Monday, June 29, 2015

Resonance in Plastics and Metals

The Reddit website has a popular subreddit ELI5, short for "explain like I'm 5", where people can post question that they would to have answered, but answered to someone without the technical background and jargon that is usually used. It doesn't mean to literally explain it as if you were talking to a five-year old (five-year olds woudn't be asking most of these questions anyway), I take it as if you are talking to the general public who wants to know more.

Yesterday the question was posted as to why when an object is struck, metal objects ring louder than plastic ones. Here's my explanation, albeit it is nowhere near appropriate for ELI5:
A object rings because it has acquired energy in a way that it resonates - it vibrates at a frequency and with enough energy to generate sound waves. As long as the object has sufficient energy, it will continue to ring. It cannot ring forever as the sound waves gradually reduce the amount of energy that the object has. But generating sound waves not the only way that an object can lose energy, One of the ways that plastics differ from metals is that plastics are better able than metals to dissipate energy internally. Any plastic object will show some amount of viscosity dampening since all polymeric materials have a non-zero loss modulus curve. Metals can also have internal dissipation mechanisms, but they are far less prevalent than in plastics.
Another example of this same phenomenon is seen in springs. Both metal and plastics springs exist. Given weight considerations alone, plastic springs should be everywhere. But springs are used because they store energy and return it. The same internal dissipation mechanisms that quiet ringing plastics also result in energy loss when the spring is compressed. A pogo stick with a plastic spring would be no fun at all, and speaking from personal experience, a plastic slinky is nowhere near the fun that a metal one is.


Previous Years

June 29, 2011 - BPA Followup (2/2)

June 29, 2010 - Tapes in Space

June 29, 2010 - Pretzel Logic from the Supreme Court

Wednesday, June 24, 2015

Don Featherstone, of Pink Flamingo fame, has died

The US plastics industry lost a significant figure on Monday, Don Featherstone. You probably don't recognize the name, but his most famous product is something quite familiar to most Americans, even if it is seen as kitschy and TTFW [1] - the plastic pink flamingo.
A Flock of Pink Flamingos
PlasticsNews has a short obituary that fails to mention that Don won the 1996 Ignoble Prize in Art for his creation. [2]

Tom Herzing co-authored a book with Featherstone documenting the plastic pink flamingo and in an interview said
"...but I think you have to remember that initially, they were a sign of taste. People thought that they were actual attractive decorations for their lawns. It was only after the snobs among us decided that this was a sign of bad taste, and then we had cities ban them..."
I've never owned one, but I have faint memories from 45 or more years ago that my parents might have had one or two. (I'm sure only to pull a joke on a neighbor, sticking them in their yard under the cover of darkness.)

You do have to wonder how many plastic pink flamingos will be on his grave, both at his funeral and in the years to come.


[1]










Source

[2] 1996 was a good year for the Ignobles. The Chemistry award was given to George Goble for lighting a barbecue in 3 seconds with the help of liquid oxygen.

Previous Years


June 24, 2014 - Why are polymers more complex to recycle?

June 24, 2011 - Art - from Ocean Beach Junk

June 24, 2010 - Environmental Stress Cracking

Monday, June 22, 2015

Startups, both Real and Wannabes

Word has reached me that the division I last worked in at 3M is being shut down. The division was rather unique for 3M in that it was quite small and built from scratch. Normally "new" divisions are made from combining divisions, dividing divisions, shuffling parts of division around or any combination of these options. In all cases, there is already an infrastructure available to some extent, including existing lab equipment and lab space, administrative personnel and all the regulatory support that is needed. This division however, was built from scratch, one researcher at a time. We moved into previously abandoned lab space and had to purchase all the equipment needed to get the lab up and running.

But it all came crashing down when the executive VP overseeing the division gathered everyone together and announced the shutdown. Some of my former colleagues are being assigned to existing divisions while others are "unassigned". One of my colleagues had for some time compared it to being in startup, although having worked for a startup (arguably two), I assured him that it was quite different. This shutdown is a perfect example of a real and significant difference between a real startup and a wannabe in a large corporation. The startup that I worked for, Envoy Medical had been in operation for 7 years without any sales prior to my joining it and it was another 7 years before it sold its first product. That is 14 years of living on angel funds, venture capital and whatever other funding sources the company could get money from. If the first investors didn't want to invest any further, the company was free to look for other investors. This is in direct opposition to 3M shutting down their division. The executive VP, the sponsor of the new division, decided to pull sponsorship and there was nothing the division could do. No one would dare ask another executive VP to sponsor them due to the great risk of ending their career right on the spot.

While I feel for my former colleagues who are unassigned, my heart really goes out to the undergraduate student that was helping me out part-time. I spoke with him last we and it still isn't clear if he will keep his job. He hasn't even graduated and may already be facing his first layoff.

Previous Years

June 22, 2012 - Towels in America

June 22, 2011 - More on Drop-In Replacements

June 22, 2010 - Poor Economic Analysis

June 22, 2010 - Full Disclosure

June 22, 2009 - It's finally time for bifocals


Wednesday, June 17, 2015

Glassy Materials on Mars - And the Inevitable Connection to Potential Life There

Glassy materials have sparked controversies in the past, and I suspect that the latest news from the surface of Mars will face the same future. NASA scientists have discovered impact glass, glass materials that form during/after the impact of a large, searingly hot meteoroid. But that's not newsworthy by itself, as such glasses are well known here on Earth. What make the discovery potentially more controversial is that they are proposing that signs of life may be locked into the glass:
"During the past few years, research has shown evidence about past life has been preserved in impact glass here on Earth. A 2014 study led by scientist Peter Schultz of Brown University in Providence, Rhode Island, found organic molecules and plant matter entombed in glass formed by an impact that occurred millions of years ago in Argentina. Schultz suggested that similar processes might preserve signs of life on Mars, if they were present at the time of an impact."
Glasses containing biological material exist elsewhere too, such as the bugs trapped in amber that gave us Jurassic Park and all the endlessly bad sequels. (Why don't the dinosaurs go after the movie directors and producers that hoist these stinkbombs on us? Call it "Jurassic Park goes Hollywood".) But the sap that forms amber is soft and gooey at "normal" conditions, not the red-hot heat of an impact crater, so given the apparent rarity of life on Mars in the first place, I would expect looking for signs of life in impact glasses to be the proverbial needle-in-a-haystack effort. Count me out.

But tying the discovery to "potential life on Mars" is a Standard Operating Procedure for NASA. Look at what other discoveries, interesting in themselves strictly from a scientific viewpoint, have been tied to "potential signs of Life":Is there any discovery that NASA has definitively stated as a non-potential sign of life on Mars? So then let's stop making the connection between any discovery and life on Mars. How about a moratorium on "potential signs of life on Mars" until it's actually found? (Violators would have to face off with a velociraptor.)


Previous Years

June 17, 2014 - Where did the polymer's chemistry disappear to? Here it is!

June 17, 2013 - Dow Chemical Hit With Triple Damages for Price Fixing Case

June 17, 2011 - BPA Absorption from Receipts? I Don't Think So

June 17, 2009 - At least here the Editor loses his job

Monday, June 15, 2015

Is a Vegan Tesla even Possible?

Don Loepp of PlasticsNews raised the question last week of whether PVC is vegan or not. The issue came about regarding the all-electric Tesla cars. Apparently they don't offer a non-leather interior for vegans.
"A Bloomberg report from Tesla’s annual share meeting noted how one buyer, Mark Peters, had to go through “extreme measures” to get a Tesla sedan not only without leather seats but without any leather trim at all for his vegan wife Elizabeth Peters."
Don suggested PVC as an alternative, but unfortunately, that likely won't be a viable option either. PVC usually has some stearate salt in it as a lubricant and the most common source of stearic acid to make that salt is animal fat.

The use of stearates goes far beyond PVC. They can be an additive to polyethylene, polyproplylene and a variety of styrenic polymers, mostly as lubricants, but also as acid scavengers to help with thermal stability. This is not just a concern for vegans, but others with restricted diets. That most stearic acid is made from a variety of animals (including pigs) causes concern for those wishing to keep a Kosher diet since many food packaging films have stearates as lubricants. Kosher stearic acid is available, but I don't know of any plastics producer/compounder that uses it.

But back to the Tesla discussion, I find it quite ironic that someone buying a Tesla, presumably because they are concerned about lessening their environmental impact, would prefer non-sustainable petroleum-based plastics to be part of the car.


Previous Years

June 15, 2011 - Sustainability

June 15, 2007 - PVA - Err, is that alcohol or acetate?

Friday, June 12, 2015

Plastic Windows for the Orion Spacecraft

It's not exactly breaking news (I'm still in the mode of getting caught up, so forgive me), but NASA has is going forward with replacing glass window panes with plastic for the new Orion Spacecraft. The Orion is the new 4-person spacecraft that is anticipated to be in non-orbital space for long periods of time, as much as 270 days. Plastic is obviously lighter than glass, so every pound saved in the windows means another pound of more valuable payload can be rocketed off the earth.

The windows are triple-pane, the redundancy being driven by safety concerns. So far NASA has tested replacing just one pane with an acrylic, but since that swap was successful in initial testing, a second pane will soon be swapped out. It doesn't appear that replacing all three panes is under consideration at this point in time.

Every time I read about plastics in space though, I have to shudder thinking about what the radiation (mostly gamma) will do to the poor plastic. I've blogged in the past (1, 2 and 3) about using plastics as a radiation shield, and the surprisingly positive results, so I know that the plastic can endure, but still...

I hope all goes well with this program. It would be exciting to see people leave earth orbit again (yes, I'm old enough to remember seeing the Apollo launches and Armstrong's walk). That no one, from any country in the world, has done this in over 40 years is pretty surprising.


Previous Years

June 12, 2013 - Future(?) Retractions in the Polymer Science Literature

June 12, 2012 - Guar Gum Shortage

June 12, 2009 - Front row seat to a horse race

June 12, 2009 - Guar Gum - It's not just a thickener anymore

(What's with all the Guar gum on June 12?)