Grammar

As one prone to this faux pas, I had to laugh:



From Saturday Morning Breakfast Cartoon, just so you know where I got this from.

Scanning Plastic Films for Defects

A new PR blurb from the IKV - Aachen about detecting individual sublayer thicknesses in multilayer films is short on details about the technology used. It's somewhat disappointing, but it really doesn't matter to me as it pretty clear that they have not solved the most fundamental problem in looking for defects on film lines.

Plastic films and the equipment to make them have been around for some time with few significant changes. Whether processed as blown or tentered film, at some point after the orientation is complete, some equipment is used to measure the film thickness. The simplest gauges just measure the overall thickness, while more sophisticated equipment such as is disclosed here, can measure one or more individual layers in a multilayer film. Regardless of the equipment used, they all suffer from a common problem: the equipment only examines a small spot on the film. In an attempt to cover the entire width of the film to look for side-to-side variations, the equipment moves back and forth across the width of the film to look . While this initially seems to be satisfactory, the equipment is only still only examining small section of the film. Let me show this with a picture:In this picture, the newly made film is moving in down the page, and the scanner is moving from first left to right and then back again. Equivalently, the film can thought of as being stationary and the scanner is then moving along the dashed arrows. The dashed areas show the areas of the film that are examined, and conversely, the areas that aren’t. The exact path examined depends on the speeds of both the film and the scanner. The relative velocities of the film and the scanner determine the amount of film examined. The higher the scanner speed, the more the coverage, but you can still see that there will be gaps in the coverage.

The situation would be much improved if the scanner would examine the full width of the film at the same time. Then the area examined would simply be determined by the measurement time and the film speed.

These problems are widely known in the film industry, so if someone had AFFORDABLE equipment to scan the entire width of a film at once, they would be certain to mention it in their press release. Keep in mind that some film operations can produce films that are 8 meters wide, so this is not a small challenge.

Nanoemulsions for Dissolving Polymer Films

When you see this as the opening of an abstract, you know you're in for a fun read:

"Conservation of works of art often involves the inappropriate application of synthetic polymers."

The article certainly doesn't disappoint (open access). In this case, the researchers were trying to selectively remove polymeric films that earlier conservationists had applied to wall paintings in an effort to isolate the paintings from the environment. To the conservationists' credit, the paintings were isolated from the outer environment. Unfortunately, this led to crystallization of salts in the pores of the wall, thereby putting pressure on the coatings which then peel off the wall, often taking the paint with. The coatings also degraded in such a manner that their removal with solvents is either impossible or undesirable as the solvents would pass into the pores taking the coating with them. The only option was to use emulsions of the solvents in water.

The authors spend quite some time preparing and characterizing their nanoemulsions - I won't go into the details here. What I really was excited about was the effort they put into studying the mechanism for the polymer removal which involved light scattering experiments to characterize the emulsion particle size, and AFM to look at the removal of the coating over time. The results are worth is as they are able to propose the following mechanism:

The emulsion particle, consisting of sodium dodecyl sulfate (SDS) and 1-pentanol (1-PeOH) as (co)emulsifiers for ethyl acetate (EA) and propylene carbonate (PC), moves to the surface and releases the solvents into the polymer. At an optimal polymer/solvent ratio, the polymer is able to disperse itself into the water largely without the aid of the surfactants. The surfactants then reform into micelles, albeit smaller ones as they are now lacking in their solvent core.

I love seeing new mechanisms such as this, particularly when they are well documented. If you've studied emulsion polymerization chemistry, then you know that micelles are dynamic entities, not the static objects that they are diagrammed as.

Blogging Discussion at the ACS Meeting

This week's ACS meeting (wish I were there, but it was not to be. Boston is a wonderful town for a conference) had a panel discussion on blogging. The emphasis was on pharma rather than general chemistry, but one comment from across the panel of bloggers I found interesting: They all seem to notice a drop in readership when IP is discussed.

Being guilty of discussing IP and other legal issues on here from time to time, I will have to look back at the viewer reports more closely to see if that trend exists here too. Or are all my readers more broad-minded than pharma chemists?

The Deborah and Weissenberg Numbers

Engineers have always loved dimensionless numbers [*], groups of variables where the units cancel leaving them free from the chosen system of measurement. (i.e., the Reynold number for a system has the same value when measured in SI or English units.) Rheology is generally lacking in dimensionless numbers except for two - the Deborah Number and the Weissenberg number.

I must confess that I never really understood there to be much difference between the two, but a new article in the Rheology Bulletin (pdf file, open access, article starts on p. 14) makes clear the difference. The author is John Dealy of McGill University. John is someone who's ability to write clearly on rheology I have always greatly admired and envied. The article, not one of his best, has a number of fine details that I will not discuss here, such as how to work with a single relaxation time when it is known that the system has a distribution of such times. I would highly recommend reading more than just my summary.

As for the numbers, the Deborah number is ratio of the relaxation time of the polymer divided by the observation time. Fine points that I've never caught in the past are that the observation time is not the reciprocal of the deformation rate, and that the Deborah number is identically zero for steady state flows. The deformation rate however, does appear directly in the Weissenberg number, which is defined as the product of the relaxation time and the deformation rate.

It's apparent that I've been using the Deborah number too often when I should have been using the Weissenber number. I'm going to have to work this over in my head a few times as the distinctions clearly exist and I want to get it correct. Fortunately, I've not had to use the numbers too often, and the mistakes I have made have been made by others as well, but I certainly intend to do better in the future.


[*] One of my ChemE professors told us that he loved to taunt chemists by talking to them about his favorite dimensionless number - the 2nd Damköhler number. He was able to double tweak them with this because it also implied that there was a 1st Damköhler number that they also didn't know about.

Preventing Spam on this Blog

There has a been a significant increase in spam comments on this blog [1]. So far I've only needed to moderate comments on posts that are more than 30 days old. I've resisted all urges to use the CAPTCHA system as I find it often difficult to use [2]. If the spam increases and I have to moderate all comments, I am pretty convinced now NOT to use the CAPTCHA system - not because computers are cracking the code, but because you can now efficiently pay people to do it for you.

That's right, through the miracles of modern technology - the internet and cheap third world labor, spammers can now pay as little as 75 cents for someone to crack 1000 codes. Such a deal. So be warned all you spammers out there. You won't get to me. You're listening, right?

(It's a Friday afternoon at the end of a long week glued to the rheometer and I'm a little punchy. Have a good one :)

[1] Going from nothing to 2 or 3 a week is a significant increase, isn't it?

[2] Not the worry, I'm getting a prescription for bifocals in a few weeks!

Plastic in the Oceans

Plastic (or any other type of man-made waste for that matter) has no business being in the ocean. Period. But with all the shrill statements on how the amount of plastic is increasing, a new report published in the esteemed journal "Science" (subscription required) today has found that the amount of plastic in the oceans is not increasing despite increase production of all plastics on land.

"The team has now analysed data from the past 22 years - more than 6,000 net tows- to try and quantify the amount of plastic in the western Atlantic and the Caribbean...Perhaps the most surprising result... is that they didn't see an increase in debris over time. " [*]

The authors also correctly point out that this work is only for the North Atlantic Gyre and cannot be extrapolated to other areas.

This is obviously good news as it appears that efforts over the past decades to reduce ocean pollution have been somewhat effective. If they had been totally effective, I would have expected to amount of plastic to decrease due to degradation. It appears now that the rate of input is equal to the rate of degradation. If the rate of input is less than that of the degradation, then the amount in the gyre would be decreasing. This is certainly the desired goal.

[*] From the RSC summary of the article. (Open access)

Updating Your Resume

In most companies, if your manager told you to update your resume, that would not be a good sign. Either the company is going under, you're losing your job, the company is being sold...

The situation is quite the opposite here in a contract R & D company [*]. When trying to sign up new clients, the clients will often ask to see the resumes of the people that will be doing the work. As a result, our managers tell us quite often to update our resumes, not because we will be working elsewhere soon but because we could be receiving more work soon.


[*] A term used quite a bit in the pharma industry for a company such as our is a "contract research organization", quite commonly abbreviated as CRO. I've been trying for years to figure our if CRO is a term with a legal definition for the FDA or not (would we have to be registered, undergo audits...). It would be nice to advertise ourselves as a CRO if that is not the case.

The Wall Street Journal and "Glass Transition"

Those are two terms that I never thought I would see together, but it has happened. Today's Wall Street Journal has an article about the compostable Sun-Chips bag that has been discussed before on this site.

The primary focus is on the noisiness, which they quantify at 95 decibels. But this is what had me in a jaw-dropping pose:

"So why is the packaging so loud? The new polymers have a higher "glass transition temperature," which is when a polymer goes from a harder, glasslike state to a rubber state. Because the transition to rubberiness happens a bit above room temperature, the bag is kind of crispy and crunchy..."

Imagine that! The Wall Street Journal actually using the term "glass transition temperature" and then defining it! I can't say this has never happened before (a search of their website produced zilch, but I don't think the search covers the entirety of the Journal's history, ditto for Google), but it was sure a shocker.

What's next, rheology? Non-newtonian viscosity? Viscoelasticity?

The Dark Days of Summer

If you are fortunate enough to live in the north woods, then you know that the "Dog Days of Summer" (Wiki) are followed by the Dark Days of Summer. These are the days that our house gets to be quite dark inside even at midday with the sun shining.

The sun is now taking a lower path across the sky so that the sunlight cuts across a wide swath of tree leaves, effectively blocking and scattering much of the light. This will continue and worsen in the weeks to come until the leaves fall.

This darkness does not occur in the Spring as the leaves do not come out until early May and are rather small for a while at that. By that point, we are only a month or so before the solstice and the sun is on a quite high trajectory.

Branding Polymers

The Highline Polycarbonate blog has an interesting post on branding and polymers. They have some interesting data which raises a number of questions. I posted my thoughts already over there; I would encourage you to at least read the post and then feel free to post your thoughts as well.

Eliminating Supplemental Information

The Scholarly Kitchen is reporting on the Journal of Neuroscience discontinuing "Supplemental Information" (often called "Supporting Information"), abbreviated SI. This is information that is freely available on line to help support a published article. In chemistry, this can often include NMR or FTIR data to show that the molecule that was stated to be synthesized was in fact synthesized, or it can be additional plots run with different samples to show that the representative plot in the article was in fact representative. (This happens a lot in rheology as rheologist often have a great excess of data.)

I've always found the information (or at least knowing that it exists) to be helpful. By having SI, articles can be kept shorter and have good flow - the details are elsewhere, much like a footnote. Articles often have page restrictions, but SI, being electronic, is without such restrictions.

The editors of the noted journal sees all of this as problematic for both the authors and reviewers.

For the authors,

"With few restrictions on space, reviewers may place additional demands on authors, requiring them to perform and add new analyses and experiments to the supplemental data. Often these additions are “invariably subordinate or tangential,” Maunsell maintains, but represent significant work from the author and thus delay the publication process. Supplemental data thus changes the expectations of both author and reviewer, leading to what he describes as an “arms race:”

And for the reviewers,

"Reviewer demands in turn have encouraged authors to respond in a supplemental material arms race. Many authors feel that reviewers have become so demanding they cannot afford to pass up the opportunity to insert any supplemental material that might help immunize them against reviewers’ concerns."

But there is also the truly laughable perspective of the journal:

"Validating supplementary data adds to the already overburdened job of the reviewer, Maunsell writes. Consequently, these materials do not receive the same degree of rigorous review, if any at all. At the same time, the journal certifies that they have been peer-reviewed."(emphasis added)

I say laughable as while I greatly value peer-review and am an active participant and strongly believe it should continue, I never look to a journal to certify anything. A peer-reviewed article has simply been sent out to reviewer and they have sent reviews back. I don't know what the reviews were, if they were done by competent people, if they loved the article, hated it or whatever, and I also don't know if the reviews influenced the editor in the least. I certainly know that everyone reviews articles in their own manner and that that manner may not even be consistent from paper to paper. (I'm not.)

Add to this the knowledge that any paper can later be retracted and you have reduced the supposed certification to vapor. Peer review: three people looked at it and liked it. That's all, nothing more. It is not a proof of correctness, it's just proof that three people looked at it and (probably) liked it.

Tip of the hat to Matteo Cavalleri for the lead.

Color Coding

The journal "Nature Methods" has a 1-pager in the August 2010 issue (see [1] below for access comments) on the use of color to present data and some of the challenges. Most of us are familiar with FEA output that shows stress/strain/temperature or whatever in a 3-D illustration, with various colors equated to various values of the variables. While the author of the article has his own criticism of some practices in using color, I think most of those are weak [2] and he misses the real issues.

To me, the critical issue that needs to be addressed in every case is whether or not the color scale corresponds to the numeric scale of interest. Too many software packages just autoscale the output to the ROYGBIV scale and call it a day. Maybe you are lucky and it works, but in most cases, I've found it necessary to have the color scale adjusted (often multiple times) so as to focus on a subrange of the variables (perhaps to clarify the coloring), or to use a logarithmic scale or some other issue. (I can recall one case where a dry run for an isothermal slab showed a non-isothermal asymmetry. Wethink this occurred because the FEA was started in one corner and was accumulating errors as it moved across the slab, all of which were very small even in aggregate, but when the autoscale coloring was completed, there they were. Upon rescaling, they of course disappeared.)

One valid point made by the author is addressing some of the optical illusions that can occur. We all seen examples were a color can look to be different if the neighboring colors are different. The approach suggested is to not only scale the colors, but also the saturation of the colors - basically use the gray scale as a second dimension. An added advantage is if the output is later printed in B & W instead of color, all the information is not lost. It's a good idea, one that I will see if I can get our FEA guy [3] to buy into.


[1] Access to this article is quite strange. A subscription to the journal is free, but if you want to look at any article online, then there is a pay-per-view charge. So plan ahead?

[2] His issues are 1) is yellow a lower value than blue? 2) using ROYGBIV as an ordering scheme makes it difficult to pick out intermediate values 3) people can have a number of different perception problems with colors such as occur in optical illusions. #1) is easily addressed with a legend, #2) I will indirectly address above, and #3) is a valid point which the author addresses well (and I refer to in the body of the post)

[3] FEA (and all computer modeling for that matter) seem to me to be something that you either do or do not. If you try and do it part time, you will be a miserable failure. For me, I do not.

Just Wondering

If you've lived for even 2 decades on this planet you have already seen scientist sannounce that they have developed a cure for pretty much any disease known. Some have multiple cures available, and new promising therapies are always just around the corner. The fine print of the announcements is that the cure has only been proven in rats/dogs/rabbits...pick your favorite animal. Unfortunately, when the cure is scaled up to humans, something goes wrong. Most of us are quite accepting of this either because we 1) understand the complexity of the differences between lower animals and humans, and/or 2) we have seen the pattern repeated over time and have learned to recognize it.

This pattern however, never seems to occurs when there is environmental exposure to chemical or physical hazards. When lower animals are exposed to (quite often unrealistically high) levels of some chemical and then some degradation in health is found, the assumption is then made that the same can and must occur in humans.

In some cases, this is appropriate - toxins seem to cut across the board, although the LD₅₀'s can vary some, and as always, it's the dose that make the poison [*]. But in other cases where there is small exposure (pick any example of something leaching into food), shouldn't we question if such a mandatory link exists. Or are we so cursed that all the potential good cures probably won't work out when going from animals to humans, yet all the potential bad exposures and consequences are guaranteed to pass on up?

[*] Consider the toxin from botulism. It is pretty much the deadliest poison known, but when diluted considerably is used in botox injections.

On the Loss of the Usenet

Let's take a trip back through time, way back to the early days of computer connectivity, back before Facebook, Myspace, blogging, instant messaging, and even back before chat rooms. Bulletins boards, well I think that is going too far back, but somewhere in that gap between bulletin boards and chat rooms there thrived this entity formally called the Usenet (Wikipedia), but also called newsgroups or discussion forums.

It was a simple, text only system, broken into various specializations where people could post questions and then others would post answers, although in the political groups, it was more along the lines of posting a rant only to be countered by an equally strong rant from the other side. It was threaded which made it easier to enter a discussion and addess only 1 post of interest. The heyday for this technology was from the mid-90's until about 2000, although it still exists today. Google still track the Usenet (under the "Groups" link). There was a very good group on polymers but being unmoderated, the Usenet has fallen into a huge trash heap of endless spam and is now largely ignored. (Looking at the archive, postings have fallen from a high of not quite 500/month to less than 10/month, and as you may also notice, I contributed quite a bit to the group over the years.)

The whole point of this post is that the Usenet served a valuble purpose that has not been replaced. Discussion groups do exist, but they are nowhere near as active as the Usenet was, and they seem mostly to be filled with students looking for someone to do their homework for them.

I do miss taking a swing at the questions, and while I do occasionally get such questions from people who stumble upon this blog, they are few and far between. I'm going to try and set up a questions box on the sidebar and see if that can change things. If anybody knows a simple way to do this, I'd be happy to take any shortcuts - "Dang it Jim, I'm a polymer scientist, not an HTML coder!"

More Aspen Research Video Available

I've mentioned before my employer's channel on YouTube. There's now about a dozen videos that have been made over the past year, either as dry runs inhouse before ANTEC or at an all-day technical session that we did for the local SPE session. The former talks are more in-depth, the latter are introductions. The come complete with disclaimers that our legal department added! Never seen that before.

I've also never seen myself on video before, well I have come to think of it, but just in home movie type things, never a full technical talk. Quite a strange out of body (literally)experience. I have less hair and body mass than then too.

Quick Thoughts

A) The Chembark blog is finally back! If you were following it in an RSS reader, it looks like you may need to reset it.

B) It seems like the chemical part of the blogosphere has the summer time doldrums. Many bloggers are posting less and yet the readers still seem to be there - and desperate for anything to read. Case in point: my post from Tuesday - 10 Things I Wish I Would Have Learned in School - was posted to reddit chemistry and readership here soared. The hits that I normally get in 2 weeks all happened in 1 day.

Pity the Resin Purchasing Manger

I don't think I can write a better lead-in than this:

Back in the good old days, raw materials' prices typically only moved in one direction—up—and a manager was tasked with guessing the rate of increase and timing his orders to get ahead of the price hikes. That was then; now, prices for key raw materials fluctuate up and down, often dramatically...

(From Plastics Today)

It's certainly true. Watching resin prices on the last pages of each weeks' "Plastics News" is like watching the stock market. If you think you know what is going to happen, come back next year and wave your millions in my face.

When resin prices are rising, it makes sense to stock up at a lower price, but if they are falling, then just-in-time is the best option. The futures markets can be used as a hedge but only for those knowing what they are doing.

Gorilla Glass

There's been quite a bit of buzz this week about Gorilla Glass made by Corning. I think this article by R & D Magazine captures a lot of good info that is otherwise not found - how it's made, when it was first made (the early 1960's), and why it took so long to commercialize it (it certainly wasn't for a lack of trying).

There are also a number of videos available showing testing of the glass. The link just provided shows 3-point bending, hardness testing (while looking through the backside of the glass at the stylus) and a non-scientific impact test.

The article also makes the comparison with fiber optic glass, a material that also had a very long commercializtion interval. Sadly, I we don't see too many cases of an old, shelved technology finally seeing its day in the sun.

Glass is an interesting material, in that while the long range motion of the molecules is prohibited, there is plenty of short range motion, in particular diffusion, that can occur. Chemical tempering, as is done in creating gorilla glass is one example, but I've also have worked with glass-ionomer composites in which polyvalent ions from the glass diffuse out and bind the acids sites from polyacrylic acid.

Rolling Rubber Bands

Sometimes some seriously interesting research can be done with very simple materials. Some new research from MIT and École Polytechnique studies the deformation of a rolling rubber band[*]. The faster the band moves, the more it deforms. Eventually the opposites come together, stick and stop the rolling.

[*] You have no idea how hard it was for me to not type rubber binder. It just rolls and bounces off the tongue in a nicer way.

10 Things I Wish I Would Have Learned In School

Not stuff that would be more appropriately acquired on the job, but academic stuff that would have been helpful and appropriate during the school years. And let me be clear: I'm certainly not picking on my teachers and professors, most of who were quite good.

1. Solubility parameters - oh, oh so useful in understanding polymer dissolution (and I'm talking about far more than just the Hildebrand cohesion parameter).
   
2. When you need to talk to an electrical engineer about rheology, use "capacitors" and "resistors" instead of "springs" and "dashpots".
   
3. "The Scientific Method", but only so I would know how non-scientists think I work (4 years of undergrad, 5 years of grad school and never once was the term used).
   
4. Statistical process control, because it can be useful.
   
5. Designed experiments, because other people think they are useful and you need to know what they are up to.
   
6. How to effectively referee an article.
   
7. Polymer additives. Everyone understands the polymers, but without the additives, all you have is a lab curiosity.
   
8. That "IV" means inherent viscosity, not intrinsic viscosity. (The former is just a value generated by a QC test while the latter is directly related to molecular weight via the Mark-Howink equation.)
   
9. That PVA can be poly(vinyl acetate), poly(vinyl alcohol) or whatever combination exists between the two (the latter is made by hydrolysis of the former and the extent of hydrolysis can vary considerably)
   
10. That polymer chemistry, far from being dead, is more alive and robust than many fields of chemistry.

What's on your list?

Alkanes from Sugars

A tip of the hat to the Biopol blog for catching this one: The LS9 corporation has announced a biologal pathway to convert sugar into alkanes.

You can read the details at the other blog; I'm just thinking about the mass balances. Sugar is C_nH_2nO_n. Alkanes are C_nH_2n+2. Assuming the sugars are glucose (the cheapest feedstock), then n = 6. That means that for every molecule of sugar, 6 oxygen atoms are removed, and 2 hydrogen atoms are added (from where?). Additionally, carbon-carbon bonds are likely being made and broken as the headline refers to alkanes and not just hexane. Regardless, that is a fairly large conversion and lots of O₂ is being generated. It might well be used by the normal metabolism of the cells as well, but this byproduct is certainly harmless.

Gecko Adhesion

Smart Materials and Structures Journal has a nice review article on "dry adhesives" - the microstructured surfaces that show unusual adhesive properties. These are synethic copies of natural structures such as are most commonly assigned to geckos, but also exist with other animals [1].

As with many, oh heck, most adhesives, van der Waals interactions are extremely important. But another aspect often overlooked initially when studying these feet is that the materials are also self-cleaning, or at least, they still work even when exposed to "dirt". The dirt moves to the spaces between the posts/pillars/setae (pick your favorite term) and is out of the way. [2]

The current state of the art is summarized in the article and it is open access (with registration) for the first 30 days, so if you are interested, grab the article while you have a chance.

[1] You see the same type of name-calling with superhydrophobic surfaces being assigned to the lotus plant even though many other plants show similar behavior. I see it in the lady's mantle growing in my wife's gardens - Minnesota is just a tad too cold for lotus plants.

[2] This same dirt absorbing mechanism is a big part for the success of Post-It notes - they can be used and reused many times before showing a significant loss of adhesion - try that with masking tape or some other tape, especially on a lightly soiled surface. Post-It adhesive is not just any old weak adhesive, but a specially structured adhesive.

Image provided by Bjørn Christian Tørrissen

A New Side Page

I added a new page to this blog. Explaining what I do at Aspen Research can be difficult and won't ever fit into a single posting, so my (very) personal description of what we do is now available on a second page. You can click on the permanent "What we do and how we do it" link to the top left of this page or you can click here. The page certainly is my best description to date. I imagine that I will keep fine tuning it some over time, but not in any major way.

Backlash on BPA - Infertility Report

The biggest news on the BPA front this last week was a report linking exposure to male infertility. From England, the National Health Service (NHS) and the British Plastics Federation (BPF) have taken a swing back. The NHS noted

"...that the results were not statistically significant, the study design cannot show cause and effect and there was no comparison group of men who were not attending an infertility clinic....As such, the newspapers have overblown the significance of this research, which does not provide evidence that BPA causes sperm damage or poor sperm quality in humans."

The BPF said they are

"concerned that interest in Bisphenol A is reaching the level of a witch hunt with studies which have failed to provide reproducible results."

The "witchhunt" statement is certainly ringing true to me, what with BPA being blamed for such a wide, disparate range of symptom and conditions.

You can't do that!

...but sometimes you can. I was reminded this afternoon of something strange that I saw many years ago. This company was running polypropylene and wanted it just a little bit softer, more like polyethylene. Basically, they wanted a PP copolymer (propylene polymerized with a few percent ethylene), but they were too cheap to pay for it. So they did something that I would never had thought to do: added some PE pellets in along with the PP.

This is where every cell in my brain started screaming "You can't do that!" The two polymers are not compatible, they have different crystallization patterns and cells, there is no reason that anything good should have come from it, but somehow it did. I still do not understand it to this day, other than to assume that the added PE was in such a small amount to not cause a problem. Somehow it worked. The tensile properties were what they wanted. They were happy.

But that's not all that had challenged my ability to bite my tongue. There was one other offensive item: THEY DID THIS ON A SINGLE SCREW EXTRUDER!

A single screw extruder is a piece of equipment known for poor mixing capabilities. A twin-screw extruder would have been a much wiser choice, as the intermeshing screws are able to open and close volumes and thereby mix materials. For an analogy, think about using your hands to mix spices or herbs into ground meat. You can maybe get by if you use just one hand, but it will be so much more effective if you use two. And so it goes with screws in an extruder.

Again, somehow this all worked for them. Don't ask me how.

A New Option for Accessing Research - Renting

A problem every researcher faces is accessing published research. Most articles are only accessible by either subscription or a pay-per-view fee. Now there is a third option - "renting". I've only seen this at the AIP site, but for a fee much lower than the total purchase price, you can have limited access to an article, meaning you can

"Read full-text of an article for up to 24 hours for as little as $0.99. Rented articles can only be viewed at DeepDyve and cannot be downloaded, printed or shared. Basic DeepDyve accounts, which can be set up at no cost, come with 3 free rentals to allow readers to preview the functionality and presentation of rented articles."

Depending on the article, this could be useful, although I don't see that I would personally use it much. I can live without the printing/saving option most likely, but the 24 hour access would be the real challenge for me. There are very few articles that I look at just once. Even if I am using an article for a current project (as opposed to something that is of general value), I usually can't pull all the relevant details with just one look - I keep going back to articles as my knowledge advances.

You can find out more at the DeepDyve site.

From the Archives of Polymer Chemistry

The Journal of Polymer Science, Part A: Polymer Chemistry is making available the 20 most cited articles to ever appear within their pages. Looking down the list, there are a few that I can comment on:

1) This 1954 article discloses the discovery of the Flory-Fox equation: T_g = T_g,∞ - K/M_n. The work was originally down with polystyrene, and guessing from the age, the fractions were probably prepared by the labor-intensive fractional precipitation procedure - pity poor Mr. Fox for being the grad student undertaking that!

2) There also a 1956 article by Dr. Natta of Ziegler-Natta catalyst fame. I don't seen the research as being ground breaking as it was only the polymerization of 1,2 butadiene.

3) More recently is the 1973 paper with the name Hideki Shirakawa attached. The paper is on the polymerization of polyacetylene of high enough molecular weight to form films. Polyacetylene was the first inherently conductive polymer and Mr. Shirakawa won the 2000 Nobel Prize in Chemistry for this (and follow up) pioneering work. Polyacetylene had been previously made prior to this publication, but I think this is the first time that a high molecular weight had been prepared, in this case because MR. Shirakawa has miscalculated the amount of catalyst needed and added 1000x the normal amount.

Other papers are review as would be expected. Review papers always collect high citation counts. The remainder of the papers do not have any significance to me. Anyone?

Another Massive Chemical Plant in Russia

Following up on the opening of the world's largest PVC plant, Sibur is now putting together a large PP plant (I know, I know, all PP plants are large), this one being built in an even more remote spot - Tobolsk, Siberia.

Just getting the parts there is a challenge. It not so figuratively involves moving heaven and earth:

"Two 60 tonne, 38 metre-long slag purging columns were shipped by via the Indian Ocean and Suez Canal and overland through Europe to St. Petersburg, Russia, prior to delivery to the site.

...The biggest unit still to come from South Korea is a massive 1,000 tonne, 100m long propane dehydrogenation column which is destined for the Russian port of Arkhangelsk. From there, the 10m diameter column will travel by special barge up the River Irtysh to dock at the port in Tobolsk, which has been specially dredged and expanded to take the largest project equipment."

As with most PP plants, these are built close to the supply of propylene, so I won't question as strongly the location of this plant, but the way that Sibur is expanding their polymer capabilities, it makes you wonder if there wasn't a very recent remake of "The Graduate".

Invista

The Urethane Blog had a couple of posts last week that make an interesting juxtaposition:

First, they are hiring: "Invista Hiring at US Lycra Plant" Good. Jobs are always a good thing.

But then those jobs might not be around for long, as a mere two minutes later, the blog posted a PR blurb that they are considering selling: "Invista considers selling North America polymer and resin assets". There's no assurance that the new jobs would be on the block, but it still seems like a risk to be avoided if possible.

Comments

As you might have guessed by the few postings I made last week, I was on vacation, which in itself was somewhat adventuresome - I might post about it at some later point.

As expected, there were numerous comments that were being held for my approval before being shown, and all but one were summarily deleted with extreme prejudice. This one I kept and am posting so that all may see the creativity of the individual. I modified the comments just slightly so that it would be safe for the work place.

"HELP! I’m currently being held prisoner by the Russian mafia xyzrxyz [url=http:// a link to a site selling sugar pills that you hope will make certain parts of you bigger.com] xyzrxyz and being forced to post spam comments on blogs and forum! If you don’t approve this they will kill me. xyzrxyz [url=http://a link to another site selling sugar pills that you still hope will make certain parts of the male anatomy bigger.com] xyzrxyz They’re coming back now. xyzrxyz [url=http://a link to a third site that... you get the picture] xyzrxyz Please send help!

Needless to say, I am not planning on sending any help, and even if I were, the commenter didn't bother to say where to send it. Too bad for this guy.

I'll get back to the regularly expected postings pretty quickly.