Things to rememberin a digital age

[Swatopluk]

Proper plastic is made from milk and vinegar (should you happen to have a dislike of Sir Formal de Hyde).

[Griffin NoName]

Aaaaargh! DavidH, not like our day at all.

As to that proper plastic, how can so many different mixtures all be given the same name (ie plastic). I shall continue to stick to polyoxybenzylmethylenglycolanhydride .

[pieces o nine]

Not so fast, Yurpeon Geezers!  Some of us have been known to glance perceptively through the jewelry in antique shops, looking for pieces like this; however, most look more like this.   

[Griffin NoName]

Love the horse. Not sure why it's under "aging gracefully"............ do only old folk wear bakelite?

[Swatopluk]

In the past most telephones (at least the casing) were made from bakelite. In the distant era when phones had a dial plate.

[Griffin NoName]

Kept one for years. Eventually threw it out. Probably everyone did that. They sort of gaineed an iconic presence, until the overheads of clutter finished them off. Ditto had an iconic early portable* radio (plastic, but not bakelite) - it got thrown away - now there is one in the V&A 20th century room - perhaps it is even the one we had........ I also have an old steam valve radio, massive wooden affair.... I have kept this.

* my son recently told me off for throwing out my early model luggable computer

Maybe we need a thread about things we have thrown away

when phones had a dial plate.

and phone numbers started with three letters.......... much better system to just numbers

[Sibling Zono (anon1mat0)]

Bakelite was also used for printed circuit boards (and in the engineering school back home those were referred generically as 'bakelites') although nowadays are made of different plastics.

[Griffin NoName]

weren't there problems with heat?

[Swatopluk]

There is not one bakelite, it is a whole class. The stuff consists of the resin and the filler, the latter can range from sawdust to flour to finely grinded rock (in essence anything powdery can be used). The physicochemical properties vary accordingly.

[Bob in a quantum-state-of-faith]

Bakelite was also used for printed circuit boards (and in the engineering school back home those were referred generically as 'bakelites') although nowadays are made of different plastics.

Fiberglas being the most common modern material, if you need a stiff circuit board.

Mylar plastic (or one of it's derivatives) if you need a flexible one.

One of bakelite's more endearing properties, is that it would burn before it would melt (typically).  It took heat to set, too-- you started out with a powder (typically-- although some forms were paste-like, about like toothpaste in consistency).

The powder or paste was pressed into a metal, heat-resistant mold of some sort, and the whole was heated up pretty damn hot (for plastic).  Certainly hot enough to burn you good.

Then, the whole was allowed to cool and de-molded.   If the mold cavity was smooth?  You did not even need to polish the result-- at most, knock off some "flash" (bits of plastic that had oozed out from the mold's edges). 

In the case of bakelite?  These "flash" bits were as sharp as a razor-blade, if you were not careful... cut too... until it broke, obviously.

That is why that class of plastic is called 'thermosetting plastic'-- it took heat to "cure", but once cured, it stayed hard-- and you could not re-soften it by application of heat-- it would burn, if you got it hot enough, but not lose it's shape.

In contrast to the other class of plastic, which does soften when heated, and can be re-shaped endlessly.  Most of these plastics are "polys"-- that is, some form of hydrocarbon molecule is tricked into going from a short chain hydrocarbon (either a gas or a liquid) into a long-chain hydrocarbon, making it a solid.   Two of the most ubiquitous are polypropylene and polyethylene.   Each are polymerized (using some sort of catalyst which is typically extremely toxic by itself) from the hydrocarbon gas:  propylene or ethylene.  Either of these is gaseous in it's natural state, and has 4 or 6 (or so) hydrogen atoms per molecule (I forget the exact formula, sorry).

One of the more useful aspects of these two, is that at normal room temperatures, these plastics are totally inert, and will not react to even the most toxic/caustic/basic of compounds-- not even fluorine gas.   Another is that neither propylene nor ethylene gas is particularly dangerous chemicals, although both are highly flammable.

  One of the nastier aspects of these two, is that nothing reacts to them once polymerized, and they can persist in the environment for centuries-- only good old sunlight will slowly and gradually break them down into bits that are reactive....

The 3rd most ubiquitous of the re-meltable plastics would be good old polystyrene-- it's more brittle than either of the above, but can be "welded" with chemicals, and has a slightly higher melting point.   Unfortunately, it has few natural "enemies" and like it's brethren, requires lots of sunlight to break down in nature.  Another bad thing:  styrene gas is... quite toxic (as I recall).  But not as bad as vinyl chloride-- which is polymerized into .... PVC... which is... everywhere the other three are not.

In an interesting bit of historical note?  One of the very earliest non-thermosetting plastics was nylon plastic--- made by polymerizing .... something I forget what.  Okay, according to wiki?  Nylon is a polyamide, which is the same class of chemicals as what we humans are made up of:  proteins (a natural "plastic").

What makes nylon interesting to me?  Is that nature has caught up with human activity-- and there exists a species of bacteria which loves to munch on nylon plastic-- it evolved to do this, since nylon was introduced in the 30's.

Which brings  up the Big Question:

Since so much of our modern technology depends on stable plastics-- including as disease barriers-- what will happen when bacteria evolve to munch on... the remaining plastics we use so much?

Food for thought...

....!

It only took 60 years or so, for bacteria to figure out how to munch on nylon... how much longer before it starts munching on PVC or LDPE?  (high density polyethylene-- >>60% of food packaging)....? 

[Griffin NoName]

What about vintage dolls bursting into flames? Or crumbling into a pile of rubbish?

[Bob in a quantum-state-of-faith]

What about vintage dolls bursting into flames? Or crumbling into a pile of rubbish?

Celluloid.

It was one of the first plastics that came after bakelite.

It was sturdy, stable (more or less), hard without being too brittle, easy to color with embedded dyes.  Paintable, etc.   It could even be made transparent....

... imagine the possibilities.

Unfortunately?  Nobody bothered to test it's environmental limits, before it rather exploded onto the market... irony?  You betcha.

Celluloid?  It's really nitrocellulose.  Easily polymerized from nitric acid and cellulose-- yes, exactly like pure cotton.   Or wood pulp for that matter.  (I think there's other chemicals involved,  but the principle ones are these).

As it turns out?  It's only slightly less explosive than actual ... explosive.

Stories of movie houses burning to the ground, because the projector jammed, leaving one frame in front of the super-hot carbon-arc light-source.... catching the film on a really hot-hot fire-- all that lovely celluloid nicely compacted in a 20" reel right above the fire, too...

... apparently, movie houses burning to the ground was seen as common enough, that nobody traced it back to highly flammable celluloid right away ...

The story goes, that some billiard balls made of cellulose (the traditional ivory beginning to become scarce) blew up in the face of an infamous cigar-smoker during an especially important (money-wise) shot ... I've no idea if that is true or legend.

But eventually, some clever person (likely was a woman-- who are more likely to pay attention to such things, in my opinion, than men) figured out that celluloid was... kinda explosive.

And it's brief, but exciting carreer as a common household building material ended with ... literally, a bang. 

Alas, there are still some vintage movies that only exist on this unstable stuff, even today .... if I owned any?  I'd store them in a pure nitrogen atmosphere, just in case.  In a heavy bunker too...

[Swatopluk]

Celluloid billard balls had another problem when introduced into the Wild West. If two balls hit each other too hard the sound was like that of a percussion cap leading to everyone within hearing range to draw their revolvers.
----
As for PVC munching bacteria, there is a lot of research done to breed such but with little success yet. Slightly more successful are attempts to get bacteria to dehologenate liquid compounds (like carbon tetrachloride) but few can survive in the stuff and even fewer can eat it and at a very low rate.
---
On the opposite end 'liquid wood' is making inroads. Looks like ordinary plastic but is almost completly made from wood and biodegradable.

[Bob in a quantum-state-of-faith]

On the opposite end 'liquid wood' is making inroads. Looks like ordinary plastic but is almost completly made from wood and biodegradable.

Cool. 

One thing that is often forgotten?  Is that cellulose is basically a natural polymer-- a naturally occurring plastic, if you will.

And yes, there are quite a number of microscopic critters who are happy to munch away on it.   If we could figure out how to control the shape and rate of the polymerization process of cellulose?  We could replace most of our packaging with natural cellulose-- which can be 100% recycled into all sorts of useful stuff already, like newspapers or cardboard boxes.



Imagine this:  a specifically tailored algae which literally uses sunlight, water and air to grow the cellulosic packaging material-- the power requirements would be minimal here-- sunlight, and a source of moderately clean water.  It would create the cellulose from atmospheric CO2 and atmospheric Nitrogen, combined with splitting the water using the solar+chlorophyll process.    It would be truly carbon neutral, because as it was used and discarded it would break back down into... water, CO2 and Nitrogen gas...

.... what a hoot! 

You could even shred it and burn it for power-production needs-- again, the CO2 released would be what was absorbed when it was "fabricated" by the algae in the first place.

Now.

If we could only figure out how to grow it either transparent or with built-in colors...

... !

[Swatopluk]

Polyhydroxybutyric acid can already be produced by bacteria and has been used e.g. for shampoo or household cleaning agant bottles.
The problem is to get the right degree of biodegradability. The bottles should not visibly rot while still on the shelve but also not last for years on the compost heap. And it is still too expensive to produce, esp. because the PHBA can only be harvested by killing the bacteria.