Wednesday, June 27, 2012

The Most Important Reaction for Polymer Chemists that is NOT a Polymerization Reaction

Today's post is about the most important chemical reaction for polymers that is NOT a polymerization reaction. The reaction is the moisture-cure silanization of glass and other silica surfaces, a pre-treatment that is given to fiberglass [1] so that it will interact favorably with the polymers used in making fiberglass composites.

Any time I've needed to increase adhesion to glass, I've been successful in incorporating similar type silanes into the coating formulation, an approach that often will work well enough to justify skipping the extra time and processing of a pre-treatment so I've never actually used this reaction as a pre-treatment. At the same time however, if you've ever looked through the trade literature of the major silicone suppliers, you can't help but to have not had it drilled through your head.

As a result, there is little point in me repeating that well-established mechanism execpt for one little detail: a 2011 research article [2] suggests that the standard mechanism for the cure as actually incorrect.

The classic mechanism for the cure is
while the new proposed mechanism is
The researchers looked at differences in the FTIR spectra (specifically the asymmetric methylene stretch at ~2923 cm-1) when a trimethoxysilane and a triisopropoxysilane were coated repeatedly on a glass surface. With the trimethoxy compound, the spectra showed that additional coating layers resulted in additional coverage, where as with the latter silane - a far bulkier compound with three isopropoxy groups - additional coats did not increase coverage. This result is not possible with the classic mechanism which suggests that the distance between the added central silicon atoms will be the same regardless of the size of the alkoxy groups. The proposed mechanism however, can account for the bulkiness of the alkoxy groups and how they can prevent the reaction of additional coating layers with the substrate.

I find it interesting that the proposed mechanism results in three Si-O-substrate bridges from a single silane molecule.

I would be most curious to see how this mechanism plays out with a slightly different set of silanes - dipodal silanes. These a molecules that have two groups of trialkoxy silanes on the same molecule - hence the name (dipodal = "two feet"). Dipodal silanes are available with different spacers between the silanes, as well as different alkoxy groups. With these additional variables, it should be possible to further test the proposed mechanism.

[1] Just a note on symantics: fiberglass is the generic term while Fiberglas (with a capital F, and just 1 s) is the trademarked name for Owens-Corning's version of this.

[2] Free access until 12/31/2012, although you may have to register with the RSC.

Tuesday, June 26, 2012

Ted Turner: Ban All Plastics

There are outlandish statements and then there are outlandish statements. Ted Turner, aka "The Mouth of the South" (not from the South, of the South) was in the latter category this last week when he spoke before the Rio+20 conference and noted that
"Plastics...are at the top of his priority list to save the world. “I think what we should do about plastics is ban them”"

Psst. Hey Ted. If you ban plastics, then all the electrical wires won't have any insulation and that means nobody will be able to safely plug their TV's into the wall to watch CNN or use their computers to read the CNN website or any other website to read about all the great ideas you have. You might want to rethink a ban on plastics, o.k.?

Monday, June 25, 2012

Researchers who found Estrogenic Activity in Nearly All Plastics Being Sued for False Claims

A little over a year ago, I commented on the lousy experimental conditions and conclusions in a report that claimed that nearly all plastics had estrogenic activity (EA) associated with them, just as bisphenol-A (BPA) does. While the authors of the report (employees of the companies PlasticPure and CertiChem) had some back-and-forth with me across the internet about these issues, the matter has now become much more serious for them as Eastman Chemical has filed suit against the company for claiming that Eastman's Tritan plastics show estrogenic activity by relying on a screening test (called the MCF-7 test), "which is known in the scientific community to be a non-definitive, non-final test for making determinations of EA and from results of other unreliable testing protocols".

I was much more specific in my criticism of their research (inappropriate UV light conditions - something I will always call out - as well as other inappropriate testing conditions such as using an autoclave to simulate a dishwasher - why not just use a dishwasher and avoid all the problems with a simulation?) and suggested that their test procedures possibly ended up creating the EA materials that would otherwise not be there.

I will be curious as to how the lawsuit proceeds. Any guesses on which side my Schadenfreude money is?

Friday, June 22, 2012

Towels in America

Stuart Cantrill, the Chief Editor of Nature Chemistry has commented via Twitter on more than one occasion that when he leaves his home in England and travels to the US, he is annoyed that the TV screens are bigger than the towels. Since I had the joy last week of taking an old-fashioned road trip out west, I decided to research the matter for myself. Here's some of what I found:
At the Days Inn in Silverthorne Colorado,the towel is clearly larger than the TV. Score: towels 1, TV 0.

I found a similar towel/TV ratio at the Holiday Inn Express on SR 595 in Las Vegas:
Rats! It looks like "What Happens in Vegas Stays in Vegas" is more than just an expression. Well, you'll just have to take my word on it. Towels 2, TV 0.

In fact, the only spot that I found where the TV was larger than the towel was at one of the gas stations in Irvine:
for a final score of towels 2, TV 1. I certainly hope that Nature Chemistry is has a big enough travel budget that that aren't forcing their people to overnight in 24-hour gas stations! .

Clearly more research is needed. If I put in for a grant now, the funds should show up this winter so that I can research the towel/TV ratio along the Gulf of Mexico.

Thursday, June 21, 2012


I was reminded recently of the role that donuts play in industry and how it differs from their role in academia. In the latter, donuts are most commonly used as an enticement to get grad students to show up for the seminar of a guest speaker. But in industrial settings, donuts are offered up to the line operators or anyone else that is working their behinds off in order to get your new-to-the-world, way-more-difficult-to-process-than-the-normal-polymer to process properly. If they're out their twittling knobs on their machine to make you look good, you better make sure they are not hungry.
Think twittling knobs is easy? The actual twittling is, and since you've got all that education that you picked up at the university, you can make all kinds of theoretical predictions about what the settings should be and what will happen when you lower the temperature or increase the screw speed and you can run that machine yourself without the operator. But you know what? He knows all the subtle little nuances of his machine that you don't, and you want to take advantage of that. All you've done is read the manual. Donuts are always a great option to get this cooperation, and don't you even think about submitting them on your expense report either. That's really bad Karma!

Wednesday, June 20, 2012

A Vinyl Window with a Great R-Value

Plastics News is reporting on a new window with an R-14 insulation value. As you would expect, the window is of vinyl construction (Plastics News isn't going to report on an all-wood window now are they?). An R-14 rating for a window is pretty high while most other windows are in the 1-3 range. This is still quite short of the R-value for insulated walls which are in the 20 range.

The problem with just looking at the R-values however, is that they influence the overall insulative properties of a wall in a non-linear fashion. For example, let's look at a R-2 window that takes 10 % of an wall that is otherwise R-20. The R-value for the wall is NOT R = A1R1 + A2R2 = (0.9 x 20) + (0.1 x 2) = 18.2, where the A's are the relative areas of the wall/window and the R's are the R-values. Instead, the correct way to calculate the overall R-value is to consider the overall resistance that arises from parallel resistances – just like we all learned in elementary circuits. Heat escaping through the wall is taking a path parallel to that escaping through the window. This means that 1/R = A1/R1 + A2/R2 = 0.9/20 +0.1/2 = 0.045 + 0.05 = 0.095, so that R = 1/0.095 = 10.5. An R-value of 10.5 for a wall is nowhere near the 18.2 calculated earlier. You can also see in this case that the even though the area of the window is just 10% of the wall, the heat loss though it is the same as through the wall, and a window that is just 10% of the wall is pretty small. If the wall is 8 ft x 10 ft, then the window would be only about 10 in x 12 in, something like the window on an airplane.

If we now substitute the R-2 window with an R-14 window, the R-value of the wall rises to 19. Alternatively, we can increase the size of the window to 30% of the wall (30 in x 36in) and still have an R-value of 17.7. That's why an R-14 window is exciting news.

Tuesday, June 19, 2012

You Know Those SPI Recycling Symbols? They Show That The Plastic Is Recyclable, Not Biodegradable

Last week while eating dinner in a restaurant [1], I overheard someone at the next table explaining to her dining companions the meaning of SPI recycling symbols, such as this one:
The topic came up as this table of elderly diners were packing up their unfinished portions in plastic containers provided by the restaurant. At first, the conversation was about the microwavability of the containers, but then it went on to the SPI symbols which were visible on the top of their plastic boxes. One women clearly stated (and was not challenged by the three other people at her table) that the symbols meant that the containers were biodegradable. The three arrows in a circle were used to show that the container "would return to the earth", and then without taking a break, she then looked at her husband and said "just like what's going to happen to you soon".

As you can imagine, I was quite surprised that someone would think this (about the symbols, not her husband). While it is understandable that someone could create this illusion by themselves if the symbols were only recently introduced, the symbols have been around for decades, well before biodegradability become the rage that it currently is [2]. How a 20-year old recycling code could morph in someones mind into a biodegradable code is beyond me.

I decided that discretion was the better part of valor and did not try to correct her. Embarrassing her in front of her husband and friends would not have helped our cause, and beyond that, I seriously doubted it would have done much good anyway.

[1] It was a wonderful seafood dinner on the restaurant's dock overlooking the water in Newport Beach, California. Jealous yet?

[2] I am well aware of earlier efforts (and the resulting blowback) from circa 1990 to create "biodegradable" plastics, such as when cornstarch was added to polyethylene to create "biodegrable polyethylene" garbage bags. But it has only been in the last few years when polylactic acid hit the big time that the general public has really had to think about the difference between recycling and biodegradation.

Tuesday, June 12, 2012

Guar Gum Shortage

Halliburton, the worlds' largest supplier of hydraulic fracturing services (aka fracking) is reporting reduced profit margins this quarter because of a shortage of a natural-based viscosity modifier - guar gum. In other words, the best way to get frack gas out of the ground, some of which will be used to make synthetic polymers, is to use a natural polymer. Isn't this ironic?

The shortage of guar gum is rather different than the shortage of nylon-12 that's been discussed earlier. With natural products such as guar gum, you are going to be facing the usual ups and downs of market prices, but there will not be any sudden events equivalent to an explosion that will take out 30% of the guar bean crop in an instant. What's happening here is that people are starting to frack gas at an unecpectedly fast rate and the guar bean supply wasn't increased at the same rate. This shortage can be eliminated by planting more of the beans, although the time for a crop to be planted and harvested is not that much less than it is to repair a destroyed manufacturing site, so in some ways, it is equivalent to having a production plant blow up.

Monday, June 11, 2012

Sandwiches, Gluttons and Picky Eaters

I have another guest-blog post over at The Chemistry Blog that briefly looks at the role that metallocenes play in olefin polymerization. Have a look, please.

Thursday, June 07, 2012

100,000 Visits

Sometime in the middle of the night while sleeping, the Sitemeter counter at the bottom of the page hit a milestone - 100,000 visits - since it was installed. (Go ahead, click on the meter and you can see what I see about the visitors to this blog.)

What is the big headscratcher for me however, is the search terms used to find this blog:
"skilled and educational people and their contribution towards country"
This visitor from India looked at 2 pages for a total of 11 seconds and decided that I don't fit that description. (Most people reach that decision in less time than that.) It doesn't help that the page he first visited is the one where I (mockingly) note all the contributions of the late Kim Jong-Il to polymer science.

Thanks to all 100,000 who have visited here - I appreciate everyone of you.

Wednesday, June 06, 2012

What's Wrong With This Video?

This video on plastics and sustainability is maddening. Particularly since it was produced by one of my almae matres, the University of Minnesota, who should know better.

At 1:10, "Some plastics contain chemicals that can harm people and other living things" Only some plastics contain chemicals? Not all plastics?

At 1:24+, "[Unrecycled plastic] gathers in landfills, on roadsides and in oceans filling nature with trash" The irony is that any plastic trash generated at the University of Minnesota (as well as the entire Twin Cities area) is not landfilled, but is instead burned to generate electricity. (More on this in a bit.)

At 1:44+, "Imagine if we green chemistry to design safer plastics, replacing harmful chemicals with natural compounds found in grasses, fruit and grains." That's right: natural chemicals = good, synthetic chemicals = bad. Chemophobia is alive and well at the U of M! And now we know what to do with all that extra food that we have lying around.

At 1:53+, "Imagine if we produced plastics with less water, less energy and fewer greenhouse gas emissions" Wouldn't growing feedstocks use more water than drilling for oil/gas does?

At 2:03, "Or if we made plastics that could be composted, recycled or used for energy" You mean current plastics can't be recycled? Or that they can't be used to for energy? This shows again that whoever made this tape doesn't even know what happens to their own garbage.

There are also numerous emotional pleas throughout the video that I'll just leave alone. The factual errors themselves are enough to embarrass me as an alumni of an institution that should never had let this tape out.

Tuesday, June 05, 2012

A New Industry Group to Fight Plastic Phobia

Ho hum, yet another article on plastic phobia and the response of the plastics industry to it. The headline reads "New Group Aims to Clear Plastics' Name", and the article lists some of the usual causes for the public to dislike plastic so much:
"“Some unlawful businesses have damaged the reputation of the plastics industry in their profiteering. Combined with the lack of effective regulatory efforts, it has resulted in a trust crisis among consumers,” Yang said. In addition, because consumers generally lack deep knowledge of plastics and are bombarded with misleading, anti-plastics media reports, plastics has been demonized."
The only reason I mention this article however, is that this new plastics industry group is not here in the US or even in Europe, but in China. I wish this new Chinese plastics group the best of luck in their efforts. If the irrational fear of plastics driving this is the same as it is here and in Europe, they will need all the luck they can get.

Monday, June 04, 2012

PPE for the Fashionable Industrial Polymer Chemist

June 4th is Personal Protection Equipment (PPE) Day.

Nate: Kate and I are here today to discuss the latest fashion do's and don't for today's fashionable industrial polymer chemist. Kate, here's a recent picture of John; what do you see here, you fashion maven?

Kate: Being an industrial chemist, John often gets to work on the big equipment in the production area, so here we see him not only wearing safety glasses, but a hard hat as well. I do think that yellow is so passe for a color, Tangerine Tango is the Pantone Color of the Year for 2012 and would make a much better choice.

Nate: Kate, you are so right, but snaps for John for adorning his helmet with the color scheme from his blog. And Kate, what I really love, and I do mean love about helmets, is that after a long day sweating over a hot twin screw extruder, you have the most adorable hat hair. If you were to see John driving home, you would think that he was a hipster that had just removed his knit hat, and we all know what a great fashion statement that is. Way to go John!

Kate, what else to you see?

Kate: Down below, John has on this pair of pair of safety shoes, as again, he is working around lots of heavy equipment. Now Nate, don't get me wrong as I know the importance of PPE, but honestly Nate, those shoes never were in fashion and if they ever do come in fashion, why I'd...I'd...I'd... well, I'd rather wear 6-inch platform shoes with fishnet stockings and a short skirt downtown after closing time than look at those shoes again.

Nate: Oh Kate, I so agree with you. Safety shoes come in so many good looking fashions nowadays that I have I pair for every outfit in my closet, and not one of them looks as awful as that pair. John dear, do yourself a favor and get an updated pair, and then call me so I can swoon over them.

Kate, does John have any other PPE to talk about?

Kate: No Nate, that's it for today, although I should mention that when John works around the really big and noisy equipment here at Aspen Research, he loves to accessorize his outfits with hearing protection. His personal favorite is the 3M 1310 banded ear plugs, so much so that he even wears them at home at when mowing the lawn or using his chainsaw.

Nate: Hmmmm, now that's an image I won't tire of...

Kate: Oh Nate, get back to business here. Those banded ear plugs are lightweight, very comfortable and maintain an even pressure on your ears no matter how far you spread the band. Oh, and did I mention that John's wife played a major role in the development of that product?

Nate: Well isn't that nice. Kate, I think we've covered it all here. Until next time, this is Nate...

Kate: ...and this is Kate...

Nate & Kate: ...wishing you good PPE fashion sense. Goodbye!

Friday, June 01, 2012

Biodegradable Polymers will not Eliminate Pollution

There is a common misconception [1] that biodegradable plastics will eliminate plastic pollution. I just don't see that happening. While the plastic will breakdown at some point (some point being strongly influenced by the amount of UV light and/or the temperature and/or the moisture around the plastic), the fact that the breakdown is not immediate means that the pollution will still be visible.

Take a look at this picture. Imagine that all that plastic will completely biodegrade to CO2 [2]and O2 over the next X months. Does that make this scene any less unattractive right now, here and today? Does anyone really believe that human behavior has changed so much that during the coming X months no additional plastic be added to that green field? Or are people going to keep tossing bags and bottles and whatever else out into the wild, replacing whatever is degrading with new material to be degraded? Pollution is a problem that requires an immediate solution, particularly visual pollution, while biodegradability is a long-term outcome. Until that magical day arrives where a piece of plastic will be smart enough to realize that it is now waste and needs to immediately decompose [3], biodegradability will do nothing for reducing pollution. Roadside and parks and oceans will look just as polluted as they do now.

I've been careful in this post to always tie biodegradability to the idea of reducing visible pollution, and that is because I am not against biodegradability for other situations. Medical sutures and staples that biodegrade are essential for modern medicine, and there are other applications where biodegradability serves a specific engineering purpose. I am not a big fan of biodegradation of plastics in compost piles as it's the irreplaceable loss of a reusable material, but at least with composting the materials, no one is being oversold on expectations. That is not the case with biodegradable plastics as a way to eliminate pollution.

[1] Rather ironic, isn't it that I'm linking to a webpage entitled "Common Misconceptions" in order to correct the misconceptions posted there?

[2] That CO2 is a greenhouse gas is ignored too by proponents of biodegradability as a solution to pollution.

[3] Don't hold your breath waiting for that to be developed. (And I'm glad I'm not having to even attempt developing such a "smart" material.)