polyurethane sponge is used as a template, into which nanoparticles of silica are added, the pH is adjusted, and then the urethane is burned out leaving the clear glass foam behind. Nanoparticles are generally too small to scatter light, so even with the difference in refractive index between the silica and the air, clarity is maintained.

I'm not sure if this is the start of a trend that we will see more of, but it might very well be since transparency is generally considered "good" and increase visibility (and not just in science as transparency in government and financial institutions are both highly desired). A rheologist that I knew from an earlier portion of my career had replaced the covers on the twin towers of his Rheometrics RDA rheometer with acrylic so that all the electronics inside could be visible. It was quite a bit more interesting to look at than the normal beige - I'm just not sure that any real purpose was served.

Wednesday, December 07, 2011

Still Moving

Posting has been slow, especially compared to the number of boxes I've been filling this week.

For those who missed the post last week, Aspen Research is on the move to a new, bigger-and-better location. But is all comes at a price. Mr. Client, we won't be running your sample this week.

In the process, we've all learned a few things.
  • Nothing gets chemists to stop bench work and start packing like shutting down their hoods.
  • A hydraulic lift table
    is fabulous for sliding heavy lab equipment off the bench and then onto a pallet. Don't move without one.
  • I need to go through all the papers I've collected over the years and toss some of them. At the same time, some of them definitely need to be reread (and blogged about).
  • Everybody is all wrong about zombies. When they are wandering about, they are NOT looking for "Brains!", but internet connectivity. When we lose ours on Friday PM, you're going to see 42 lost people wandering around with their computers looking for "Internets!" If we were to become zombies, why would you expect us to behave any different?
After a week of this effort, we are making headway. Stuff is disappearing from the staging areas and into trucks faster than it is being replaced. People are starting to straddle between the two buildings. Off we go.

Friday, December 02, 2011

The Teacher Can Make All the Difference

Quite a few years ago, I worked for a large corporation that had a high school "internship" program (for lack of a better word). The program was limited to students from the larger core city, not the suburbs (so it was a community outreach program as well). The program consisted of a weekly set of 2-hour "lectures" from January until June, followed by employment during the summer in various labs around the company. The lectures were taught by company employees about a wide range of technical subjects. I gave two talks about polymers and enjoyed it tremendously as it was a great bunch of kids to be working with.

I realized before starting this effort however, that I had to make it interesting, which meant only enough math and theory to clarify concepts, and lots and lots of time in the lab playing with all the craziest non-Newtonian materials I could devise. I had examples of rheopexy (cornstarch/water), the Wissenberg effect (rod climbing), Slime (PVOH/borax/water), Pluronic gels that thickened up heating and liquified upon cooling...Their homework assignment between the two lectures was to find non-Newtonian materials in their homes which they did reasonably well at [*]. And knowing that if I'm not excited about the subject, they wouldn't be, I put as much energy into the talks as possible, portraying how exciting polymer science can be.

The reviews came back at the end of the semester and my jaw hit the floor. The students thought I had done a great job, in fact they consistently ranked me as the second best teacher. It's just that "the cement guy" was better! CEMENT?!?! I never got a chance to talk to that guy, but if he could make cement even more exciting than polymers, I tip my hat to him, and say "the teacher can make all the difference".

[*] My favorite discussion item for a non-Newtonian material at home is toothpaste - a Bingham fluid, but it has to be discussed "properly". To do so, I would set the scene by getting them to think about being in the bathroom. I would then slowly lower myself into an armless chair, pull out some reading material and talk about a material that you need to apply a certain minimal stress to get it moving. Not enough stress and it would pop back in, but with enough stress, things would move along smoothly. It wouldn't take too long before you would see some smiles and smirks and they finally realized what I was talking about - toothpaste! (What were you thinking?)

Thursday, December 01, 2011

Moving - A Lab's Ultimate Nightmare?

The calendar now says December, a month we have long dreaded here at Aspen Research. Normally we get the year end rush of people trying to get things done before the end of the year while they still have the money in the budget, but this year is entirely different. We are moving across town to a new location.

I've never moved a lab before. When I worked for a megacorporation, my wife's division had to move their lab to another building, but that was move from one lab building to another lab building. Things like hoods and benches were left behind and were already in place at the new location. This is entirely different. We are taking it ALL with us: extruders (and all of their auxillary equipment), benches, hoods, sinks... pretty much everything except for the lingering aromas of the many thiols I work with.

Why the move? Expansion. The new building is twice the size of this one and we will need it all very quickly.

In some ways, the sale of Aspen Research from Andersen Corporation back in February was a practice run, even if very little physically moved. As part of the sale, we needed to divorce ourselves from all the shared IT resources (not just internet and computers, but accounting, HR...), so we've been there and done that fairly recently, and in this day and age, quickly and efficiently moving and reestablishing IT resources is everything. Fortunately email addresses don't change, cell phone numbers don't change and the desk number (which are changing) will be rolled over automatically for a year.

Hopefully Santa Clause will still find us in the new location. There is this capillary rheometer [*] that I really want and I've been a good boy all year...

[*] "...with a compass in the stock and a thing that tells time..." and no, I'm not going to shoot my eye out.

Wednesday, November 30, 2011

Nylon Offgassing Ethylene

Polish researchers have published a letter in Biotechniques discussing ethylene emissions from nylon. Doesn't that strike you as odd?

This emission is important to the researchers and other people performing plant research as ethylene is well known as a plant hormone (and it is effective at the parts-per-billion level or less), so if you are sprouting seeds on a nylon membrane (as is commonly done) and the membrane is outgassing ethylene, then you potentially have a problem.

I'm stuck on trying to identify the source of the ethylene in the nylon however. Nylon, whether through ring-opening polymerization (as in nylon 6) or as copolymerized (as in nylon 6,6) is not made from ethylene, and the extrusion/pelletization of the nylon should heat the material enough to degas any ethylene that is there for whatever reason. The exact nature of the nylon is unknown - it is only identified as "Whatman, Nytran N, 0,45 µm". The Whatman webpage mentions a couple of items that deepen the mystery: the nylon has a positive charge, and that the membrane is cast. Given all this, I see three possible sources of the mysterious ethylene:
  1. Does the process of charging the nylon introduce the ethylene?
  2. Do the solvents used in the casting process contain any ethylene?
  3. Lastly, I wonder if the source of the ethylene is something as simple as the membranes being slipped into a polyethylene bag as a primary package when they are shipped. The membrane could absorb ethylene outgassing from the bag.
Any other ideas?

Tuesday, November 29, 2011

A Polymer with Reversible CHEMICAL Crosslinks

One bit of research (Science Magazine, subscription required) that had a lot of discussion (here and here) this past week or so has been the development of a "thermoset" plastic that can be heated and allowed to flow as a thermoplastic does.

I do think the research is interesting and should prove to be quite useful in the future, but what I really dislike is all the hype that these reflow characteristics are so unique and novel - they are not. Styrenic block copolymers and other thermoplastic elastomers show this behavior all the time - they are nondeformable materials at room temperature, but when you heat them up, they become liquids that can be shaped to any form you desire. The materials are made up of blocks of two different polymers along the same chain. At room temperature, the blocks phase separate and form physical crosslinks that prevent deformation. Upon heating, the physical crosslinks soften and allow the material to flow.

What is novel in the latest research is that the crosslinks are chemical, not physical. Heat reversibly breaks up the crosslinks, while cooling restores them. That's a neat trick that I've not seen before and is certainly worth the discussion. It's just that the thermomechanical behavior isn't novel.

Monday, November 28, 2011

Strawman Arguments

Everyone knows that you shouldn't compare apples to oranges, but then why can some people compare two items that are even more dissimilar and publish it as innovative research? That's what happened over the weekend, when researchers from the University of Sheffield compared silkworm silk to high density polyethylene (HDPE) (subscription required)(here is a open access review), and Surprise! Surprise! found that the silkworm is more efficient at polymer processing.

What a dreadful comparison. Chemically the two materials are entirely different - silk is a multiphase polyamide while the HDPE is a polyolefin. Moreover, the two materials aren't processed at the same temperatures, and yet this allows the researchers to win a strawman argument by showing that the silkworm is more energy efficient since it doesn't need heat and/or high shear to produce orientation in the silk.

Why didn't they compare a natural polyamide to a synthetic polyamide? Synthetic polyamides can be made at room temperature:
and you don't even have to look closely at the the synthetic strand to see that volumetric production rate for the synthetic polymer is more greater than for a silkworm.

A further fault in the comparison that the researchers made was that the silk is solvent spun (from water) while the HDPE used in this example was not (even though HDPE can be gel spun at room temperature).

While the mechanical properties of silkworm silk are different (tougher) than those of synthetic nylon, not necessarily better. Depending on what your design requirements are, tougher may not be desired at all.

And lastly, while silk does have a unique set of properties that scientists cannot yet match in one material, keep in mind that the silkworm was been developing their materials for millions of years while synthetic polymers have only been in existence for less than a century.

Why the researchers chose to overlook all these facts is beyond me. Surely they can't be that desperate for a publication that that they need to stoop this low for it.

Wednesday, November 23, 2011


I'm out of the office for the rest of the week (thanks to the miracles of modern technology, this post was typed up last week and is only appearing today) enjoying time with family and a turkey (the kind you eat, not the type of person you avoid). Posting will resume again on Monday, November 28th.

Tuesday, November 22, 2011

The Big Picture on Transportation Fuels

Materials Today has a nice short article (open access) about the world energy system. and transportation in particular. I would make it required reading for engineers, environmentalists, politicians, and voters [*]. The point of the article is that the world uses a tremendous amount of energy, and no matter how much you want to replace petroleum from that amount, viable options to replace that large amount of energy do not exist, at least at present.

How large is large? Well, from the get-go, the article asks you to think about energy in units of PJ (Petajoules, 1015 joules), and EJ (Exajoules, 1018 joules). The fact that these prefixes need to be explained because they are used so seldom indirectly indicates the magnitude of the problem. Also eye opening one of the equivalences they provide: a million tonnes of oil equivalent (Mtoe) is 41.9 PJ. The total primary energy supply last year was 514 EJ, so you can do the math. Simply put, we use tremendous amounts of oil, and while it will eventually run out, we'll be seeing plenty more of it the rest of our lives.

If you don't agree with that last statement, then read the rest of the article. The authors spend most of the article looking at the alternatives being used and proposed. None of them will come close to replacing what is needed. We can't grow our way out of this, or use bugs or algae on a large enough scale. The summary of the article is pretty clear cut and impossible to argue with:
"Transport fuels of the future will require numerous sources; there is no silver bullet."

[*] I'd also add political commentators and talk-show hosts, but does anybody here think it would do any good? People like that already know the answer; what's the question?

Monday, November 21, 2011

Throwing Away Books

I admit that I have always had a very hard time throwing away books. I've always loved books as long as I can remember and working in the local public library in high school furthered that love. Undergraduate education and then graduate school led to the acquisition of more books that I still refer to on a regular basis. Considering how much the Gutenberg press changed the world, and how governments have burned books in order to keep power, a book has always been too valuable to just trash, and so I've always found someone else to take the ones I have no longer wanted, with libraries being a favorite option. Strangely the librarians that I've known have either felt exactly as I have or been of the extreme opposite, being able to toss one without a second thought. I didn't have a problem with the library throwing it out, as the blood was on their hands and not mine.

I discovered this weekend however, that those feelings are beginning to change in me. I had no problem with tossing out a couple of old dictionaries and a thesaurus. I hadn't used them in years, relying instead on online dictionaries, and I can't imagine a library taking them for pretty much the same reason. (I'm keeping the Scrabble dictionary however, as that is an integral part of the game as much as the board and tiles are.) I still can't imagine tossing other books just yet, but suspect that that too will change in the future for me.

I've haven't yet picked up a Kindle/Nook/electronic book reader, but I know that at some point in the future, I will own electronic books. At the same time however, I don't think the attachment will be there. I anticipate being able to easy delete those kind of books, maybe because of the whole easy-come/easy-go syndrome, and as those books become more ubiquitous, I think it will lessen my attachment to paper books, much like internet dictionaries have done so with paper dictionaries. I find it strange that easy access to information in one format cheapens the information in other formats.

Friday, November 18, 2011

Marine Pollution

As I've mentioned before, plastic garbage has no business being in the ocean (or forests, fields, etc. for that matter). With rare exceptions [1], humans are to blame for releasing plastic into the environment. The plastic did not get up and run into the ocean all on it's own. As much as I hate posing dichotomies [2], in this case there are basically just two approaches to "solving" or preventing the problem. One approach is to ban plastics or at least some plastics, such as the bag bans occurring around the world. The other approach is to change human behavior so that humans prevent the release of the plastic into the "environment". What is somewhat strange about this dichotomy is that the two sides are not equal in effort. Bag bans are in the news constantly, but little is being done to change human behavior.

You see this uneven dichotomy in a wide range of other "problems". Guns for example, have one side attempting to ban them while little is done by the other side to prevent their use in crime. Drinking and driving is also being ever increasingly criminalized without an equal increase in preventing it.

The only example that I can think of where the forces are reversed is with matches. Here in the US, we have had a decades-long, public-ad campaign featuring a cartoon bear (Smokey the Bear) who's tagline is "only you can prevent forest fires".
No one is actively trying to ban matches - the focus is entirely on changing human behavior to prevent fires.

The effectiveness of Smokey's campaign (he and his message have extremely high recognition in the general public), efforts to change human behavior can be successful. So why aren't we doing this with plastic bags and other forms of plastic pollution?

I bring this up as both the Plastic New blog and the SPI blog, In the Hopper have recently discussed the marine pollution conference that occurred in Dubai. While I commend their efforts and desire for success, unless the programs are on the scale of a Smokey the Bear campaign, they will likely be too little to change anything.

[1] A variety of natural disasters can unintentionally introduce plastics into the environment, but these events are small and infrequent.

[2] Just 2 options for solving a problem? Only if you are uncreative.

An All Plastic Road Bridge

I've been wanting to write about Axion International for some time, ever since I saw a military tank driving across a plastic bridge that they made. And not just any plastic, but recycled plastic. That was back this summer if I recall correctly. But now Axion has announced that one of their bridges will be used on a public road here in the US. This may seem like a risky proposition, but as I already mentioned, the military has used these bridges as well as railroads, so automotive traffic should be a non-issue. The low maintenance issues will be a definite benefit in a northern state such as Maine (I'm assuming that they use salt on their roads in the wintertime as we do here in Minnesota).

The Axion International website multiple videos showing their bridges in action. Assuming that the product performs (no reason to be otherwise), the use of these bridges will only continue to grow.

Thursday, November 17, 2011

A boat that is completely solar powered

Monday's post was about yachting (albeit with LNG tankers), so keeping with the nautical theme is the cover story of the November 2011 issue of High Performance Composites. The picture itself if captivating:
That's right, it's a solar powered boat, with solar power being it's exclusive means of propulsion. At 31 meters long, 15 meters wide (and over 500 m2 of solar panels), it's not for your average owner, but still clearly illustrates the role that composites can play in lightweight, innovative design. The ship, christened Tûranor, "is circumnavigating the world with the message of sustainable ship power."

The irony of course, is that while the "power" (don't they really mean energy?) is "sustainable", none of the materials of construction are.

Wednesday, November 16, 2011

That's Teamwork

I received my latest issue of the Journal of Rheology yesterday as was taken aback by the last article in it - here's a scan of the first page:
I don't know if I've ever seen 7 authors from 5 different institutions before for a run-of-the-mill paper before. Sure there are the blockbuster papers such as those of the human genome, and the eventual papers on the Higgs boson, but this is just a 22-page long rheology paper.

Tuesday, November 15, 2011

A Great New Sensor to Detect Food Spoilage - It'll Never Make It

I spent a number of years at a past employment situation working on a product that most people think is a pretty good idea - a time-temperature indicator for perishable food. Simply put, it was a small label that would change color to indicate that the food had reached the end of its shelf life and should be disposed of. It was sensitive to both time and temperature, as both of these (and the interplay between the two) affect the quality of food - even properly refrigerated milk will eventually spoil [*]. Such a product is far better than the printed date codes that never change when a product is thermally abused.

While I do think that the product was a good idea, it's one of those products that will never see the light of day unless it is mandated by the government. Why? Well, follow the money.

Here in the US, groceries are a very low margin business, typically just a few percent. So even if a label costs just a few pennies, that will wipe out the profit margin of the grocer unless they raises their prices, and there is no way that one grocery store will do that if their rivals won't, especially on low end foods like milk and ground beef. Beyond that, food distribution in this country consists of the producer, a distributor, the grocer and the consumer. For a label such as this to be useful, everyone in the chain has to agree to participate in the game, otherwise no one can. While the largest grocer in the US (Walmart, yes, Walmart) may want the label, rest assured they will not pay for it and will be loathe to be stuck with the "shrinkage" that occurs if the label goes off in their stores. They will make sure to blame the expired label on the distributor or the producer or whoever else, and fights will quickly ensue.

The product that I helped develop underwent a gradual color change, which we thought was a good attribute. (Contrast the gradual color change with one that occurred suddenly: for any one in the food chain buying the product, it would just like playing Russian roulette). However, with the gradual color change, we knew that consumers would look through the products for better less-changed labels, much like they currently pick through product for better shelf-life dates.

Despite have very simple, robust technology that was inexpensive, (far better than any competitive products out there at the time or developed in the last 10 years since then), management could see that they product would never make it and so they killed the project.

I was reminded of all this when I saw this report late last week about an novel oxygen sensor that will tell when food, in this case, whole cuts of meat, should be tossed. While the physics and chemistry are different, the economics in the food industry are the same. Nobody will decide who will pay for the label and nobody will decide who will pay for the spoiled product. Sadly, I can state that this product is DOA.

[*] You are actually integrating k ti exp(Ea/ R Ti), where k is Arrhenius equation prefactor, ti is the ith temperature interval with corresponding temperature Ti, Ea is the activation energy and R is the gas constant. By the way, we did this integration using adhesive tape and sandpaper (Eat your heart out, MacGyver!)

Monday, November 14, 2011

An Extreme Connection between Fracking and America's Cup

The connection between America's Cup (that race held at irregular intervals to determine whether the US's millionaire sailors are better than those from around the world) and fracking, the technique of injecting fluids under pressing into gas-containing formations of rock to release the gas trapped within, may be difficult to see at first, but stick with me, this is a story unlike anything you have seen that will have you laughing by the end. Unless you already know the connection, there is no way you can imagine what I will tell you here.

The use of fracking to produce petroleum gases is growing in the US and around the world. Polymer producers - those making polyethylene(s) in particular - are quite excited about this as a good amount of ethane is mixed in with the methane. Being too high in fuel content to burn, the ethane is separated from the methane and sold to be polymerized (after conversion to ethylene of course). One of the larger formations in the US being fracked right now is the Marcellus shale formation which underlies large swaths of Pennsylvania, New York and West Virginia.

While plants are being built in the area to polymerize the ethylene made from the ethane, Sunoco wants to pipe the ethane through Philadelphia to the port, put in on Liquid Natural Gas tankers and float them to the Gulf coast for processing. But in order for this to occur, an Act of Congress was required. Not because of the risks associated with this option, but because of...well, I'll let the article directly explain the hoops that need to be thread and the cockamamie option that the US Congress took to solve the problem:
"... the LNG vessels that hold the supercooled liquid fuel in large spherical tanks now sail under foreign flags. A law known as the Jones Act requires that all ships carrying cargo between U.S. ports must be built, owned, crewed, and maintained by Americans. The ships Sunoco would charter are American owned and were built in the late 1970s in Massachusetts. But they were reflagged in the Marshall Islands in the 1990s. It requires an act of Congress to reflag the vessels as American, which would require them to use U.S. crews. [Senator] Toomey and Rep. Pat Meehan (R., Pa.) devised a novel way to reflag the tankers by including them in the America's Cup Act of 2011, special legislation that would permit 60 foreign vessels to participate in the America's Cup yacht race. The law is expected to receive final Senate approval and the president's signature this week, before the America's Cup race is scheduled to start Saturday in San Diego."

LNG tankers attempting to qualify for America's Cup? Can we really look forward to a ship such as this:

lining up against a ship such as this:

That would make for some lively TV coverage, wouldn't it? ("Oh no Jim, it looks like the catamaran got to close to the props of the tanker and that yacht is now flotsam for the fishes...")

Quite a connection, huh?

Friday, November 11, 2011

Flashing Labels

A long time ago in a state far, far away, I worked on making polypropylene (PP) films, some of which went into making labelstock. One of the films we made was white, the white coming from white minerals that were mixed in with the PP. It actually was a three layer composite with a calcium carbonate in the middle layer and TiO2 in the outer layers. (TiO2 is a more effective whitener than the CaCO3, but it costs more. The three layer approach let us economically make a very white label.) One problem that we would occasionally have in the product were "shiners", small little patches that were shiny, almost iridescent. If I still recall correctly, they were the result of moisture in the base resin. By themselves, I actually thought they were not bad looking - my wife suggested that we offer the material up as a winter or Christmas product since they could pass as snowflakes of a sort. I would have proposed that to the company if only we could control their production but unfortunately, we could not.

Any chance of going back to recreate that product is now dead, as PragmatIC Printing (yes, the company spells "pragmatic" just that way) has announced that they have incorporated printed ICs with light displays into BOPP (biaxially oriented PP) labels. (Sorry, there doesn't seem to be any video yet showing the prototypes.)

Flashing labels vs. labels with "shiners" on their surface? Given the Powerpoint presentations that I've we've all seen marketers put together incorporating every bit of animation and zing that Microsoft can imagine, I've got to believe the marketers will pick the former.

Birefringence in Polycarbonate

Highline Polycarbonate has the second of series about the internal optical properties of polycarbonate - birefringence, the stress-optic law, etc. The articles are very well written and I would recommend them to anyone working with glassy polymers, PC or otherwise.

The first article (you probably should read them in order) is is here while the second one is here. A third article is promised in the near future as well.

Thursday, November 10, 2011

Give me a photon! No, you better make it 2!

It's pretty well known that polymers (and all organic materials for that matter) can fall apart when they are exposed to UV light. The energy of the photons (E = hc/λ) is in the same order of magnitude of the energy needed to break the chemical bonds [1] and so the end result is not too surprising. In some rarer cases, visible light can do the job too on certain bonds, although this happens only with small organic molecules, not full-length polymers. Since visible light has less energy than UV, the bonds being broken are inherently weaker. Trying to build a polymer with such bonds in the backbone would be especially problematic, since with the high number of bonds in a polymer, the odds of one of them breaking (and thereby degrading the molecular weight of the polymer and corresponding mechanical properties) would be pretty high.

So the report of a polymer completely degrading upon exposure to near-IR light (with their even lower energy photons) can be an eye opener [2], unless you know what it really occurring behind the scenes. The trick is not for the bond to absorb one photon, but to simultaneously [3] absorb two of the photons. The total absorbed energy is now 2hc/λ, so if λ = 470 nm (barely in the near-IR), then the energy absorbed in the bond is the equivalent of a single 470/2 = 235 nm photon, and that's plenty energetic to degrade most organic bonds.

The challenge preventing widespread adoption of this technique is that the near-IR light of each individual beam is not strongly absorbed on its path thought the material, so the odds of having the two photons absorbed in the needed time interval is also unfortunately small. But with the challenge also arrives a tremendous processing advantage: with two-photon absorption, the degradation reactions can be localized to very small spaces if the two photon beams arrive at right angles to each other. Furthermore, this local reaction site can be deep within the material. The degradation occurs only at the intersection of the beams and not along their individual paths.

The advantages of using this approach(subscription required) in therapeutic situations should be pretty obvious, even if the specifics are quite worked out just yet.

[1] For instance, an aliphatic C-C bond has a bond energy of 347 kJ/mol, which corresponds to light of 344 nm, and a C-H bond has a bond energy of 414 kJ/mol, corresponding to light of 288 nm.
[2] A scientific blog that forgets to mention that this is two-photon absorption?
[3] "Simultaneously" is too restrictive of a term - the absorptions need to occur within a very small time interval that depends on a number of variables in the experiment.

Wednesday, November 09, 2011

Nigeria, a Net Exporter of Plastics

Plastemart is reporting that Nigeria has now become a net exporter of plastics. [*] This is no small feat as the country has the 31st largest economy in the world, and this is all just a result of the oil production. Petroleum contributes only 14% of the production in the country. More than anything, it represents the internal development of facilities to manufacture the plastic pellets and capture the added value in the product, rather than just selling the petroleum as a raw material.

All facts on the Nigerian economy were taken from Wikipedia

[*] It is not explicit in the article, but the focus appears to be about the resin pellets, as opposed to products made of plastic. If final products, packaging materials, adhesives and whatever else is made of plastic were considered in the trade balance, I have to believe that the net balance would be in the opposite direction.

Tuesday, November 08, 2011

Double Duty Additive for PVC

Most polymers are compounded with a small amount of functional additives to help their performance in certain, critical manners, such as antioxidants, UV absorbers, slip agents, antimicrobials, antifungals, etc, These are added in small amounts (generally less than 2 wt%) for two reasons. First, they are much more expensive than the base compounds, and secondly, they generally work so effectively that that only small amounts are needed. This two characteristics still don't prevent some people from pushing this too far and not adding enough of the additives (usually as a cost reduction effort [*] but that is another issue for another day.

Polyvinyl chloride (PVC) is nothing without additives, albeit the most common additives for PVC are plasticizers which added in much higher levels than noted above. But the other additives noted above are also commonly incorporated in PVC as needed. There is a new report out yesterday (subscription require) that some newly developed additives, amide derivatives of ethylene glycol-bis(2-aminoethylether)-N,N,N′,N′-tetraacetic acid, that were originally designed as antimicrobials, but were also found to have UV absoprtion properties as well. That is big. You now have one additive that can do the job of two. While UV absorbers are typically added at higher levels than antimicrobials, the use of this additive will decrease the amount of proper UV absorber that is needed, an approach that every processor can get behind.

[*] ...and even more usually combined with obtaining these additives from a low cost producer whose quality is also low

Monday, November 07, 2011

Termites Chewing On Plastic

I was quite surprised to learn this morning that termites can actually eat plastic, or maybe more properly, they can chew through it. Not just plastic film, but even polyethylene pipe. Why the termites decided going through the pipe rather than around the pipe is something that only a termite would understand (although those with a more comedic sense could start a whole string of "why did the termite go through the pipe" [*] jokes).

I live in a climate too far north to be ever have been concerned about termites (for my southern brother, well that is a different story as termite protection of his house is a way of life), so I only know the basics - that they can be destructive to wood. I can only imagine the surprise when people first started finding termites chewing through plastic pipes.

So in quick attempt to turn this lemon into lemonade, I ask the following questions:
  • Could this "biotechnology" be used to breakdown waste plastics? i.e., a low energy grinder.
  • Extending on this, could entomologists get varietals to only chew on certain plastics, thereby allowing for effective separation of mixed plastics. Start with a big pile of plastic over a screen, let the PET chewers in first and they breakdown all the PET which then falls through the mesh, then unleash the LDPE chewers...(Isn't it fun to tell other professionals what we think they should easily be able to accomplish?)
  • Can termites be used as a hardness tester for plastics? Or maybe an abrasion resistance test depending exactly on how the teeth of the critters interacts with the plastic?

[*] He just want to go with the flow. (Thank you very folks, you've been a wonderful audience I'll be in town all week be sure to try the brisket and tip your servers...)

Wednesday, November 02, 2011

First,you make up the data, then...

Isis the Scientist had a post yesterday (with lots of discussion) about in what order the various sections of a lab report should be written. Whatever. People, do what you want, just make sure that the final product is good. To me, the most important part of writing a report occurs before you start experimenting: it's the the time when you make up the data.

Yes, make up the data. Believe it or not, this was something I learned to do as an undergraduate engineering student, and the professors actually encouraged it.

Hear me out. The junior level chemical engineering lab was a royal pain in the posterior. It was long, it involved larger pieces of equipment than any of us had ever worked with and we were given little guidance as to how to run it. Each week, the team would receive a memo written out as if it were something that your supervisor (in industry) might send your way - the overall objective was clear, but there was little guidance as to how to proceed. Days before the lab started, we had to look at the equipment, imagine how it would work and also figure out which equations we would use to analyze the data. We would then have to make a proposal to the prof as to what our plan was and what data we would collect.

Now while we all (thought we) understood the equations being used, the biggest challenge we faced was making sure that we collected all the data that we needed when we did finally got into the lab and used the equipment. If we didn't get the data at that time, we were up the proverbial tributary without a proper means of forward locomotion. We would not be given a chance to back into the lab and rerun anything (much like industrial situations, by the way). So the best way to avoid the problem was to make up some data before we got into the lab, and run some calculations with it to make sure that we had all that we needed.

This actually provided us with positive two outcomes: first, we could verify that we were going to be collecting all the data that we needed, and second, by making what we thought were realistic guesses for the variables (as opposed to random numbers), we were training ourselves to anticipate appropriate values. If the actual values were significantly different, then we were able to learn why out hunches were so far off.

It's still an approach that I use (mentally) to this day - think first about the all the data that you will need and how you will get it. You may not get the results you want, but you will be sure that you can stand by what you do have.

Just make sure that you don't confuse your made up numbers with the real data.

Tuesday, November 01, 2011

Fringed Micelles and Photoconductivity

I generally do believe that a picture is worth a thousand words (or more), but sometimes, they can be misleading. Here's a perfect example of an image in a recent research paper (open access).
What you see is an iconic model of semicrystalline polymers – the famous "fringed micelles" - so upon seeing it, I immediately thought that I knew what the research was about: the crystallization and possibly the mechanical properties of semicrystalline polymers. I was wrong. But first some background: The image is made up of two principal components, the crystalline fringed micelles (the portions with multiple straight parallel lines) and the amorphous regions (the portions with the squiggly lines). Whole books have been written about how the volume proportions of each region can be influenced by molecular weight, thermal conditions, additives (particularly nucleating agents), externals stresses or strains, solvents, etc. Yet other books have been written about how the details of the structure (tie molecules in particular, stands that run out of one micelle and into another) influence mechanical strength, and I won't go into those details today. These subjects are quite broad and still actively researched, so it wasn't out of place for me to prejudge what the research was about.

But in fact the research was actually looking at the mechanisms of photo-conductivity in poly(3-hexylthiophene), (P3HT) which beside being conductive, is also a semicrystalline polymer.
(Notice the alternating pattern of single/double bonds? That conjugation is why the material conducts.)

The researcher found that the existence of the crystalline and amorphous regions in the solid is critical to conductivity. The absorbed photons created a charge separation, with the electron being trapped near the crystalline/amorphous interface and the hole being in the crystalline phase. Lower molecular weight materials, being mostly crystalline, do not have both of these regions and therefore lower electrical activity. The results were able to explain a wide range of conductivity results that had been previously reported without explanation.

So now the fringed micelle model is not only able to explain crystallization in polymers and mechanical properties, but also photoconductive behavior. Triple duty for a model – that's some heavy lifting. But this also suggests that the photoconductive properties of a given grade of P3HT can be adjusted by altering the crystallinity, albeit at the same time that the mechanical properties are being adjusted. I can see some contradictory optimizations in the future for some engineers. After all, what are the odds that the ideal crystallization scheme for the mechanical properties is identical to that for the photoconductivity?

Hat tip to Matteo Cavalleri (twitter @ physicsteo) for the lead.
Obadiah G. Reid, Jennifer A. Nekuda Malik, Gianluca Latini, Smita Dayal1, Nikos Kopidakis, Carlos Silva, Natalie Stingelin, & Garry Rumbles (2011). The influence of solid-state microstructure on the origin and yield of long-lived photogenerated charge in neat semiconducting polymers Journal of Polymer Science Part B: Polymer Physics : DOI: 10.1002/polb.22379

Monday, October 31, 2011

10 Halloween Scares for Polymer People

Let's hope that nobody sees these frightful creatures around their business today:
  1. ISO Auditors
  2. FDA Auditors!
  3. EPA Auditors!!
  4. Tax Auditors!!!
  5. Your resin supplier with their latest price monthly increase
  6. Environmentalists telling you that they are gathering a petition to put you out of business
  7. The manufacturing director telling you about the mishap over the weekend that bent the screw shafts and that replacement parts have a 4 week lead
  8. The research director telling you about the mishap in the lab over the weekend, which led to the sprinklers going off which led to...
  9. The sales director telling you that your largest client is going to 90 days net, and not because they want to, but because the bankruptcy court ordered it
  10. The government with a $500 million loan because they believe your company is something the country needs to invest in
Stephan King has nothing over this list.

Monday, October 24, 2011

John's Tricks for Free Access of the Literature

People in academic settings usually have enviable access to the scientific literature, but upon leaving the island, access to it can quickly diminish [*]. Large corporations will have good access, but for those of us in medium or small corporations, access is often limited. Subscriptions can be very high, and paying ~ $35 a pop for an article that may or may not be what you are looking for can also be an expensive proposition.

With that in mind, this post is an unorganized list of tricks that I have to try and find free copies of articles that you would otherwise have to pay for. This situation is dynamic and if I were to make the list again in another year, it would be different. Just keep in mind that there are no guarantees that any of these will work, but since you're not pay anything for this advice, that comes with the territory.
  • Many journal will provide open access within certain time windows. The most common approach is that access is free after 6 months. Examples of this include:
    • Science magazine, but only the research articles, not reviews, new stories, brevia, etc.
    • Proceedings of the National Academy of Sciences
  • In the other direction, the Institute of Physics makes all their articles available for free for the first 30 days after online publication. This usually means you if you see something in anyway related to your work, grab it right away as it will cost you later.

  • Many publishers will make the January issue of the current publishing year open access. This is true for the American Chemical Society and Elsevier.

  • Sign up with the journals of interest to receive their emails, such as their Tables of Contents. Every once in a while, they will alert you to free articles as well.

  • In a similar vein, other journals have blogs supporting them. A good example of this is the Royal Society of Chemistry, which has individual blogs for each of their journals. If a research article is discussed in their blogs, they will usually make it available for about a month or so.

  • A Google Scholar search for an article (I find using a good portion of the title works best) may show alternate mirror sites that have the article available. Look for hits that have a [pdf] annotation.

  • More and more professors are providing free copies to their published research via their own websites

  • Along these same lines, you can always contact the professors directly and see if they can supply you a copy of the article. This is the least desirable route as you may not get a quick response (or any response).

So that's what I do right now. It's not a perfect situation, but I have impressed many people here at work with my ability to scrounge up a free article at times. Sometimes however, you just have to breakdown and pay for the article. While I am all in favor of "open access", I have come to recognize that publishers do provide a valuable service that needs to be compensated, so if we ever do get to universal open access, the costs of it will be born some else than directly by the readers (as it currently is). If anyone wants to add to this list, feel free to post their tricks in the comments box (or you can email me personally at john dot spevacek at aspenresearch dot com). I will likely also set this up a permanent reference page too so that this doesn't disappear deep in the archives. [*] I recently was involved in an online discussion about this subject. The prof on the other side was arguing that students don't need to learn as many facts as they used to since they can access the information online. I hope nobody takes this advice - just wait until his students get into industry and try playing that game. If you are a student right now, consider yourself forewarned - his advice is unacceptable.

Friday, October 21, 2011

Those Chemicals Really Aren't That Expensive

I mentioned the other day the high price of a polymer that I was trying to order lab quantities of. We've all experienced this some degree, and my point was not to pick on any one supplier, or even question why their prices are so high. I blindly accept that there are good reasons for it, or someone else would set up shop, undercut their prices and win big (Why yes, I do believe in efficient market theory! Why do you ask?)

My supervisors on the other hand, assume that the prices that I am initially charged indicate that the chemicals that I am working with are too expensive to work with in the long run and that I should be working with something else that is cheaper. The best argument I have found to set them right is this: look at the same catalog for a commodity chemical such as isopropyl alcohol (IPA) or polyethylene, and see how much that is marked up. Depending on the exact catalog and purity, a liter of IPA goes for $30 or more, even though I can go drive 2 minutes down the street to the K-Mart and buy the equivalent for a couple of bucks. So if the chemical I am ordering is going for $60 bucks a liter, that says to me that in bulk it will be about $4 a liter. When I put these numbers in front of my supervisor, suddenly all the talk of expensive chemicals goes away and I can proceed in peace.

Thursday, October 20, 2011

The Inventors of Kraton...

are Geoffrey Holden and Ralph Milkovich. The answer was supplied by Frank Van Haste on Twitter. A quick Google search confirms this, but raises more questions. If seems like the original patent (US 3, 265,765) was filed on January 29, 1962, and yet the Belpre plant was built in 1961. [*] So was the plant originally built for other products that weren't as successful as Kraton? Or maybe there is another scenario: At that time, the US had a 1-year grace period between when a product was made public and when you filed for the patent. Did Shell wait until the last possible minute to file? (I find this implausible). Fortunately, these questions certainly don't bother me near as much as who the inventors were.

[*] That explains why I couldn't find the inventors myself, as I only looked at patents that were filed in the 50's.

Who Invented Kraton?

I saw in a trade journal that Kraton is celebrating it's 50th anniversary. Actually, it was the 50th anniversary of the Belpre Ohio plant where the stryeneic block copolymer is made. There are many variations of Kraton, but they all fall under the general umbrella of being tri-block copolymers with styreneic endblocks and a rubbery midblock. (If I remember correctly, half the styrene blocks are made first (anionic polymerization), then half the midblock is attached, and then midblcok portion is capped by a coupling agent. The coupling agent then brings to two halves of the polymer together to create the triblock product.) When heated to 100 oC or more, the endblocks soften and flow, but upon cooling they phase separate to form styreneic blobs in a rubbery matrix. Since the rubber is physically crosslinked, not chemically, the material can be processed with standard equipment and will reflow repeated, unlike vulcanized rubbers or other crosslinked rubbers. The rubber is used as the base for an immense number of materials - box sealing tapes, diaper tapes, footwear, as an additive to asphalt...

So the question occurred to me: who invented Kraton? There are lots of polymers where I can name the inventors: Carouthers invented nylon, Ziegler-Natta "invented" HDPE (or at least the catalyst that made it possible), Stephanie Kwolek invented Kevlar, Roy Plunkett invented Teflon,... So how come Shell has kept the inventors names under warps? I tried looking for relevant patents from the 1950's and 60's but didn't find anything that said to me: "Kraton!"

Any old Shell Chemical guys that can answer this? Considering that billions have been made from this material, someone should have had a pretty big reputation around the company.

Wednesday, October 19, 2011

It costs HOW MUCH?!?

We've been looking lately at polymers that have acidic products after hydrolysis. Polyesters are the natural choice, with aliphatic polyesters (such as polylactic acid (PLA)) being the preferred choice (as opposed to semi-aromatic polyesters like polyethylene terephthalate (PET), polyethylene naphthalate (PEN)…).

Polylactic acid (PLA) is often called polylactide, which is perhaps a more technically correct name. In the polymerization of lactic acid, water is produced as a byproduct and it is difficult to reach high molecular weights with the water hanging around the reactor. Instead, the lactic acid is first dimerized to form a lactide – six member ring (and water).
The water is now easily separated from the lactide, and the lactide can then undergo a ring opening polymerization to form polylactic acid or again, the more technically correct name of polylactide [1], without creating any water.

If you study the illustrations above, you can see that this two-step polymerization can be performed with all α-hydroxy acids. Glycolic acid is a shorter α-hydroxy acid that forms glycolides that then are polymerized to polyglycolic acid (PGA). I thought PGA would be another good candidate for our screening tests but was floored by the price. One source has 10 g for $450! [2] [3].

Now I am well aware that PGA, and various PLA-PGA copolymers are commonly used for medical fasteners (sutures, staples…) and that those materials will be horribly expensive, but this particular application is worlds away from any medical usage. I'm just looking for some cheap industrial grade and am not finding it.

[1] If we are going to insist that all (additive) polymers are going to be named on their starting materials, than we better get rid of polyvinyl alcohol – it will now be called hydrolyzed polyvinyl acetate – polyvinyl butyrate – it will now be called butyrated polyvinyl acetate – and

[2] You know you looking at an expensive material when the material prices start with 1 gram quantities.

[3] The same source has HDPE for $37 a kilo, about a 16x markup over bulk commodity pricing. That "initial" markup is not what I am complaining about. I expect to be paying that for small lab quantities.

Tuesday, October 18, 2011

Slightly Toasty Polymers

Thermal degradation of polymers, if carried out far enough. is pretty straight forward – all the carbon is oxidized to CO2, the hydrogens are oxidized to H2O. As for the heteroatoms, oxygen is already mentioned, and nitrogen will go to NOx.

The more interesting results occur when the material is only partially degraded. I ran across a research highlight discussing the burnout of ethylene vinyl acetate (EVA) copolymer in powder metal molding. In powder metal molding, the metal powder is mixed with a polymer emulsion, molded and baked so that the polymer burns and the metal particle melt and flow together. Keeping the shape is critical during the baking step and the research found that certain polymers are better than others in this regards. The research looked at what specifically was occurring to the polymer during the burnout and found that the acetyl groups hanging off the polymer backbone broke off and (probably by abstracting an adjacent hydrogen atom) became acetic acid. [1] The result is a double bond forming along the backbone – what the authors call an ethylene acetylene copolymer. [2]

I was not aware of this chemistry prior to reading the writeup, but it actually isn't that new. Research has already been published on using the partial thermal degradation of as a means of preparing polyacetylene.

Given that the unsaturated polymer would be inherently stiffer than a saturated polymer (the geometric options around a double bond are far less than a single bond), it is not surprising that the partially finished metal objects are benefitting from this degradation product.
Lastly, lest you think that all substituted vinyl polymers degrade in this fashion, polyacrylonitrile follows a totally different route, one that is used to create carbon fiber (albeit, this is done in an inert atmosphere).

[1] Isn't this strange? Most polymer chemists are familiar with acetic acid forming during a polymerization step (of silicones most commonly), and not as a degradation product.
[2] A similar polymer forms when PVC partially degrades – HCl comes off leaving double bonds along the backbone. If there are enough double bonds that form alternating with single bonds, the resulting conjugation absorbs visible and UV light (depending on the conjugation length). Under the right conditions, the longer visible wavelengths are removed leaving only the shorter, redder ones. If the PVC is already white (such as is used in windows), you can end up with pink windows! (And unhappy customers!)

Monday, October 17, 2011

How to (NOT!) Determine PVC Rheology

We all know that the internet is filled with lots of bad information. A good example is this page entitled "How to Determine PVC Rheology". The strangest part of this is that this was published on "", a site that is normally gives advice for general consumers (gardening tips, financial advice,...). Why anyone on the site would be interested in PVC rheology is beyond me.

Overlooking all this, the advice given is still awful. You can tell that there is a trainwreck coming anytime an article starts out with false compositional breakdowns of a material such as this:
"Polyvinyl chloride (PVC) is a synthetic thermoplastic resin made of 57 percent chlorine from industrial salt and 43 percent carbon in the form of ethylene from oil and gas sources.
First off, PVC is made from vinyl chloride monomer (VCM), which is what in fact is made from chlorine and ethylene. You don't just dump NaCl and oil/gas (or even ethylene) in a reactor, start it up and voila! - out comes PVC.

Unfortunately, the article has not yet bottomed out.
"Once formed, PVC can be resoftened by heating, with melting occurring at approximately 180 degrees Fahrenheit.
180 oF??? Only if it is greatly plasticized. The melting temperature of PVC is all over the map, probably more than any other plastic, and depends greatly on the formulation. 200 oC is not out of the question in some cases. But wait, there's still more:
" To properly manufacture PVC products, manufacturers study its flow properties when melted to learn how to successfully pour it into injection-molding machines."
Pouring molten PVC into an injection molding machine? Certainly the rheology of the pellets that are normally used to feed an injection molding machine could be what the author is referring to, but once you read the next sentence, you find out that that is not what was meant.
" Rheology is the study of how matter flows. So when you determine the rheology of PVC, you determine how it flows when melted."
This is only half true as the rheology of non-molten materials are also studied too.

At long last, the article then finally gets to the information on how to use make a measurement using a torque rheometer. The details are so insufficient that no one can possibly run it correctly even if they have access to the instrument. The final kicker is written in the "Tips and Warning" section:
"There are three typoes [sic] of rheometers: capillary, parallel plate and torque rheometers. Torque rheometers are the rheometer of choice when determining the flow proerties [sic] of polymers."
All of this is wrong - the types of rheometers are endless, and a torque rheometer would be the rheometer of choice in only a few situations, (such as when a test specifically calls it out, or if the operators are not trained or skilled in other techniques or...).

If this isn't enough of a laugh to start your morning, then check out the article that is listed in the "Related Articles and Videos" heading: "How to Use a UV Light to Evaluate PVC Rigidity" I kid you not! Throw away your tensile testing machine - all you need is a UV light!