Thursday, April 30, 2015

Living Hinges

One mechanical entity that is almost exclusively limited to being constructed from polymers is a "living hinge". Trying to describe a living hinge can be difficult, so let me provide a few pictures of living hinges you might have around the house:
Living Hinge - Ketchup bottle
What American home doesn't have a ketchup bottle or two?

Fish sauce bottle

The common feature in all cases is that there is a thin strip of the polymer that provides a flexible, continuous (usually) hinge between two other more substantial parts. Trying to make such a hinge from metal would be pretty challenging (let alone ceramics or other rigid materials).

Living hinges are most commonly produced from polypropylene (PP) and polypropylene copolymers, not only because that material is plenty cheap, but also because when properly made, the hinges can last for years. I have a large polypropylene tub that originally was used for dog food some 12 years ago. It has since been repurposed for storing bird seed in an icy-cold/sultry-hot Minnesota garage. It has been flexed two or three times a week for its entire life, and other than where mice tried chewing through it last winter looking for some free seeds, it still works beautifully.

Last week when helping out with the laundry, I ran into a living hinge that I thought was a little unusual. It's a container for Tide Pods:
Living Hinge - Tide Pods
Tide Pods Container

I say it is unusual because the container is polyester. While polyester (PET) is used for living hinges, it's usually for food packaging such as this:
Living Hinge - Fresh Herb Container
Fresh Mint
or other items at the grocery store. PET is much more expensive that PP, but it is used in food packaging because its clarity shows off the food so well. But that argument doesn't hold up with the PET used for the Tide Pods as it is not clear at all. Additionally, the hinge will be flexed quite a bit - the container holds 72 pods so that is at least 72 cycles of opening and shutting. So why does P & G use PET instead of PP? I have no idea. Perhaps some other aspect of the molding (cycle time for instance) dominates and allows for the use of a more expensive resin.

The term "living" hinge has always bothered me as there is nothing alive about the hinge. It's a hinge. A thin plastic hinge. But misuse of the word "living" in polymer science and engineering is nothing new. Look at "living" polymerizations. In a living polymerization, the polymerization reaction runs until the monomer is depleted, but unlike with more common reactions, the termination reaction never kicks in to permanently halt the polymerization. If more monomer is added to a depleted living polymerization, the reaction can pick up right where it left off, even if the newly added monomer is different that what was used previously. But is the living polymerization still "alive" while it is in that paused, deplete state, or is it more like a dormant state? (Or maybe even a "zombie" state as was discussed yesterday?) I guess polymer scientists and engineers have a hard time distinguishing between "live" and "dead". But then again, I have wondered that about my colleagues themselves at times too, so perhaps the misuse is understandable.

Previous Years

April 30, 2014 - Dow Chemical Keeps Plodding Along and Silencing Critics

April 30, 2012 - Another Set of Rants about a Rejected SBIR Grant

April 30, 2010 - Natureworks

April 30, 2010 - This Changes Everything!

April 30, 2009 - Skip the ER for potential heart attacks and find a spectroscopist instead

April 30, 2009 - This isn't even peer-reviewed

Tuesday, April 28, 2015

The Antibacterial Properties of Silver can be "Long Lived"

While polymeric materials are seldom consumed by bacteria, the surfaces can still provide a location for bacteria to live on, especially if the surface is contaminated with substances that can sustain bacterial life. One common way to prevent this is to add various toxic metals to the polymers such as silver or copper. The use of these metals to control bacteria has been known for centuries, but a new research report (OPEN ACCESS!) puts a new twist on just how effective silver can be: the bacteria that have been killed by silver nitrate are themselves capable of killing additional bacteria. Apparently the silver in the dead bacteria serves as a reservoir to kill additional bacteria. The researchers believe that copper would be able to act in a similar fashion.

The researchers provide an "interesting" take on what they observed: Dead animals are able to kill living animals of their same species. There is one and only one word for this type of behavior: ZOMBIES! And that's exactly the word that the researchers used. It's a little bit of a stretch as the dead bacteria are not actively pursuing the live ones, but it certainly draws your attention in.

Previous Years

April 28, 2010 - Overqualified?

April 28, 2010 - The Cox-Merz Rule Rules

April 28, 2009 - More Science Funding

Monday, April 27, 2015

Using Drones to Find Ocean Plastic?

Hardly a day goes by without someone suggesting a new use for drones. But using them to study ocean plastic? I doubt that that will work well at all.

Glancing at the article, you would think otherwise, especially with a picture like:
Ocean Plastic - NOT!
leading off the article. If the plastic pieces were actually that visible, drones would be helpful.

But the reality of ocean plastic is quite different. A researcher from the Scripps Research Institute recently took a picture from the middle of the eastern Garbage Patch. This is what she saw:
The Middle of the Eastern Ocean Gyre - Where's all the plastic?
Quite a different perspective, isn't it.

This is not a denial of the Garbage Patches and Ocean Plastic. The plastic is there alright. But you have to look closer and concentrate to see it since it looks like this:
What ocean plastic really looks like
It's mostly small particles and not very closely clustered together. Which is most unfortunate, as that dilution prevents the plastic from being recovered.

Unless these new drones have super powerful magnification and a smooth ocean surface, they aren't going to useful at seeing much of any except the big stuff. Certain groups of people are okay with finding just the big stuff, because that can then be used to paint the evocative images of "Garbage Patches" and "Floating Islands" "the size of Texas". But that is not the least bit representative of reality.

Previous Years

April 27, 2011 - Closing the Loop in Biotechnology

April 27, 2010 - Adhesives vs. Rivots

April 27, 2010 - Strange Math

Tuesday, April 21, 2015

Using a Reusable Bag isn't so good for the Waistline

The issues surrounding the use of reusable bags at the grocery store just got a little more complicated. That's because Harvard and Duke researchers found out that using a reusable bag changes your behavior, and not all for the good. People toting around a reusable bag did buy more organic foods, but they also felt good enough about themselves and their helping-the-environment that rewarded themselves with junk food:
"It was clear that shoppers who brought their own bags were more likely to replace nonorganic versions of goods like milk with organic versions. So one green action led to another. But those same people were also more likely to buy foods like ice cream, chips, candy bars, and cookies. They weren’t replacing other items with junk food, as they did with organic food. They were just adding it to their carts."
Maybe we need to update the old saying "A moment on the lips, a lifetime on the hips" to "Don't bring your own bag or your butt will start to drag"?

Hattip to Don Loepp at PlasticsNews for this item.

Previous Years

April 21, 2014 - The Week That Was(n't)

April 21, 2011 - Small is not Necessarily Better (with Plastics)

April 21, 2010 - Visible Light Photocatalysis - Even in the Dark

April 21, 2009 - The Double-Edged Sword of UV Light

Wednesday, April 15, 2015

So just how many polymer chemists are there?

While polymers have touched just about all aspects of our lives, you might be tempted to think that most chemists work with them. While it is true that all working chemists do to some degree, i.e., they wear plastic safety glasses and rubber gloves, I want to probe the subject just a little more deeply and ask: what percentage of chemists work in the development and/or manufacturing of polymers?

This is surprisingly difficult to answer. My own personal perspective sans data is that very few do. If social media is representative at all of chemists, then the fact that there are very few bloggers and tweeters on polymers compared to the number of chemists involved in those media supports my position. Also compare the size of their readership and/or followers. Further, look at how few polymer research articles are published in general chemistry journals such as JACS or Angewandte Chemie. Or how few polymer talks are given at the ACS national convention.

As I've said in the past,
"If you want to feel like an outcast chemist, take up polymer chemistry."
Googling for an answer doesn't help much. Typing in the question outright doesn't provide any answer, so I took a different approach and searched on "X% of chemists work with polymers", and went with X from 10 to 110. (Yes, 110% since we all know that polymer chemists always give 110%. More on that in a minute.) The only hits I got were at 50% and 70% from the ACS and the University of Oregon respectively. Those numbers are preposterous. No citations are provided (not surprisingly).

I finally hit some real paydirt when I looked at the federal government's tabulations. The Bureau of Labor Statistic (BLS) has collected all the relevant data and provides an accurate picture (open up the spreadsheet for chemists if you to see all the details). In 2012, there were just under 88,000 chemists. Of that number, 2100 worked in "Resin, synthetic rubber, and artificial synthetic fibers and filaments manufacturing", 1900 worked in "Paint, coating, and adhesive manufacturing", and 600 in "Plastics and rubber products manufacturing". That's 4600 in manufacturing. There are some broader categories that undoubtedly include polymer chemists, such as the nearly 18,000 that work in "Scientific research and development services", and the 4600 that work in "Educational services; state, local, and private". Even if everyone of these last two groups were all polymer chemists, that would still only total to 27,200 chemists, not even 31% of the total workforce. I think a more realistic number would be just 10% of those last two groups, which would be 2260 more for a grand total of 6860 chemist. This is not quite 8% of the workforce.

Keep in mind that this is just "chemists". Chemical engineers, materials scientists etc. are not part of the numbers. It could be argued that the ACS pages includes a disclaimer:"As many as 50% of all chemists will work in polymer science in some capacity during their career."(emphasis added), but I'm not buying that either. Jumping fields and going into polymer chemistry is no more likely than an organiker becoming an analytical chemist or a computational chemist become a bench inorganic chemist. It can be done, but that is the exception, not the rule.

Also, it needs no mention that these are numbers for the US only but I would expect similar percentages for other countries. If some international readers have different numbers (or even anecdotes), please feel free to provide feedback either in the comments below or via email (address is on the upper left side of this page).

One final closing thought: If a mere 8% of chemists are able to provide the incredible bounty of polymers that the US and much of the world enjoys, I can't help but think that we are the James Brown of chemists - the hardest working people in chemistry!
James Brown - Papa's Got a Brand New Plastic Bag

Previous Years

April 15, 2013 - A Novel Flame Retardant Coating for PU Foams

April 15, 2011 - Show me a picture, please!

April 15, 2010 - More Olefin Polymer Oxidation

April 15, 2009 - Self-Healing Polymers

Tuesday, April 14, 2015

Will recent articles countering the Food Babe do any good?

Taking a whack at the "The Food Babe" has been very popular the last few weeks. There is one by the ScienceBabe, another one by Science Based Medicine and a third by Violent Metaphors. There are plenty more as well. (Heck, I even a satirized her myself a few weeks ago.) While I applaud the efforts of those people to spend a lot of time in providing factual rebuttals to the Food Babe's errors, I really question whether it will do any good at all.

It all comes down to the concept of "presumption". I can't speak for other countries, but here in the US, presumption is most often associated with the criminal justice system, where defendants have a presumption of innocence. While this presumption has lots of implications that are carried along with it, I want to focus on just one element today: with the presumption of innocence, in a case that is "tied" evenly, i.e., one where the arguments on both sides are equal, the defendant wins. The tie goes to the defendant in the same way that in baseball, the tie goes to the runner.

But this is all associated with the criminal justice system. In the court of public opinion, the opposite is true. The tie goes to the accuser. This is not true for every individual in the public, as many are thoughtful and rational and will make their own decision, but for the public as a whole, presumption is with the accuser. If it is a "he said/she said" argument, the accuser will get the benefit of the doubt.

It shouldn't be this way, but it is. If you doubt me, think about the presumption of innocence: the mob mentality that sides with the accuser is why we need the presumption of innocence codified in the first place. It's the reason Mark Twain said, "A lie can travel half way around the world while the truth is putting on its shoes."

And while our fellow scientists are putting together effective replies to all of the accusations of the Food Babe, very seldom do they do more than just counter the accusations, leaving them merely negated. Meaning that what the public sees is a "He said/ she said" argument, albeit carried on with scientific terms. The Food Babe speaks up first, and while the arguments from the scientists are true and accurate, they merely cancel out the original arguments, leaving the public with a "tie" to decide. And who do they decide with? Who has presumption? Who wins the tie?

To take down the Food Babe, you must do more than just deconstruct her arguments; you need something extra to put you over the top and there has to be an accusation or two (or more) in it. And that needs to be presented from the get-go, not as an afterthought. Continuing to do otherwise is to keep "preaching to the choir". Thanks, we already got the message and scientists all over are snickering at the Food Babe.

If you want to win in the court of public opinion, you need to understand the rules and the rules are very different than the rules of scientific arguments. So while scientists everywhere think of themselves as smarter than the Food Babe for making some of the stupidest statements about science imaginable, she still goes on and on. So who's the smart one?

Previous Years

April 14, 2014 - Ketchup Rheology Video

April 14, 2011 - What's In a Name? Marketing Gobbledygook

April 14, 2011 - On the Move

April 14, 2010 - Modulation

Thursday, April 09, 2015

Material Choices and Testing Protocols for Condoms

Last week Slate magazine published an in-depth article entitled "We Should Have a Better Condom by Now. Here’s Why We Don’t." Before clicking on the link, I would suggest proceeding with caution, as there numerous photographs of condoms placed on many different types of produce. In other words, it may be a little bit unsafe for work. Or around children. Or your parents. But I would recommend reading it if you are interested. It provides a serious look at the many sides of something that has far too much politics involved (as you will soon see.)

My comments here will be just limited to comments. No photos or images. Not ribald jokes. Just a serious discussion about some of the issues about the mechanical testing and the polymers being explored for new condoms. At times like this, it's appropriate to pull out the middle French expression - Honi_soit_qui_mal_y_pense (May he be shamed who thinks badly of it).


When Carl Djerassi, the inventor of "the Pill", recently passed away, there was much recognition of the role that the pill has played in the lives of women around the world. While it has numerous "off-label" uses, it's most commonly used for birth control. As important as that is, a lowly piece of rubber, a condom, has to do all that and more. Not only are condoms used for birth control, but also for preventing the spread of sexually transmitted infections. And yet as important as this product is, the article points out that very few innovations have been or are being developed, despite the well-known shortcomings in existing products.

The reasons for the lack of developments are numerous. Part of it is lack of appropriate testing procedures. The testing procedures that the US Food and Drug Administration (FDA) uses are designed to mimic vaginal sex and no other sex act.
" 'It’s a little political, because I don’t think the sponsors—i.e., condom manufacturers— necessarily want their name identified in publications that they’ve done this big anal research study...The FDA would love the information, and I also think the NIH [National Institute of Health] would love the information, but they also don’t want to be known as funding the anal intercourse study.' Take a moment to imagine how Republicans in Congress might react if the NIH used taxpayer dollars to study the mechanics of anal sex."
But this does raise a legitimate question - What are the mechanical demands placed on a condom? Once they are known, then it is much easier to develop a test that can measure the material performance of interest. But current testing is well removed from reality.
"To test condom strength, the air burst test, in which randomly selected condoms are filled with air to determine the volume and pressure at which they burst, won out over the tensile strength test, which stretched condoms mechanically to determine the force required to rip them."
Air burst? Tensile testing (i.e., pulling the condom from both ends and measuring the force)? How could either of these be under consideration at all? Wouldn't some type of friction test or other shearing stress better mimic reality?

The article also discusses the materials being used and developed. The vast majority of current condoms are made from latex (natural) rubber. Some polyurethane condoms have been developed, but the author gets a raspberry from me for not knowing that there are countless numbers of polyurethane rubbers that all have different mechanical properties. As such, polyurethane condoms should not all be grouped together as one. But she quickly makes up for it when it comes to a condom that the manufacturer describes as being made from "a revolutionary material - polyisoprene". The author gets plenty of kudos from me for pointing out what many readers will already know - the macromolecule that makes up the rubber in latex rubber is polyisoprene. This "revolutionary" material is simply the synthetic equivalent of latex rubber and has been around for decades.

The discussion of materials naturally leads into a discussion of "feel", which is a large drawback for current condoms. For reasons that are well removed from condom design, I've always thought that latex would have about as good of feel as you could hope for. After all, they are the preferred choice of surgeons for whom "feel" is critical in surgical procedures. Surgeons who develop sensitivity to latex are always complaining about how the latex-free gloves have less feel to them. I would have expected the same of condoms. The article also mentioned the high cost associated with clinical evaluations that prevent smaller companies from innovating with new materials - maybe a tie-in with surgical gloves would help expand the potential market and the interest of investors.

The overall tone of the article is not optimistic. Between the snickering and political stands, it's hard to get support for the work. Having better condoms would increase their usage. It's much like PPE is for chemists - the more comfortable it is and the easier it is to use, the more likely it is to be used. If you've still had a great fitting pair of safety glasses on when you get home from work (like I have), you know what I mean.

As always, comments are welcomed below. And as always, you can comment anonymously.

Hattip to Chemjobber for bringing this article to my attention.

Previous Years

April 9, 2014 - Those Rich Petroleum Engineers

April 9, 2013 - Can We All Get Along?

April 9, 2012 - Poor Posed Concerns About Chemical Safety

April 9, 2010 - A Neat New Set of Solvents

Monday, April 06, 2015

The Dirty Little Secret of Agricultural Plastics

You may have seen this story entitled either as "The Biggest Source of Plastic Trash You've Never Heard Of" or "How can agriculture solve its $5.87 billion plastic problem?". It came out late last week and is making the rounds different sites. The article provides a high level overview of how plastic films are extensively used in agriculture for a number of reasons such as water retention and warming the soil so as to extend growing seasons. People have recognized the waste and potential for is use for years (since at least 2003), so it isn't quite as new of a concern as the headlines may have you believe. Much of this plastic is never recycled, but the article really downplays why.

It's the dirt.
"Another big issue in recycling agricultural plastics is dirt and debris."
Another big issue? How about it being the biggest issue. I was at a plastics recycling conference a few years ago and all the speakers kept talking about was the dirt. Dirt is going to contaminate the plastic and discolor it (unless it is already black). Consumers are all in favor of companies using recycled plastics and some are even willing to pay a little more for it, but no one is willing to give up on appearance. White plastic with dark brown specks, line and swirls? Not too likely.

At that conference, one of the speakers showed prototypes how using the unwashed plastic could generate tiles for use in plastic sidewalks. The appearance was nice, as the nonuniform discoloration provided visual interest, much like slate, marble, granite and other natural materials do. I've not heard much about that application since, but it was mentioned in passing in this article. Sadly, there aren't too many applications like that that can take in the plastic "as is" and run with it. The plastic can be washed, but then you have to dry it afterwards. Water and molten plastics just don't get along.

Previous Years

April 6, 2012 - Chemophobia - from a grant reviewer?

April 6, 2011 - Plastics to the Rescue in Japan

April 6, 2010 - Wind Power Problems

Wednesday, April 01, 2015

My "Interview" with "The Polymer Babe" stirs up some serious legal trouble for me

Yet again, the Polymer Babe
Polymer Babe: Why Are You Making Such Trouble for Me?
What a difference a day makes. I woke up this morning look forward to a beautiful Minnesota Spring day with sunshine and the feeling that snow, frost and cold temperatures are pretty much behind us.

And then I looked at my overnight emails.

Holy cow. Legal trouble. Big legal trouble. A potential lawsuit. Is this really happening?

Take a good look at the "Polymer Babe" interview that I had up last week, as it will NOT be there much longer. Or maybe take a few screenshots. Or whatever. I really don't care. It just doesn't matter. Why? Well, ponder over the email I received just a few minutes ago:

April 1, 2015

Dear Dr. Spevacek,

My law firm represents the Society of the Polymer Industry (SPI). If you are represented by legal counsel, please direct this letter to your attorney immediately and have your attorney notify us of such representation.


As legal counsel for the the SPI, we are quite taken aback by the many false claims in your recent post on your "It's the Rheothing" blog, "An Interview With the Polymer Babe".

For you to suggest or otherwise endorse the concept that polyvinyl alcohol contains alcohol, or even worse yet, can induce inebriation goes beyond the pale of scientific evidence. As a scientist and practicing chemist, you clearly understand that the the word "alcohol" refers to hydroxyl functional groups and that very few alcohols will upon human consumption lead to any state of stupor.

Similarly, to suggest that other polymers are similar to table salt and that water-based polymers should not have water within their contents is to defame polymeric materials. The SPI has spent countless decades in service to the polymer industry and your mocking tone and poor attempt at humor is not welcomed.

If you do not comply with this cease and desist demand within the next 10 days, the Society of the Polymer Industry will pursue all available legal remedies including seeking monetary damages, injunctive relief, and order that you pay court costs and attorney's fees. Your liability and exposure under such legal action could be considerable.


Ima Loiyer, B.A., M.S., Ph. D., J.D., LL.D., Esq.
Of Counsel,
Dewey, Cheatem & Howe
1060 West Addison Street
Chicago, IL 60613

Being unemployed (still), I can't fight something like this, so I'll have to comply. Looks like few people can take a joke anymore. It's sad. Literally.

Update: Yes, this was an April Fool's joke. There are plenty of tip-offs. First, the date at the top of the letter. A much more subtle one is the industry group name. SPI is the Society of the Plastics Industry, not the Polymer industry. The attorney's name - "Ima Loiyer"? - read it out loud if you need to. The law firm of "Dewey, Cheatem and Howe" goes back decades and even has its own Wikipedia page. And 1060 West Addison Street is Wrigley Field, made famous in the Blues Brothers movie.

Until next year!

Previous Years

April 1, 2014 - A Big Announcement

April 1, 2013 - An Open Letter to Justin Bieber

April 1, 2012 - the Trump Journal of Science

April 1, 2011 - Polly Mer Announces Presidential Run

April 1, 2010 - BPA - The Shocking Truth Revealed!!!

April 1, 2009 - Stimulus Bill Backfires - Bans All Plastics