Thursday, February 25, 2010

Cel Conservation

This may come as a shock to the younger readers of this blog, but there once was a time in ancient history when animation was created without the use of digital technology. Using analog technology, humans created animation by rendering drawings one frame at a time, with many of the drawings first being created on clear plastic films of cellulose nitrate. Theses were called "cels" for short. Cellulose acetate was eventually used as a replacement for the nitrates.

As an even larger shock, most of the movies created with this technique were well received and are fondly remembered by the public. The cels, no longer serving a useful purpose, are being recognized for their artistic value by collectors and curators. But there is a problem: cellulose nitrate, besides being flammable [1], the material doesn't age well. Many of the cels are starting to seriously degrade. The Getty Conservation Institute and Disney are now working together to better understand the degradation and finds steps to further reduce it.

We have and continue to do lots of work here at Aspen Research regarding polymer degradation, so I can firmly stand by the last two words of the previous sentence - they will be able to slow degradation down, but it can never be stopped, especially after it has started. Nitrogen blanketing is a likely option, as are other inert gases (argon is quite common); low light conditions and even avoiding certain wavelengths [2] altogether are also important. I would imagine that all the film stock is not of the same quality and some impurities are going to cause more problems than others. It's a fascinating project, and I wish I was involved.

[1] The flammability of cellulose nitrate served as an important plot aid in the films (Nuovo)Cinema Paradiso (one of my all time favorites - the kissing montage at the end of the movie is so poignant) and Quentin Tarantino's "Inglourious Basterds" [sic].

[2] It is often assumed that shorter wavelengths, being of higher energy are more destructive than longer wavelengths. This is not always the case (we've made lots of money from people who believed otherwise). See for instance: A. L. Andrady, Advances in Polymer Science, 128, 1997, 47-94

Wednesday, February 24, 2010

And the problem is...?

I'm certainly missing the issue here. IUPAC is concerned about misleading terminology (doesn't make just a horrifying lead in?) in this case (open access) the term "polydispersity index". Huh? I never knew there was a problem.

Certainly there is some logic to the case:

"Monodisperse’’ is a self-contradictory term and ‘‘polydisperse’’ is tautologous."

...but is the existing term really that confusing? Is that tautology driving someone insane? Worse yet, the new definitions that are proposed all use the Unicode 0110 character, "Capital D with Stroke":

The general symbol Đ is introduced for dispersity to avoid confusion with the conventional use of D for diffusion coefficient.

That's going to go over well isn't it? Or do you just think that people will keep using "polydispersity index"?

How well have they done with previous interventions? Look at what they came up with for "inherent viscosity" and "intrinsic viscosity": "logarithmic viscosity number" and "limiting viscosity number". Yes something needed to be done as both "inherent" and "intrinsic" can be confused especially when abbreviated as "I.V.", but the new terms are being ignored. A Google Scholar search for use of "intrinsic viscosity" from 2000 to 2010 yielded about 16,000 hits while a similar search for "limiting viscosity number" yielded only 450. As suspected, that term is DOA and the same will be true for "dispersity".

Tuesday, February 23, 2010

Spec Sheets

Of all the tasks that I have to undertake, looking through spec sheets is just about at the bottom. It has to be for everyone too, right? How's this for a starter list:
  1. What properties are listed varies from sheet to sheet.
  2. What test procedures were followed varies. Sometimes it's an ISO standard, sometimes it's an ASTM, sometimes it's an internal procedure. Plus there are plenty of user industries that have their own tests such as the SAE, PSTC...Consider impact testing. There are the notched, unnotched, and reverse notched Izod tests, (the ISO test output is energy/area, while the ASTM is energy/length), the various Charpy tests, the Multi-Axial Instrumented Impact Energy test, a whole gamut of temperature conditions...
  3. The whole metric-English unit dichotomy.
  4. The inadequacies of the test designs in general. Melt-flow is a disaster, heat deflection temperature under load is representative of nothing...
Rectifying the situation is not possible. Despite the ever increasing consolidation within the industry, any hope for standardization is futile. The best one can hope for is that standard test procedures are used, ISO, ASTM or whatever.

Monday, February 22, 2010


I certainly could be "Czecho-centric", but it seems like there is an unusually large number of people studying polymers who are of Czech origin or a descendent. With a last name of Spevacek, I certainly fit the bill, but I am not alone. Back in grad school I discovered while browsing the literature (back then, browsing the literature was a physical activity involving many musty volumes of bound journals) that there was in fact a "J. Spevacek" who has authored numerous articles on polymer science, mostly involving NMR analysis. This individual is Jiri, not John, and is not known to be a relative of mine. (Spevacek is actually not that uncommon of a name - there are at least three other "John"s that I know about in the US. The name is the word for a singer or cantor - obviously a trait that is not inherited!)

Jiri works for the Czech Academy of Sciences and a search through Google Scholar finds over 140 hits. One year while at a former employment situation, I found all the publications that "J. Spevacek" had published that year and attempted to convince my supervisor that I should have gotten a promotion because of all my hard work. That didn't get too far.

Friday, February 19, 2010


It happened yesterday when I wasn't looking, but since I uploaded the Sitemeter back in October, this blog has crossed over the 1000 visitors threshold. Some sci-tech blogs probably get that in a day, so it's only meaningful to me. The total vistors over the life of the blog will remain unknown, as it was started almost three years earlier.

Looking back at the Climate Debates

I found a refreshing take on the Global Warmings wars in this blog entry at the NY Times. It's written from the imagined perspective of a historian 200 years from looking back at the climate change debate. It's short and doesn't really come down on one side of the issue or the other, but instead focusses on what impact science is having on larger society and vice versa. It really is sharp and biting, and gels together a number of points that I've been feeling in the last few years.

What really disgusts me are the comments. The same-old same-old. "It happening." "It's not." "You're stupid." "Am Not" "Am too!" "Am not!"...

Thursday, February 18, 2010

A Concept Kitchen

We've all seen "Concept Cars" - the ones at the Auto shows that pull together a huge number of futuristic ideas. They capture the imagination, but are not in production and no one has any immediate plans to put them into production.

Given that they exist at all, the term "Concept" is really inappropriate. They are not the fruitful figment of someone's imagination - they actually exist. Compare that with this concept kitchen appliance that obviously would require intensive use of polymeric materials.

Since we're dreaming, I'm thinking that if you put your fist deep into the surface you could then have a deep-fryer, and if you rake your fingers along the surface, you could create a grill. But how would you make a panini or waffle with it?

Wednesday, February 17, 2010


So we'll see how well tweeting works out.


The only part of chemistry that I really never cared for (and still don't) is electrochemistry. This video is certainly of interest however. Now I'm curious about how well oranges work compared to lemons, grapefruit...

Measuring the speed of light using a standard microwave oven and chocolate candy.

Given Climategate and other recent recanting, news of Texas suing the EPA over regulation of green-house gases doesn't strike me as being such a Quixotic quest anymore. Note: Back in 2007, the US Supreme Court ruled that the Environmental Protection Agency could consider regulating CO2 and other green house gases. This did not take away from Congress the power to also act on the matter. At that time, Bush was president and decided not to do anything. Ditto for Congress. Under Obama, Congress has attempted to pass laws ("Cap-and-Trade"), but the EPA is also now threatening to act as Congress is moving slowly on the matter. Either way, the suit(s) will eventually end up at the Supreme Court. Given their ability to handle math and other scientific matters so well, it's anyone's guess as to the outcome.

Monday, February 15, 2010

Bicyling and Plastics

Looking at the links on the left side of this page, you can tell that I am a bicycle racing fan (used to race, and would love to do so again). Normally there is not a lot of overlap between the racing and plastics/rheology, but sometimes a link can be made.

Unless you are a cyclist, this report of a fire in a plastic sheet factory in the town of Roubaix (pronounced ROO-BAY) will mean nothing to you. Roubaix is a small French town (pop. 100,000) on the Belgian border, but it, or more properly, the Velodrom within it, is the finish line of the the most famous 1-day race of all, Paris-Roubaix. Nicknamed the "Hell of the North", the race is loved and hated for the cobblestone roads that it passes over. But these are not the cobblestone roads that we have here in the US that are made from bricks, these are made from stones: Imagine racing over that...I certainly have no sympathy for a pothole in a racetrack.

Wednesday, February 10, 2010

Valentine's Day is Coming...

...but there is still time to find your favorite rheologist some fun tees. Even the dog can get in on the good times.

Tuesday, February 09, 2010

I gotta look closer

I've got more than enough dried/blackened/molten and decomposed solutions/polymers/composites lying around the lab. I just need a good magnifying lens and some time and then I can find my own Michael Jackson image. Or Elvis. Or the Pope.

Sell it on ebay - there are more than enough avid fans will to spend some green on this stuff - and then I can be RICH! RICH! RICH!

Monday, February 08, 2010

Plasticizers that Stay Put

This new article in Macromolecules (open access!) seems like it will be the hot topic of the week, with some already claiming that it is a "safer" plastic.

Short and sweet, the researchers added a thiol group to the benzene ring in DOP,which then later reacts in a solvent (cyclohexanone) with the PVC via an unidentified reaction. There is loss of plasticization-strength-per-unit-mass, but the plasticizer does seem to stay put looking at what a hexane extraction process can pull out. The authors are so bold as to say that the extact is "zero"[1]. This certainly is an aggressive test to look for plasticizer movement, but it would also be useful to look at the surface over time (heat can certainly be used to accelerate the diffusion.)

I can't that I'm excited about the use of solvent in the DOP + PVC reaction step. Solvents are certainly something that industry is avoiding more and more each week. And the synthesis uses more than just the cyclohexanone I noted above. An H2O/methanol wash is used to stop the reaction, and then THF/hexane is used to precipitate the PVC. That's three different solvents used to modify a commodity plastic. Certainly some industries can consider affording this (I'm thinking medical tubing), but it would certainly require many additional steps of testing to ensure that there are acceptable levels of residual solvent in the final PVC.

Despite the hype, I don't think you'll find this commmercialized anytime soon.

One last thought (added on 2/9/2010): The hexane extraction doesn't even have a control to show how well hexane could extract unreacted plasticizer. Until that is done, there should be serious doubts about the validity of this study.

[1]Note that this is incorrect - it should be state that the extracted plasticizer was below the detection limit. Zero means zero - that there was not a single molecule present. Worse, the detection limit of the technique was never determined, so it it not clear at all how small amount they can detect. The first data point in Figure #5 for the non-modified DOP is at 1.5 mg/ml (1.5 ppm), which is nice but certainly not zero. I'm dissapointed that the reviewers let this go by.

Friday, February 05, 2010

A new concept in hearing aids

This story on a bone conduction hearing aid you wear in your mouth caught my attention far more than you might expect. My previous employer was a manufacturer of an implantable hearing aid. It was a pretty cool device that worked on people with middle ear hearing loss. A sensor was attached to the incus to sense the incoming vibrations and convert it to an electrical signal. The signal was amplified (the electronics were in a small case that is under the skin and just behind the ear) and sent to a transducer on the stapes which then used the natural operation of the inner ear to do the rest of the work. (My particular job was to protect pretty much everything with various polymeric materials so that nothing would corrode.)

A huge advantage of the technology over regular hearing aids was that it didn't fill the ear canal, a body part that is evolved to collect and isolate sounds, particularly conversations, in a noisy setting. Another advantage was that being completely implanted, you could even swim with it.

One of the challenges that we faced arose because hearing actually involves the whole head. All the bones in your head can be used as vibration collectors to produce signals in the inner ear, thus leading to bone conduction hearing aids. While bone conduction seems like nothing but a positive, in our case, it was a huge negative as it was a troubling source of feedback. If we overdrove the stapes, the signal could be tranmitted through the head back to the incus, which would then further amplify the signal, ultimately leading to feedback that even Jimmy Hendrix could have never imagined.

Furthering the problem was that we could not come up with a set of synthetic materials that would mimic the bone conduction pathways in the human head. That led us to our the only option available:

we worked with whole human heads.

(Now that's something I never thought I would encounter in my life as a polymer scientist!)

"BPA Free"?

I ran across this photo while looking for images of clarified polypropylene. The caption states that the baby bottles are made from "BPA-free" clarified polypropylene.

Of course it is. Polypropylene is made from propylene, not BPA. Considering that the government won't let companies advertise something as "cholestrol free" if the product never had any cholesterol in the first place (vegie oils for instance), it certainly would be appropriate to have similar restrictions regarding BPA.

Wednesday, February 03, 2010

We're just leaches

I've always loved giving the guys from Dow Corning [1] a hard time about their prices because of an apparent contradiction. Silicon is the second most common element in the earth's crust - look at any beach and you can can grab piles of it in its oxided forms. Compare that with carbon -15th on the list, almost 600 times rarer even more so if you consider that the largest source of carbon for industrial chemical reactions is from petroleum, not coal or natural gas.

So why are silicones so dang expensive? Especially compared to oil-based products that require huge investments in exploration, drilling and refining. This has question has nagged me for nearly 20 years, the Dow Corning reps have never had a good answer [1, again], nor has anyone else.

I think I stumbled on the answer last week through a long twisted train of thought [2]. Compared to the amount of petroleum that is turned into gasoline, the amount that is turned into chemicals is quite small. Much of it is impurities that would ruin gasoline. For example, anything with a double bond is trouble (which is why gas has a short shelf life) but that trouble is a great starting point for making polymers or anything else of interest.

So organic chemistry is basically just a leach on the world's petroleum business, and as a result, we (organic chemists) have cheap access to a supply that would otherwise be terribly expensive. Without internal combustion engines, the Aldrich catalog would be pretty small. The silicone industry on the other hand, despite having a cheap feedstock, has to process it all without the benefit of a huge non-chemical demand such as automobile fuel. If cars could run on a silicone fuel, things would be different.

[1] This is not to pick on Dow Corning or portray them in a bad light. It's industry wide. Other silicone polymer manufacturers could easily be inserted in here instead. It's just that I've had more contact with DC than the others.

[2] I was listening to Fresh Air Radio [3]and heard an ad for a local coffee supply company (sorry, can't plug the name as I don't remember it - I never learned to drink coffee so the company's name is pretty useless information to me) that delivers fair-trade coffee via bicycles. I'm sure the company thinks that they are saving the planet by not using a car or truck for delivery, but it also occurred to me that the only reason that they can use bicycles is because cars exists. Without all the cars in existence, we would not have all the roads that the bicycles ride on, the rubber for the tires or inner tubes or brake pads or lubricants or... (We actually would have them, but they would be terribly expensive.) But the end result is still the same - the bicycle delivery system is basically an option only because another larger option (cars) exists.

[3] I listen to the station for 2 reasons - 1) they play a great mix of blues and jazz in the afternoons while I am driving home and 2) they run "Democracy Now!" with Amy Goodman[4].

[4] CAUTION!! Only attempt this next procedure if you have a very strong tolerance for holding simultaneous contractions contradictions in your head at the same time. And I am talking about something far more puzzling than the particle-wave duality of light. CAUTION!! You have been warned.

This works best on a day where there is a major news story that everyone is talking about. Recent examples would be the Haiti earthquake or the State of the Union address. Put on Amy Goodman for a few minutes. Then switch it to Rush Limbaugh. Then go back to Amy. Then back to Rush. Repeat until you cannot take it anymore and then wonder how these two people can be contemporaries on the same planet.