Tuesday, December 15, 2015

1,000,000 Pageviews

Sometime in the last few minutes, the all-time number of pageviews for this blog made the quantum leap to 7 figures.
(Ok Mom, you can stop clicking on random internal links now). If I only had a nickel...

Since it took just over 9 years to get this far, I project it will take about 90 years to get to 8 figures. Looks like I ought to seriously start exploring life extension options.

If you were perchance on of that 1,000,000, I express my sincere thanks to you. I'm deeply honored that anyone wants to read what I write.

Reinventing the Wheel (only this time it's a biodegradable plastic!)

While I've always been of the opinion that biodegradable plastics will be limited to very specialized niches, others don't always feel that way. Take Marieke Havermans of the Netherlands. A former packaging designer for Heinz (as in ketchup), she recently discovered an unrecognized application for biodegradable plastics. As reported last month by Plastics Today:
"When Marieke Havermans’ mother-in-law died, the family was given a catalog to browse through by the funeral home from which to choose the casket they wanted. 'Each and every one of them was basically dark, ugly and too expensive. For the most part, they were made of particleboard that was lined with leak-proof paper—which was not what we were looking for,' she said. 'Particleboard is a cheap construction material that emits formaldehyde. There’s no dignity in particleboard.'

Havermans was convinced that there had to be a better way. Her idea was simple: 'Why not design a sustainable casket made of a natural bioplastic that would, in time, simply biodegrade? A casket that would not only impact less on the environment, but that would also be an attractive and affordable option for everyone,” she explained.'
So she got together some polylactic acid (PLA) and some reinforcing fibers and voila! created a biodegradable plastic casket.

I'm not sure that I see any "dignity" in PLA, but maybe others do. Further, PLA is only considered biodegradable in an industrial compost site, which is not the same thing as a cemetery.

Another sticking point is that here in the US, the use of concrete burial vaults is very common. The bottom of the vault is placed in the ground first, the casket is placed inside the vault and then the concrete lid is placed on top. The reasons for use of burial vaults aren't exactly clear. Possible reasons are to prevent the ground from sinking over time as the casket degrades. Or because it slows the degradation of the body in case it needs to be exhumed for a criminal investigation. Or (cynically), because someone wanted to make more money than just selling caskets and burial lots.

Regardless of the reason, the near ubiquitous use of vaults will probably prevent these caskets selling well here in the US. But there is one other reason that I don't see them selling well (and why I have to laugh at the idea of this casket): it's because biodegradable burial caskets have already been in use for hundreds/thousands of years. They are called "pine boxes":
A pine box casket - and it's biodegradable!
Reinventing the wheel I say. That the wheel is justified by marking it as "biodegradable" when other traditional options are too is scamming people when they are emotionally vulnerable.

Previous Years


Monday, December 14, 2015

Time for a Cage Match

Apologies to the fans fan of this blog (Hi Mom!) for not posting in such a long time. Between Thanksgiving and winding up the school term, it's been pretty haywire. But the final exam has been written, (not proctored - that comes Wednesday) and then it's just a matter of final grades, although I am taking advantage of the break to start working on lecture notes for next semester.

But I have a great welcome back item - the announced merger of Dow and DuPont. Both of these companies have a lot in common. They are both huge. Their names both start with the letter "D". And they both have had to put up with activist investors in the last year or two.

Dow was the first to be attacked from "within", in this case by Daniel Loeb (1, 2, 3, 4, 5 and 6). That all ended when Dow and Loeb and declared a truce just over a year-ago. In a classic case of monkey-see, monkey-do (a phrase that in this case insults monkeys, even really dumb monkeys), Dupont was then attacked from within by Nelson Peltz (1, 2, 3 and 4) before finally losing his proxy battle.

But both of these guys are still hanging around the picture, which then raises the biggest question in my mind about the merger: which activist investor will be the top dog afterwards? Everyone is far more concerned concerned about government approval for the deal, but what about the undercard: Loeb vs. Peltz? As big as this new company will be, it still will not be big enough for these two mega-egos. One of them will have to go.

My proposal: a cage match!
Steel cage match - Loeb vs. Peltz?
Which company had the better activist investor? This would be the once-in-a-lifetime chance to find out. Imagine the pay-per-view revenue. Wall Street bankers, financiers and countless C-Executives (especially ones previously harassed by these two) would pay thousands to watch this. Mayweather vs. Pacquiaou pulled in $410 millions - this could double that and give me enough cash that I could become an activist investor! The bookies would have Loeb as the early favorite as he is a sprite 53 years (turning 54 later this week) while Peltz is almost 20 years his senior, but when big money like this is at stake, these guys would be as ferocious as 2 emaciated tigers fighting over a fattened lamb.

"Grace, get me Loeb on the phone right away. Oh, and start dialing up that Peltz guy too. We're going to do lunch..."

Previous Years

December 14, 2012 - Changes. Big Changes.

December 14, 2011 - Isolating Thixotropy from Shear Thinning

December 14, 2010 - Will the Supreme Court become Probabilistic?

December 14, 2010 - Epoxy Resin Drop as Art - and Rheology Puzzler

December 14, 2009 - LyondellBasell to go East?

December 14, 2009 - Thermal Hystersis

Thursday, November 05, 2015

A Frisbee (Murder) Mystery

Fellow (retired) blogger Eric F. Brown brought to my attention an article about Frisbees, in particular, the Frisbees used playing Ultimate Frisbee. It become apparent pretty quickly in the article that the participants of the sport take it extremely seriously.

To me, a Frisbee is a Frisbee. I grew up with the Wham-O brand, but probably because there weren't any other brands to choose from. That has changed, and worse yet (for Wham-O), they are no longer the top dog. Or even the number 2 dog. And apparently, Wham-O is to blame for their own problems, and it's all because of the additives that they chose use. White Frisbees were traditionally made white by the addition of titanium dioxide. TiO2 is a great white pigment as it has great hiding power and you can add lots of it without it showing signs of yellowing (unlike, say calcium carbonate). But it is expensive and so people are always looking for alternatives.

And Wham-O found an alternative set of additives:
Comparison of Wham-O Frisbee Additive Packages
I'm not sure what type of analysis this is other than poorly done. This shows the titanium dioxide as just titanium (What type of instrumental analysis can't detect oxygen?) So while it's tempting to assume that the other metals are probably oxides as well, the aluminum is more likely to be aluminum hydroxide, a common white pigment. I can't believe that silicone was ever added (as opposed to silicon, and probably the oxide at that). The zinc could be either the oxide or the sulfide (more on this in a minute). I can't see that iron oxides would ever be used (that bloody red color is not too appealing in most applications). And what's this "other" category? (Seriously, who did this analysis? Whoever paid for it got taken good.)

Regardless, the new additive package was not accepted by the players:
"At the time, Titanium Dioxide was getting pretty scarce. So the [Wham-O] people in Mexico, when they were molding the discs, they put in some Aluminum Oxide and other fillers, instead of straight [Titanium Dioxide]. I don’t know how much you know about polymer chemistry, but the other additives were aggressive and they actually caused some degradation of the plastic and loss of performance."
Plastic degradation? Now that get's interesting. Which brings us back to the zinc. We don't know what form the zinc was in - elemental (probably not), sulfide (a white pigment, but not the greatest and it is somewhat pricey) or the oxide (another white pigment). Zinc oxide is my guess, as it is photocatalytic under mildly acidic conditions (pH ~5.5) which would lead to the degradation state. Going from 8 % zinc to 10% zinc isn't going to make that big an impact - but that's assuming that the zinc was the oxide in both formulations. What if the initial formulation was zinc sulfide while in the new formulation it was zinc oxide? This analysis can't tell the difference, so it's entirely possible and it fits the limited data.

Sadly, based on this poor analysis, we'll never know but that is my guess: the TiO2 gets the blame, while the ZnO skates free for the killing of the Wham-O Frisbee business. It's a miscarriage of justice.

Previous Years

November 5, 2012 - Job Titles and Business Cards

November 5, 2010 - Flow-Induced Crystallization

November 5, 2009 - Public to Private and Back Again

November 5, 2007 - Negative Intrinsic Viscosity and Positive Intrinsic Viscosity

Tuesday, November 03, 2015

A Novel Polymer Curing Technique

To update an old expression [*], there is more than one way to cure a polymer. The use of heat and UV-light are quite common; visible light can be used as can e-beams; moisture-/oxygen-curing are options; you could argue that 2-part silicones or urethanes are cured upon mixing (a chemical cure); and there are a few more options that escape me at the moment. Back in August however, researchers announced a new curing technology - this one is based on electricity (Open Access article).

It's one of those "why didn't I think of that" papers, although in my case, as much as I hated electrochemistry, I have an out.

The researchers used 3-[4-(bromomethyl)phenyl]-3-(trifluoromethyl)-diazirine as their crosslinking agent, due to its formation of free radicals in reductive electrochemistry. Once the free-radicals are formed, then we are in a common realm for polymer chemists and my comfort level returns. Take a look at the mechanism:
Electrocuring mechanism
The aryl-carbene can react with any of a number of atoms for crosslinking.

One limitation on this technology is pretty obvious - it is restricted to curing between conductive substrates. (Metals, indium-tin oxide coated surfaces such were used here, inherently-conductive polymers...) But what is far more concerning with this particular curing agent is that it generates N2. Gas generation in a polymer matrix is usually not desirable (unless you are making foams). It's only 1 mole per mole of diazirine, so the total amount is limited since crosslinking agents are seldom used at high levels. But still...

I recognize well that initial discoveries are seldom without issues, so consider this criticism of the nitrogen generation as a setting a direction for the mandatory "future research". But since it will involve electrochemistry, feel free to go ahead without me.

[*] That expression being "There's more than one way to skin a cat". The origins of it aren't entirely clear from what I can find online, but the meaning is: there's more than one way to get a job done. Despite the literal reading of the expression being quite gruesome, it is quite commonly said indicating that no literal intent is intended.

Previous Years

November 3, 2008 - Viscoelasticity Movies

Thursday, October 29, 2015

Dull-and-Boring News Items

Sometimes dull-and-boring is good, sometimes it is bad. Here's an example of each regarding recent news items about Dow Chemical:

1. Their latest earnings continue to look good. I especially like the poke that this article takes at the activist-investor Daniel Loeb. He's still around? When is that guy going to take his ball and go home? Regardless, a profitable earnings reports is dull, but good.

2. The Dow chemists have been working hard and have developed a new plastic for Dow to sell. With as many chemists as Dow has, you would expect it to be some gee-whiz polymer with potentially mind-blowing chemistry and great potential to replace non-plastic materials with plastic. So what is it? An LLDPE (linear low-density polyethylene). LLDPE is actually a comonomer of ethylene and α-olefins. LLDPE's have been around for decades so this is hardly exciting or novel. But as the article notes, Dow's last major product introduction was in 2013 and was also olefin-based. What else would you expect when your former Chief Technology Officer goes on the record saying that "...[no] new polymers would be discovered, since chemists already had done a thorough job in finding ways to link carbon, oxygen, hydrogen, nitrogen and sulfur atoms."

This definitely is in the dull-and-bad category. Hopefully the current CTO has a better outlook on product development.

Previous Years

October 29, 2014 - Comparing Burger Chains and Oil Companies

October 29, 2013 - A New Chemistry Lab Building, But Without New Chemistry Jobs

October 29, 2012 - More Open Access articles in Polymers and Rheology

October 29, 2010 - Garbage Patch Vacuum Cleaners

October 29, 2010 - Good Advice

October 29, 2010 - UV Scale-up

Wednesday, October 28, 2015

Elemental Sulfur as a Monomer

It's been far tooooo long since I commented on a research article, but it's time to change that. Angewandte Chemie has an open access Early View article on a new elemental sulfur/limonene polymer. The researchers are from Flinders University (South Australia) and the research has received quite a bit of press since it is able to capture mercury ions (Hg2+) from water, and as a bonus, changes color it does so. A further bonus is that sulfur is a waste product of the petroleum refining industry and limonene is a by-product of the citrus industry, (although somewhat more valuable than elemental sulfur).

The reaction is straightforward:

Simply melt the sulfur, add the limonene and wait. The sulfur rings upon heating break apart and form thiyl groups which react with the unsaturated bonds in the limonene. This is remarkably similar another sulfur/organic copolymer ($) that I blogged about 2 years ago (1, 2), which took the same approach of heat and dump. In both cases, the unsaturated organic compound needs to be low enough in volatility that the hot sulfur (> 170 oC) doesn't evaporate too much of it off.

As is shown above, there are stretches of sulfur-sulfur (sulfide) bonds between the organic segments, and these are what capture the mercury (hence the old name for thiols of "mercaptans"). I did find it somewhat surprising that the amounts of sulfur:liminone were 50:50 on a mass basis.
"An equal mass of sulfur and limonene was chosen to maximize the content of both industrial by-products in the final material."
The authors themselves note that sulfur is produced at nearly 1000x the rate of liminone, so maybe trying to incorporate a little more sulfur would be a good idea. Additionally, the formula weight for liminone is 136 g/mol while that of sulfur (S8) is 256 g/mol, which further skews the ratio of the comonomers towards the limonene.

I also wonder how long researchers are going to keep running these reactions in open flasks. The engineer in me is makes it really difficult to not scream at the monitor about running the reaction under pressure so that the volatility would no longer be a concern. Or maybe in a twin-screw extruder, for continuous production of the polymers. That would make for a great patent, wouldn't it. Or maybe I should say "would have"...

Previous Years

October 28, 2013 - SoBe, What Were You Thinking?

October 28, 2010 - A Foreign Body

October 28, 2010 - Is this safe to eat?

Tuesday, October 27, 2015

Fairlife Followup #2

Back in July I wrote about the non-recyclability of the container used by Fairlife for their chocolate milk. The recycling code says "#7 PETE" which is problematic since PETE is #1 and "Other" is for #7. Since I didn't know how to sort it, it went into the garbage. I email went off to Fairlife to explain themselves, but their reply only muddied the water further, stating that a white pigment in the PETE made it a #7. That's not right since pigments do not affect the recycling codes for any other plastic. I speculated that there was likely a barrier layer that made the container a #7.

It looks like I was right. A person [*] with access to some lab equipment cross-sectioned the container and found this:
Fairlife Milk Container - Cross-Section

Busted! There is a barrier layer in there. The identity of it is unknown, but ATR-FTIR did show the 2 main layers to be PET.

So it's time to send another letter off to Fairlife. Hopefully I'll get a more truthful reply (and not so many words in ALL CAPS!).

[*] Note: the person who did this analysis wishes to remain anonymous. I will respect that request and am very grateful for their contribution.

Previous Years

October 27, 2010 - The Coolest Thing You Can Do With a Polymer - Set Yourself Ablaze

October 27, 2010 - How to Get Around FDA Regulations - Legally!

October 27, 2008 - So when are they going to ban Scotch Tape?

Thursday, October 22, 2015

King Tut is cutting down on his BPA exposure

Earlier this year it was announced that King Tut's iconic death mask had been damaged by some incompetent curators - the beard had been knocked off! - and then hastily repaired using epoxy that ended up getting everywhere. My take at the time was that the epoxy most likely contained BPA (bisphenol A) and thus the mask was being exposed to BPA for all eternity. But that concern is now being addressed, as a German expert has been assigned to repair the mask [*]. Since the depth of penetration of the epoxy is unknown, the time for the repair is vague, with 2 months being the outer limit at present.

Apparently the construction of the mask is unknown (other what is on the surface) and so the repair team will take advantage of this opportunity to study it further. The details of the construction will then drive what approach will be taken to reattach the beard in a more suitable manner than the "Dumb and Dumber" approach taken last time.

I can't imagine what would be done to reattached the beard. A mechanical approach would stand up the longest and duration has to be a great concern. After all, this object will be retained for millenia into the future and adhesives - organic, silicone or any other chemistry - will not have that durability. If they are used, it would likely be with the view that any adhesive would have to be removable at some future date so that it could be refreshened. (No more scraping off epoxies with a wooden stick.) But a mechanical approach would also be the most invasive and damaging, even if the outer aesthetics are immaculate.

It possible that some good may come from the epoxy disaster. If epoxy did in fact penetrate the mask to some degree and then hardened, that material could then serve as a barrier to penetration from adhesives applied now and in the future. And that could put the adhesives option back on the list. We'll just have to wait and see what is approach is decided upon and what the justification is.

[*] How do you get a job like that? Is it a free-lance position and what are the hourly rates?

Previous Years

October 22, 2014 - Dow Chemical's Earnings Keep Improving

October 22, 2013 - October 22, 2013 -

October 22, 2012 - White Isn't Always White

October 22, 2010 - Thoughts on Losing Electricity

October 22, 2010 - Plastics - They Have a Future, but no Futures

October 22, 2010 - It's Not Easy Being Green

Tuesday, October 13, 2015

Choosing Biodegradable Polymers for a Research Topic?

The topic came up this morning about what would be a good area to research for a Ph.D. nowadays. It was suggested biodegradable polymers, but I really dislike that area immensely. Biosourced polymers would be much better.

Biodegradable polymers have their uses, particularly within medical applications, but as a general commodity plastic, something to take on the Big 6, they will be inherently problematic. Inherently. As in you cannot avoid the problems. To most people, biodegradability is a way to address pollution problems, but biodegradability is not an effective solution because a polymer will never biodegrade the instant it is released into the environment. Look at paper, a readily biodegradable material, but even paper doesn't biodegrade instantly. Paper products are a very visible type of pollution. Do crews cleaning up along highways, in parks and other public places pick up paper or do they leave it because it will biodegrade? Of course they pick it up. When you see paper products spread across a field, are you happy and not concerned because there really isn't a waste problem since it will all biodegrade and take care of itself?

The minute any waste is released into the environment, it becomes pollution. Biodegradation is a long-term solution to immediate pollution, which means it isn't a solution at all. And while research on biodegradable polymers is not without merit, it is inherently limited in its potential to help civilization. No one has proposed or has even imagined creating a material that is smart enough to know when it should and shouldn't biodegrade, let alone one that would be able to biodegrade almost instantly once that decision is made. These are inherent limitations to biodegradability.

Biosourced polymers are quite different. Instead of being made from petroleum, they are made from bio-based feedstocks. For examples, Braskem has developed a process to make polyethylene from sugar cane. The sugar is fermented to yield ethanol, the ethanol is dehydrated to produce ethylene and then the ethylene is polymerized. You now have a bio-based polymer that is (nearly) identical to the petroleum-based polymer (the only difference being the presence of the C-14 isotope). And so the search is on for creating bio-based sources for the monomers currently used in making polymers. And the search is also on for identifying new, biosourced monomers that have been too difficult/expensive to produce from petroleum and that can be used to create novel polymers. Examples are various types of furans and isosorbide. Some of the resulting polymers could be biodegradable if you really are obsessed with that tact, but being biosourced does not mean that they are automatically biodegradable. (Bio-source polyethylene is just as non-biodegradable as petroleum-sourced polyethylene.)

Speaking strictly from a practical viewpoint, biodegradable polymers would not be my favorite subject to study in school because of the time-scale of the experiments. Once you have made your new polymer(s), testing for biodegradability takes weeks and months to perform. That's weeks and months before you get any feedback to let you know to stay-the-course or try something else. Industrial researchers can work with those time scales, but as a student? No way. Unless you want to take a decade to get that Ph.D.

Previous Years

October 13, 2014 - Dinosaur Mode

October 13, 2010 - Calling Mr. Murphy...

October 13, 2010 - Pushing the Laws of Science and Man

October 13, 2010 - Never Mind

October 13, 2009 - Diodes, Diodes Everywhere

October 13, 2008 - Another Unusual Water Soluble LCST System

Tuesday, October 06, 2015

DuPont's CEO Wins the Proxy Battle, But is Leaving the Company

In much the same way that great revolutionaries seldom make great post-revolution leaders, CEO's are usually incapable of leading a company through more than one set of issues. Great turnaround artists don't work well for maintaining steady, long-term growth. The same goes for great acquistionaries, great sales-increasers, etc. The most recent example of that is Ellen Kullman, whom PlasticsNews is reporting to be leaving the CEO position of DuPont, having spent much of the year fighting of a stupid proxy fight, (probably the stupidest one I've ever seen). While she won the battle quite handily, she doesn't seem able to handle the new challenge.

Earnings for the chemical giant have been lowered for the coming year in large part due to the stronger dollar. This is an issue that CEO's from all international companies have to deal with. Those with a financial background can better handle these types of issues. Being an engineer by training, this is something that is probably out of her league (heaven knows I would be just as unqualified.) Whether the board asked her to step down or she initiated it is unclear and may never truthfully be known. But we can be certain of this: plenty of ink will be wasted on contradictory articles supported by anonymous sources as each side attempts to spin, counterspin and outspin the other. (Just don't expect me to cover it.)

Previous Years

October 6, 2010 - A Rare Case where a Misnomer Might be Good Thing

October 6, 2010 - Sun Chips to Pull It's Noisy PLA Bag

October 6, 2009 - The Dog and Pony Show

Monday, October 05, 2015

Nobel Prizes and Polymers

This year's Nobel Prizes are being announced this week. The Chemistry Prize is announced on Wednesday and I doubt that it will go to anyone researching polymers. Since the first prize was given out in 1901, only 4 times has it been given to polymer scientists: Staudinger in 1953, Ziegler/Natta in 1963, Flory in 1974 and Heeger/MacDiarmid/Shirakawa in 2000. You could argue that polymers were never in the running in 1901, as it was only in the 1920's that Staudinger began his crusade to have polymers recognized for what they are - macromolecules and not just colloidal associations as others would have argued. In that case, there were only 62 chances to win since 1953, so the odds are quite a bit better than they originally appear. (Coincidentally, only 4 women have also won the Nobel Prize in Chemistry, but that is a different discussion for another day.)

But regardless of the exact calculation, the slim number of prizes reinforces my long running argument that polymer chemistry is just a small fraction of the world of chemistry. Arguments that half chemists work in polymers have no merit. I ran some numbers earlier this year and came up with 8% or so as a more realistic number. This number in fact correlates rather well with the number of Nobel Prizes (4/62 = 6.5%).

Whoever does win, I do hope that their research can be easily explained to freshman. I have a whole class full of them and being able to include this as enrichment material on Wednesday morning would be wonderful. It's been a good year for making tie-ins with current events. The timing could not have been better for ytterbium to be reassigned a new atomic weight, since I had just been lecturing about how the fractional abundances of isotopes contribute to atomic weights, and suddenly there was this real world example. Similarly, the discover of flowing water on Mars (on the basis of sodium-/magnesium perchlorate) was perfectly timed with a lecture on electrolytes in water (thank you NASA!). So if the people in Stockholm could give me a heads up so that I have time to adequately prepare, I would appreciate it.

Previous Years

October 5, 2010 - On Units of Measure

October 5, 2010 - Plasticizers = Positive Drug Test?

October 5, 2009 - Duplicity and Siloxanes

October 5, 2009 - Public to Private and Back Again

Wednesday, September 30, 2015

Microbeads as a Solution to Pollution?

(Thanks goes to Eric F. Brown for bringing this article to my attention.)

This might not be turning lemons into lemonade, but it could be close. Microbeads have recently become the cause de du jour for environmentalists fighting plastics in the oceans and other bodies of water, but a UC Santa Barbara researcher looks upon the beads as a solution and not a problem. By putting a carefully selected peptoid [*] coating on the beads, the beads can bind hexavalent chromium and remove it from water. Hexavalent chromium is the particularly nasty version of the metal made famous by the movie Erin Brockovich and is in the drinking water of cities as large as Chicago.

While hexavalent chromium ions are a worthwhile and newsworthy target, I imagine the technique could be applied to recovering other ions/elements as well. Arsenic is a problem in many parts of the world as are other metal/metal ions. And I can't see any reason why any particular bead wouldn't be able to recover multiple metals (although a mixture of beads targeting each individual metal could work too).

The article raises but doesn't answer the question of recovering the beads. Making the beads around a magnetic core would be a quick-and-easy option to allow for recovery, but buoyancy would be a concern. Smaller cores would help that, but then a stronger recovery magnet would be needed. Increasing the thickness of the polymeric shell would increase the buoyancy, particularly if it was foamed to any degree. But even if the whole concept of using microbeads fails, the peptoid coatings could still be used to coat other materials to reach the same end. Peptoids are apparently quite resistant to hydrolysis, which is crucial for application like this, so it's just a matter of finding an acceptable substrate with a large surface area and possibly sufficient porosity so that this doesn't end up as a giant filter removing the good (sea life from microbes on up to whales) as well as the bad.

[*] Peptoids are like peptides, oligomers of amino acids, but amino acids have their substituents on the α-carbon, while for peptoids, the substituents are on the nitrogen.

Previous Years

September 30, 2014 - A Mixing Demonstration using non-Newtonian Blue Maize Flour Suspension

September 30, 2011 - Now that we have the "Perfect Plastic", you don't need me

September 30, 2011 - The Research behind "The Perfect Polymer"

September 30, 2010 - Pyridine

Monday, September 28, 2015

Peer Review Week - How to Find Industrial Researchers [*]

Today is the start of international "Peer Review Week", a time to celebrate all the good that comes from peer review and to make sure that it receives its proper recognition as playing a key role in publishing research and awarding research grants. Blame it on my grey hairs for being jaded and cynical, but I expect all the commentary to focus on academic researchers performing peer review and either giving industrial researchers short shrift or no shrift at all.

Being until recently a non-academic researcher, (being an adjunct professor I am no longer so pure and pristine, but as I only lecture 3.5 hours a week, I spend far more time being non-academic than academic and so still relate more closely to non-academics), it goads me to no end to be ignored and otherwise taken for granted. Just this year alone I've already reviewed 14 manuscripts, and have not submitted any for review during that time (0 submissions is very common output for industrial researchers). You can't even take a proper ratio on that, but clearly as an industrial, non-academic researcher, I am contributing to the system greatly in excess of what I get out. Even if I had only completed 1 review, since I didn't submit a paper for submission, the system still would record me as a positive contributor. And that is how most industrial researchers are. We very seldom contribute manuscripts for publication, so we don't tax the system highly. Even for those researchers that do submit a manuscript or two a year, it wouldn't take much for them to pay the system back.

All of which is background to this: I got into a snit this morning on Twitter when someone tweeted about how valuable industrial researchers are to peer review, but they are "...more difficult to find (email/position only seldom listed in www)". So here are my suggestions to editors everywhere on finding industrial researchers that can help with peer review.
  1. Start with LinkedIn. It's like Facebook, but for professionals. There are countless professionals (about 200 million give or take) from all fields on it, they can be easily searched and emails/websites are readily available. Even if they aren't explicitly listed, as long as their employer is named, you can find them. There are two ways:
    • You know how every new phone comes loaded with pre-installed apps that you will never use and you can't get rid of them? Well, you're going to use one of them. There is this app on cellphones called the phone feature (I believe that this is where the name "iPhone" comes from!). Use it to call the main number for their employer (which you can easily find on the internet). Ask to be connected to the employee. It may take a little bit of time, but companies don't really try to make their employees miss out on calls from the outside world.
    • If the phone is too scary, email them. I know your response already ("BUT I DON'T HAVE THEIR EMAIL ADDRESS!"), but it isn't difficult to figure out a work email address. While personal email accounts can be difficult to guess, corporations like to give the appearance of transparency so no sneakiness is allowed. My work emails have always been some variation/combination of my last name and then first name/initials/... @companyname.com. Over the years, I've had jaspevacek@mmm.com, john.spevacek@aspenrearch.com, etc. Once you know the pattern that a company uses, you're practically there. Suppose you want to contact Elmer Fudd at 3M. There are only 26 possibilities: start with eafudd@mmm.com, ebfudd.com...ezfudd.com. For more common names such as John Q. Public, you might need to try jqpublic1@mmm.com, jqpublic2@mmm.com...I'm sure someone could write an app to auto-generate all the possibilities. All you need is to know the format that the company uses. And that's easy to figure out since sites like this have done all the work for you.
  2. Now that you have captured your first industrial researcher, treat them like a spark and build a massive fire off of them. Ask them who else they know and could connect you to. Build a network off of these people and keep expanding it.
Was that so difficult? I realize this is pointed and snarky, but that Tweet this morning really got to me. I've been writing for years about how industrial researchers are seriously overlooked as a potential source of manpower and for someone to complain about difficulty in contacting us was just unnerving. And while the RSC was ahead of the curve in contacting me years ago to be a reviewer (they got my email address off of this blog!), they have never bothered with step 2. Their loss. For Peer Review Week 2015, let's make this the year that industrial researchers are finally recognized as a vast, wasted resource that they are, and then start to use them. [*] Clever people will take these techniques and put them to other constructive uses.

Previous Years September 28, 2012 - The Largest Molecule September 28, 2011 - Hidden Problems in Heat Transfer September 28, 2010 - Blur, perception and Distance >September 28, 2009 - Marketing that anyone can love

Thursday, September 24, 2015

Rubber bullets are (usually) not lethal, but these new plastic bullets are

The website-with-an-obvious-viewpoint, BearingArms.com is reporting that polymer bullets are under development. The bullets are actually a polymer/copper composite (no idea of what the relative amounts of each are), but since they have less mass than a traditional round, there is less recoil when fired. But more interesting than the materials is the shape of the bullet. Take a look:
Plastic Bullets
They are rounded in the front (like many other ammunitions), but also scalloped in three locations. This design was not accidental (few designs ever are) and testing on ballistic gel has shown that this feature increase the lethalness of the bullet. Go to the article if you want the details; they are not appropriate for this column.

This opens the door to future designs that are even more "creative", since working with plastics is generally much easier than working with metals. And since we already have 3-D printed guns, it won't be too long before we have 3-D printed bullets too.

Previous Years

September 24, 2013 - Here's Research to Lift Your Spirits

September 24, 2012 - Bird-Brained Rheologists

September 24, 2010 - Biorenewables

September 24, 2010 - A Substitute for Aqua Regia

Tuesday, September 22, 2015

Faking Plastic Currency

Canada introduced polymer currency back in 2011 in part due to their increase longevity compared to traditional paper currencies, and also in part due to the increased difficulty to counterfeiting. But that time is over. CBC News is reporting that fake C$ 100 are popping up in Regina, Saskatchewan. Take a look at the fakes (on top) and the real bills (on bottom):
Real and Fake Canadian Plastic Currency
The images are pretty well done; the only glitch is the silver tape (probably a vapor-coated aluminum PET) that was used instead of the clear holographic tape.

Somewhat ironically, this is the most science/technology oriented bill that Canada issues. The distinguished gentleman is Sir Robert Borden, a former Prime Minister (I had to look it up as my knowledge of Canadian PM's is limited to Trudeau and I couldn't pick him out of a police lineup), but there are also "stock" images of a women with an optical microscope (looks like it might even be a polarizing model), an EKG scan, the obligatory DNA double-helix and a vial of insulin.

But why the C$ 100 bill? Why not a smaller denomination like a 50 or a 20? A 100-dollar bill is likely to gather attention and closer inspection that a 20 and a 50 won't. 20's are standard issue from an ATM (although 50's are becoming more and more common) so people are unlikely to pay as close of attention. Unless the counterfeits are really that difficult to make so that the extra large denomination is the only way to make counterfeiter's scheme payoff, someone making smaller denominations could go on for a much longer time span before getting attention (and ultimately detention!).

Not having a criminal mindset, I don't know and never will.

Previous Years

September 22, 2014 - Back from Vacation

September 22, 2011 - Another Source of Ocean Plastics - Your Clothing

September 22, 2010 - Watch out all you Grandparents!

September 22, 2009 - Self-Healing Plastics

Tuesday, September 15, 2015

Academic Patents vs. Industrial Patents

I've read a lot of patents (too many patents) over the years and have seen plenty of good ones and plenty of bad ones. A good patent will be based on an unexpected result, a true discovery instead of an incremental improvement in an existing field. It's usually pretty easy to show that it is a true discovery when you can find literature suggesting that your discovery will not work. Even better yet is when the literature explicitly states that your discovery will not work.

Bad patents on the other hand, exist for any of a number of reasons. They can have extremely narrow claims, they can be flat-out wrong (bad/unreliable data, goofy conclusions from the experiments, etc.) and they can be overly descriptive and provide too much information. It's this last category that I want to talk about today and the authors of such patents. My experience has been that they are almost always written by academic researchers and not industrial researchers.

Consider this recently published application that looks more like a research paper than a patent application. While it is a joint invention of researchers at Northwestern University and Dow Chemical, you can tell that the application was based on a paper that the Northwestern researchers had written for publication, only to later shoehorn it into a patent application. It describes a new catalyst for non-isocyanate containing polyurethane systems, an interesting area since isocyanates exposure can lead to some serious health issues. But the application contains way too much information, lots of which is irrelevant to obtaining approval for the application. For instance, Figure 3 shows the reaction kinetics:
Reaction kinetics for isocyanate-free polyurethanes
The text further explains that the lines are from second-order kinetic model and has values for the reaction constant and the activation energy. Figures 4 and 5 (not shown) have DSC and DMA sweeps (respectively) showing differences between the catalyzed and non-catalyzed polymers. Even the body of the application is filled with reaction mechanisms that really are not relevant to this issue at hand here: getting a patent with good claims.

If you are submitting this research to a journal such as Polymer Chemistry, you need that information. But all this additional information just detracts from getting a good patent: the information is never used in the claims at all or to differentiate this invention from previous, similar inventions. And worse yet, this information could be used by competitors in the future to show that the claimed invention should be narrower than originally issued since all this information goes to limit the claims. Suppose you find a catalyst that exhibits first- or-third order kinetics? That's not what was taught here, so the results are arguably patentable. Or a catalyst that left the DSC and DMA results unchanged? That sure seems patentable.

A patent written by industrial researchers might include kinetic information (this is a application for a catalyst after all) but it would be very crude. Mixture A cured in X hours while Mixture B cured in Y hours. No modeling, no theory, no kinetic parameters. It would only include DSC and DMA information to differentiate a new invention from previous inventions. While this lack of information gives the impression that industrial researchers are being secretive (and to some extent they are), they are also being defensive and trying to get and keep the broadest claims possible for their invention. Academic researchers would do well to learn from this approach.

The less you can say in a patent application, the better.

Hat tip to Geert Bleys of the Innovations in Polyurethanes blog for noticing this patent application.

Previous Years

September 15, 2014 - Plastics Scorecard v1.0 - I can't wait for v2.0

September 15, 2011 - Follow Up on Yesterday's Post

September 15, 2010 - Purging

September 15, 2010 - A Strange Connection (if it even exists)

September 15, 2009 - Tires for the moon (and beyond)

Monday, September 14, 2015

Plastic Chairs

Plastics chairs are a part of modern society, but they are not always greatly appreciated. However many design artists latch onto the the great choices in materials and shapes - and to some extent, the low costs - to try and create something significant. Yesterday the Style Page at CNN.com reviewed 13 classic designs for plastic chairs in a slide show. Amazingly, the slides mention not only the materials that were used in making the chair, but also the manufacturing technique. The pictures of each chair are primitive as you can see with this one of the Panton Chair, my personal favorite:

The author clearly states their love of plastic, but of course has to throw in the standard, poorly-thought-out obligatory environmental complaint about the material as well:
"At the same time, plastics have created a contaminated, toxic world that needs to be reconsidered and resolved. There is great hope in biodegradable plastics, 100% recycled plastics, deriving plastics from sugar cane, plant-based and other renewable sources..."
A biodegradable chair? Wooden chairs are already biodegradable, but I am completely unaware of any facility will take them and compost them. You can burn wooden chairs, but you can burn plastic chairs as well. And as I discussed in the past, plant-based plastics will largely be identical to the petroleum-based plastics that we have today. Huge investments are being made to make bio-based ethylene, propylene, etc that will protect the huge investments already made to polymerize and process these plastics. Novel monomers (and thereby novel polymers) are possible, but it can take a decade and more to get a new polymer to be profitable, meaning that you need plenty of money and the guts to keep spending it when you don't see a payoff anytime soon.

While people love novel designs, no company is going through the expense of developing a new material just so that designers can be creative with it. I hate to be the one to disappoint the designers, but the future feedstocks for plastics chairs will look pretty much like what we already have today.

Previous Years

September 14, 2012 - The PR for Medical Research is Overhyped??? You Don't Say

September 14, 2011 - Here's What Single-Use Plastic Really Does

September 14, 2010 - Human Skin

September 14, 2010 - Plastics are loved by "The New Yorker"

September 14, 2009 - It's an attack on Organikers, I tell you

September 14, 2007 - Science Tattoos

Tuesday, September 08, 2015

3-D Printed Plastics to Detect Milk Spoilage

The website Plastemart.com is reporting on a new 3D-printed plastic cap with embedded electronics that can detect the freshness of milk. Well, since it's 3-D printed, it's gotta be good, right? (Just like 30 years ago, anything that was done on a supercomputer had to be right. Gee, when was the last time you even heard the word "supercomputer"?)

You can read the article and see that it is some clever chemistry and engineering, but with no/none/zilch/nada-chance that this will ever make it to a grocery store near you. Of ALL the items in a grocery store, milk takes the cake for being the most price sensitive. Ground beef is a close second, but most stores end up selling milk for no profit, or even for a loss, just to get people to come into the store. So now these researchers are asking the store to take a bigger hit by paying for this fancy lid?

Furthermore, unlike other foods such as ground beef contaminated with e. coli or cold cuts rife with listeria monocytogenes, spoiled milk will not kill you. It probably won't even make you sick. The smell of spoiled milk should be enough to knock you out, but even if your nose is plugged and you missed the horrific odors, the taste and consistency will certainly have you spitting it out well before you could ever consume a large enough quantity to endanger you. Seriously, have you ever heard of someone dying from spoiled milk?

But there is one place where this technology could be useful: at the dairy farms themselves. Mastitis and other dairy diseases can greatly impact the quality of raw milk and when mixed with larger volumes of milk from healthy cattle, can lead to serious loses. The dairy industry is always in the need of faster and more robust tests and this might fit the bill. But consumers? Forget about it.

Previous Years

September 8, 2011 - Deuterated Gels

September 8, 2010 - Raising the Tg of PLA

September 8, 2010 - Interviewed by Chemjobber

Thursday, September 03, 2015

One Half Dozen

I don't guarantee that my count is accurate, but of all my contemporaries when I was in grad school, a total of 6 of us have gone on to be professors. Besides myself, there is
  • W. Burghardt (Northwestern)
  • M. E. Mackey (Delaware)
  • A. Tree (Oklahoma State)
  • B. Khomami (Tennessee)
  • B. Edwards (Tennessee)
That's a pretty impressive number considering that the research group was only about 10 people. It's even more surprising given the general atmosphere of the department. This was chemical engineering, not chemistry, and the overall attitudes towards teaching vs. working in industry are entirely different than what I perceive it to be in chemistry. It is perfectly acceptable in a chemical engineering department to have no desire to teach or do a post doc (assuming that you could even find one, as they are rather rare). To express a desire to work in industry puts you in the majority of students and that career option is never considered a failure.

But despite all of this, there are now 6 (or more (?)) of us working as professors.

Wednesday, August 26, 2015

Circular Plagiarism

So blog posts have been few and far between as I prepare for teaching. Classes begin in a week and the expected panic is beginning to set in.

Last night there was the orientation for new faculty. Over dinner, a couple of adjuncts spoke about the Adjunct Council, a newly formed group that advocates on the behalf of and provides support for adjuncts. During the informal Q and A session, the topic of plagiarism came up and that there should be some statement in our syllabus addressing the matter. Someone asked if the college had a formal statement that we could use. One of the moderators replied something to the effect of "No, I just used a statement that I copied from somewhere else".

Thank goodness I didn't have any food or drink in my mouth as I just lost it, bursting out in laughter and saying in a tone just loud enough for the people at my table to hear: "That's plagiarism!". They all started laughing, breaking the rather somber mood and drawing the attention of the entire room. I then felt obligated to repeat my remark out loud so that everyone could hear it. The speaker blushed as red as an apple. I tried adding "...as long as you don't provide attribution" but I think that was lost in the noise.

Sheesh, classes haven't even started and I'm already causing trouble.

Previous Years

August 26, 2014 - The Ebola outbreak would be so much worse without plastics

August 26, 2011 - Diary of a Summer Intern

August 26, 2010 - Scanning Plastic Films for Defects

August 26, 2010 - Grammar

Friday, August 14, 2015

Plastics to Aid in Fighting the California Drought

The State of California is suffering through a 5-year drought with no end in sight. Ironically, as much as Californians love to rage against plastics (instituting endless bag bans and regulating countless other chemicals that are added to plastics or used in their production), there are more and more examples of plastics being used to help the state in this time of need.

In just the past few days, the city of Los Angeles placed 96 million black, hollow polyethylene balls in a water reservoir. The balls float on top of the water reducing evaporation, keep away birds and provide other benefits.
The Worlds Largest Ball Pit - Black HDPE Balls in the LA Water Reservoir
That would have been fun to help install. And if the reservoir ever runs dry, then LA will have the worlds largest ball pit.

At the same time two, plastic pipe manufacturers are using the drought to help sell their products. Nationwide, about 16% of all purified water is lost due to leaks and broken pipes with most of the pipes being ductile iron. Large volume plastic pipes were not available when most of these water systems were originally installed but they are available now. PVC pipe is ridiculously easy to join. As many homeowners know, you brush on the primer and adhesive and then push the two pieces together. Voila - a solvent weld that is most likely stronger than the original pipe. Doing this with a 12" OD pipe or larger is a little more difficult due to the weight of the pieces, but the heavy equipment needed to lift them is readily available. HDPE pipes are also available. HDPE cannot be solvent welded however, so more specialized equipment is needed to heat up the end sections to allow them to adhere, but again, this is being done more and more in new installations.

The unfortunate part of this is that California is 5 years into the drought and only now are these steps being taken. Neither step will eliminate the drought, but they will allow existing water supplies to last longer. Had these steps been taken 4 years ago, the Hollywood movies stars might still be able to water their lawns. It's just another reminder of our inability to focus on long-term problems until they reach a crisis state.

Previous Years

August 14, 2014 - Oh Brave New World!

August 14, 2013 - The Pitch Drop Experiment for the Impatient

August 14, 2012 - Polymerizing Antioxidants

Thursday, August 13, 2015

I'm Going Back to School

Summer is winding down here in the Northern Hemisphere and that means that it's back to school time. For the first time in 26 years I will be part of that. There will be the usual excitement of meeting new students/professors /staff, finding my way around a campus that I am unfamiliar with, new books and supplies and making sure I am in the right classroom at the right time.

That last item is easily the most important, as if I'm not in the right room at the right time, there will be no class. This year, I'm returning to the classroom not to sit in one of the seats, but to stand at the front and speak - I'm taking at position as an adjunct professor at Augsburg College.

You may not have heard of this school, but you should have. Peter Agre, winner of the 2003 Nobel Prize in Chemistry received his B.A. in Chemistry there. Knowing that, I'm going to be constantly wondering if I am looking at a future Nobelist as well.

As you can imagine, the next few weeks will be pretty busy getting ready to this new adventure, so posts may not be as numerous or as lengthy, but they will continue. And once the school year starts, I'm sure that I will have plenty more material to blog about. I can't imagine that the students won't be an endless font of new ideas and items to discuss.

Previous Years

August 13, 2014 - A No-Brainer Approach to Turning Biowaste in Thermoplastics

August 13, 2013 - Limits to Innovation in F1 Racing

August 13, 2012 - A New Perspective on the Great Garbage Patch

August 13, 2010 - More Aspen Research Video Available

August 13, 2009 - More fun from the New England Journal of Medicine

August 13, 2008 - My only political comment and it's not political at all

Thursday, August 06, 2015

PVC-induced Acroosteolysis?

I look forward to my inbox on Thursdays because in it will be the links to The New England Journal of Medicine's "Images in Clinical Medicine". These are open access images that doctors from around the world have submitted that show something that is visually unusual in a patient that they examined and possibly treated. The images can be photographs, MRI's, x-rays, etc. and have a brief discussion about the condition, treatment and outcome.

This week, PVC was considered (but ruled out) as inducing the fingertip bones in this man's hands to be absorbed by his body:

The condition is called acroosteolysis [1]. PVC gets blamed for lots of things, but I thought it was odd that it, the polymer itself, would get the blame. A more likely cause would be the monomer (vinyl chloride, VCM), the catalyst or any of the various additives that are added to PVC (and there are A LOT of additives added to PVC). I dug a little further and that is where it gets interesting. I found a link to an Italian-language report on acroosteolysis in people that used to manually clean the tanks used to polymerize PVC.

"The disease was observed for the first time in mid-1963 in Belgium (Jemeppe) in a chemical plant operated by Solvay, and affected two workers whose job was the manual cleaning of vessels used for the polymerization of vinyl chloride; similar cases occurred in almost all PVC production plants all over the world, but not in the plants where the main activity was the production of vinyl chloride monomer (VCM). Little more than one hundred cases are described in the scientific literature, and this number increases by a few dozen if we consider known but unpublished cases. These figures confirm the rarity of the disease, which peaked at the end of the 1960's and disappeared during the 1970's, probably due to the complete elimination of manual reactor cleaning. Observation of the disease lasted no more than fifteen years and the disease was not replicated in experimental conditions on animals.

The disease was clinically characterized, had a short latency (from several months to several years), was rare and unequivocally linked to the manual cleaning of PVC polymerization tanks. However many questions still remain open: the period when the disease first appeared (many years after the start of PVC production in the world), the etiology of the disease (the most accredited hypothesis considers three concomitant factors: a chemical factor--one of the many substances used during polymerization, and particularly vinyl chloride monomer, a physical factor--microtraumas of the fingers during manual cleaning, individual susceptibility), the pathogenetic mechanism (in particular: the role of skin, respiratory, or digestive system, as entrance door), a method (or test) to screen subjects potentially predisposed to the disease. In our view acroosteolysis of manual tank cleaners in PVC production is an occupational disease which is distinct from "vinyl chloride disease" as identified by Viola (1974)."

That's a puzzler alright. PVC was first produced commercially back in the 1920's and yet this condition didn't appear until the 60's. So what changed? And what is there that the workers would have been exposed to that would have led to acroosteolysis, such a very rare and unusual condition? Despite what the doctors stated, I doubt that it is the PVC itself as workers that process PVC in all it forms don't seem to suffer this way. Most of the additives to the PVC would be added in a post-polymerization operation (having all those compounds around during the polymerization would be a nightmare). So what was the cause?

Given that the condition amongst workers has extinguished itself, I doubt that we will ever know what the cause was.

[1] If I am parsing this word correctly, acro- refers to the extremity, osteo- refers to bone and -lysis refers to the breaking down. Acroosteolysis - a good name.

[2] That second to last sentence needs some help, but it's beyond me as to how to rewrite it correctly, so I left it as it was originally written.

Previous Years

August 6, 2014 - So you want to develop sustainable polymers, do you?

August 6, 2013 - Where There's Smoke, There's Bad Smells

August 6, 2012 - The Secrets of Oobleck Revealed - Partially

August 6, 2010 - Backlash on BPA - Infertility Report

Friday, July 31, 2015

Maybe this is why the Philae Probe didn't "Stick the Landing"

The Philae lander that made (multiple) contacts with the 67/P comet last November has finally reported back some data on the chemistry at the surface. And it appears that there is a polymer, polyoxlmethylene (POM) amongst the mix. The official report is behind a firewall (which means I haven't read it), but there is also extensive reporting by Carmen Drahl (formerly of C & E News) and C & E News itself.

Whenever I think of POM, two thing immediately come to mind. The first is that this polymer probably has more names associated with it than any other polymer. POM is also commonly referred to as acetal, polyacetal, and Delrin (the latter being a tradename that is well on its way to becoming generic). Most other polymers have only a couple of names associated with them.

But the other immediate thought is POM is well known for it's low coefficient of friction (COF) - it's excellent for making plastic gears and other parts that slide past each other. So is the low COF part of the reason that the probe had such a difficulty in landing and staying landed?

Don't laugh. There may be lots of polymer on the surface

"If the polymer covers much of the comet, it could explain the object’s dark colour..." For such a strong visual effect, the polymer is would have to be more than just a monolayer. Additionally, "The polymer may also be masking signals from other interesting compounds formed earlier in the comet's history...", again, indicative of a thicker layer. (And did you notice how junky polymers are already taking the blame polluting up the comet.)

Landing a probe on any comet will always be challenging since the gravitational attraction is so low. But having a slippery surface is only going to make matters worse. This is still mostly speculative, but if it turns out in the future that there actually is a slippery, thick layer of POM on the surface, well, you read it hear first.

Previous Years

July 31, 2014 - Polyprefixicide

July 31, 2012 - Accelerated Aging, Flash Photography and Museums

July 31, 2009 - "It's all about the Entanglements"

Thursday, July 30, 2015


One of the more fascinating puzzles in contemporary polymer science is polydopamine. As you might guess, this is made from polymerizing dopamine, a fairly simple molecule:
Even though this monomer has been polymerized and extensively studied for 8 years, there still is disagreement on what the structure of the polymer is. And this has nothing to due with whether the polymerization proceeds through the 3- or 4- hydroxy group. The hydroxy groups are not part of the polymer's backbone (as far as anyone can tell!).

Look at this rogues gallery of structures that have been proposed:
Possible structures of polydopamine
Source ($) and Source (OA)

All from such a simple monomer. Heaven forbid someone would want to copolymerize something in along with it.

While polymer science is fairly advanced and the number of good mysteries is being reduced, I'm glad something like this can come along once in a while to keep us on our toes.

Previous Years

July 30, 2009 - Class Action Junk

July 30, 2008 - Getting Violent over Glass

Tuesday, July 28, 2015

Real World UV Degradation of PET

Long-time readers of this blog are well aware of my ongoing complaints (1, 2, 3, 4, 5, 6, 7, 8, 9 and 10) about researchers running poorly designed UV exposure tests on polymers. So when PlasticsNews yesterday highlighted a new report from Plastic Technologies, Inc., on how UV exposure leads to yellowing in recycled polyethylene terephthalate (PET), I figured it would make for some terrific blogging fodder for tomorrow.

I was wrong. Or at least my expectations were wrong. Here's what changed my mind completely:
"Two-liter PET bottles produced using a commercial grade of PET were used for this study. This resin did not contain any ultraviolet absorbing additives. These virgin bottles were crushed, stacked five to six deep, and placed in uncovered open sided crates to afford maximum exposure to the elements. These crates of bottles were then placed on the roof of Plastic Technologies, Inc. building in early January. Every three months, the bottles in the crates were agitated so that those on the bottom had a chance over time to move to the top or outside edges. Another set of bottles was stored indoors approximately 18-inches under a fluorescent light source. This light source was left on continuously, exposing the bottles for two months. A third set of bottles was stored and protected from light exposure for one year for use as a control."
I can't believe it. Sure, they ran the mandatory expose-it-to-a-continuous-UV-light-source-to-scorch-it-beyond-all-reason, but they also had material exposed to REAL WORLD CONDITIONS. Industrial researchers got right what so many academic researchers have gotten wrong!

The results of the testing were pretty interesting as well. While the sunlight did yellow the PET a little, putting the exposed PET through an extruder (once again, duplicating REAL WORLD CONDITIONS) drastically increase the amount of yellow. While the authors did not offer an explanation, I would guess that the sunlight initiated a degradation reaction (perhaps along the lines of a Photo-Fries reaction) and the additional thermal cycle really allowed for the reaction to run wild.

But this graph on the right is especially telling. The y-axis is the "b*" values from a Hunter L*a*b* spectrophotometer. I won't go into all the details, but positive b* values are a measure of yellowness. The plot is for test plaques, meaning the PET has already gone through the extruder. The blue diamond is the yellowness for the samples exposed to a fluorescent lamp for 2 continuous months. That point is well off the curve, and shows that sunlight is more more aggressive about degrading PET. This also re-emphasizes my point to ALWAYS run real world exposure controls. Accelerated aging is not just a matter of counting photons - it is far more complicated. Woe unto those who think otherwise.

My hats off to Dr. Schloss and Ms. Brown for getting the research right. You can simulate real world conditions all you want, but nothing beats using the real world conditions. Is it really that difficult of a concept?

Previous Years

July 28, 2014 - The Failed Dow Chemical/Kuwaiti JV: Is it finally over?

Monday, July 27, 2015

A Sweet Ring-Opening Polymerization Scheme

Before I get to today's polymers, let me ask you a few questions:
  • If you could see a movie for free or pay to get a review of the movie, which would you choose?
  • If you could eat a restaurant for free, or pay to get a review of the restaurant, which would you choose?
  • If you could go to a concert for free or pay to get a review of the concert, which would you choose?
Hold your answers until later when the motivation for them will become clearer.

There was a polymer chemistry paper published last month in the Journal of the American Chemical Society (JACS) that brings two separate ideas together to produce some novel polymers.
  1. Ring opening polymerizations proceed best when the ring is small in size and has some strain built in to help the reaction along. Epoxies, being a three-member ring are a great example of this, capable of reacting at room temperature or below. (Many epoxies are shipped on dry ice). But smaller rings offer only a small choice in what will end up in the back bone. Larger rings offer more options, but greatly reduced reactivity.
  2. A recently developed ring-opening methathesis polymerization (ROMP) is called relay polymerization and is illustrated here:
    Relay polymerization
    In the enyne starting material, the triple bond moves to the left to form the five-member ring found in the product and at the same time opens the six-member ring up for polymerization.

The authors combine both of these concepts to produce polymerizations such as this:
Trigger polymerization
While ROMP polymerizations are well known, they have always had restricted chemistries until now:
"For the first time, polymers with arbitrary functionality (ester, amide, sulfonamide, aliphatic, aromatic, heterocyclic, etc.) within the backbone can be produced while still providing control over molecular weight and molecular weight distribution."
Having esters in the backbone means that this material could be hydrolytically degraded. While such degradation is most often undesirable, at other times, it can be a blessing. Regardless, just having it as an option is helpful.

And this polymerization is extra sweet as the trigger is built using saccharin as a starting material. All in all, very clever.

I need to mention that the article is open access. Anyone can read it for free. But if you try and read a review of it at Nature Chemistry, you have to pay. So, one last question:
If you could read a research article for free or pay for a review of it, which would you choose?
(Shameless self-promotion: my article reviews have always been and always will be free.)

Previous Years

July 27, 2012 - The Most Overlooked Analytic Technique in Polymers - DSC

July 27, 2011 - Bad Management or Excellent Engineering?

July 27, 2010 - Gelators - Part I