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Eight molecules that changed the rules of the game: Bakelite

Date: 2010-08-25 13:00
Author: Stefano
category:Chemistry
tags:bakelite, molecules, plastic
slug:eight-molecules-that-changed-the-rules-of-the-game-bakelite

Rule changed: it started the world of plastic we live in

|Bakelite|

When it comes to materials for making tools, housing, chariots, and dishes, humanity had only one choice for many thousands of years: use what nature provided. Clay, rocks, metals, resins, rubber, and wood were the most common materials directly available for harvesting. As primitive technology improved, materials with new and interesting properties were created, such as glass and concrete, but at that time there was little or no understanding of the "magic" behind the process, the new material's properties, or how to improve them, except by trial and error. The discovery process improved considerably when the rules of physics and chemistry were rationalized: the gained understanding of existing natural materials made possible to design similar ones, either partially or completely synthetic, endowed with unusual interesting properties. One remarkable example of these man-made compounds is plastic: discovered at the end of the 19th century, plastic materials changed and still change the world.

|image1|

Plastics are defined for their properties of being easy to shape, extrude and cast; they belong to a much larger class of chemical compounds called polymers, long molecules assembled from small, simple, repeated components called monomers. The polymer class also includes famous compounds such as DNA, RNA, proteins, Wood (mainly composed by Lignin and Cellulose), and natural rubber (a polymer of isoprene).

Rubber is an interesting compound. It has positive qualities such as strong resistance, flexibility and elasticity, but it also has drawbacks, like being very sensitive to temperature: too hot, and it becomes sticky; too cold, and it becomes fragile. With the recently acquired chemical knowledge about matter and transformations, chemists in the 19th century tried to modify natural rubber to improve its characteristics. Vulcanization (cooking rubber with sulfur) was independently discovered by Friedrich Ludersdorf and Nathaniel Hayward in 1834 as a method to improve its mechanical properties. Some years later, first Thomas Hancock then Charles Goodyear improved the process, giving a strong impulse to production of tires for the growing car industry.

|Shellac flakes|

Another interesting, all-natural material was Shellac, a resin produced by an Indian bug, Laccifer lacca, as a material for its cocoon. Known since antiquity, it was clearly very expensive both for production and logistics, but had a lot of nice properties, including the possibility of being molded and shaped with additives, such as pulverized wood. Finding a cheap replacement for Shellac became one important objective for chemists at the end of the 19th century.

Partially man-made plastics: Parkesine, Viscose and Galalith

The first partially man-made plastic to reach commercial status was Parkesine, produced by Alexander Parkes in 1855 as a chemical modification of nitrocellulose, in itself a modification of natural cellulose with a process discovered independently by Henri Braconnot, Théophile-Jules Pelouze, Christian Friedrich Schönbein, and Rudolf Christian Böttger. Parkesine was a financial disaster, due to its poor physical properties: fragile and prone to warp. In addition, industrial production was very expensive. It took John Wesley Hyatt to define a better process (discovered by accident) and commercialize the product as celluloid in 1870.

Celluloid is thermoplastic: it can be heated, molded into a shape, then cooled down to create the desired object, and this process can be eventually repeated. It replaced ivory, turtle shell and bone, in particular for the production of billiard balls, and it was also used as a film support for the growing movie industry.

[caption id="" align="alignright" width="240"]`|Nitrocellulose| <http://en.wikipedia.org/wiki/File:Nitrocellulose_hexanitrate.jpg>`_ Nitrocellulose, starting product for celluloid[/caption]

Unfortunately, celluloid is highly flammable: from exploding billiard balls to film catching fire during storage, transportation and projection, handling celluloid always carried a potential fire hazard. Accidents reaping many lives occurred. Celluloid is still used today to produce ping pong balls.

Through a different modification of cellulose, Louis Marie Hilaire Bernigaut de Chardonnet invented Viscose in 1891 to replace silk with an artificial fiber. The usual problem of flammability was later solved (after actual accidents happened) by Charles Topham. Further refinements to the process and formula by Cross, Bevan and Beadle led to the commercial fiber known as Rayon. The same substance was later used by Jacques Brandenberger to produce Cellophane.

Galalith was another partially man-made plastic. It used a milk protein, casein, combined with formaldehyde. It has good properties, but it was mainly used for buttons and jewelry, and in the long run it wasn't competitive in price and production against crude oil-based plastics.

The first completely man-made plastic: Bakelite

[caption id="" align="alignright" width="150"]`|A radio made of Bakelite| <http://en.wikipedia.org/wiki/File:Bakelite_radio.jpg>`_ A radio made of Bakelite[/caption]

The year is 1907. Leo Hendrik Baekeland, a native Belgian emigrated to the United States, synthesizes and then presents to the world the first polymeric compound produced from monomers, and not from modification of pre-existing natural compounds. This polymer, which he names Bakelite, is the first completely man-made polymer, and is going to become a life changer whose legacy is everywhere around us.

Baekeland was a very proficient inventor. He moved to USA to continue his studies and practice in chemistry. Among his first inventions was a new, faster photographic paper whose rights were immediately bought by Eastman Kodak. The large amount of money for the rights and the production facility made Baekeland rich, and allowed him to push chemical research forward. He wanted to explore in more details the polymer world, to find a substitute for shellac.

[caption id="" align="alignleft" width="50"]`|Phenol| <http://en.wikipedia.org/wiki/File:Phenol_chemical_structure.png>`_ Phenol[/caption]

Bakelite is obtained combining phenol (a derivative of benzene obtained from coal tar) and formaldehyde (obtained from wood alcohol). These two compounds react and create a highly ramified network, a phenol-formaldehyde resin. To be fair, Nobel prize winner Adolf von Baeyer got the material already in 1872, more than 30 years earlier, but he did not get the chance to refine the process, nor to make it a commercial product. Baeyer's student Werner Kleeberg and many others were even closer, but either they were focusing on something else, or they didn't find the "sweet spot" to produce a valuable product.

[caption id="" align="alignright" width="70"]`|Formaldehyde| <http://en.wikipedia.org/wiki/File:Formaldehyde-2D.svg>`_ Formaldehyde[/caption]

In fact, most of Baekeland research went into finding the right temperature and pressure for the polymer to form with the proper characteristics, stay in resin (liquid) form for as long as required, and then poured into shapes so that it could harden. This is a vivid example of comparison between pure research and industrial R&D.

Bakelite was totally revolutionary for the time: it can be mold into any shape; it is an excellent electric insulator and had a considerable heat-resistance; once solidified, it does not melt again; it is not flammable, a killer feature compared to Cellulose; it accepts filler material such as wood flour, for better properties and reduced cost; it is light and resistant, an essential additional property for production of weapons.

Initial uses of Bakelite were electrical insulation for industrial connectors, but the real kick to Bakelite use came when the patent expired in 1927: competitors took grip of the expired patent, prices collapsed and new varieties and colors of Bakelite arose under the new brand name of Catalin, among many others. Catalin had better quality and a wider range of colors, making it ideal for the consumer-level market. The Swedish company Ericcson made telephones with Bakelite in 1931. Jewels made of Bakelite were created and endorsed as new fashion objects. It replaced the very expensive ivory for poker chips and billiard balls. It dropped production costs, allowing radios and many common house tools to become more common. The list of products made of Bakelite/Catalin is almost endless.

New plastic materials are synthesized

Following Bakelite, the chemical industry discovered and produced a myriad of new plastic materials, or found innovative uses for previously known compounds. Commercial and technical brands quickly entered the layperson vocabulary: Lucite, Plexiglas, Rayon, Cellophane, Nylon, Neoprene, Styrene-Butadiene Rubber (SBR), PVC, Teflon, Polyethylene, Polycarbonate, PET. If you look around you, chances are that you will find one or more of these compounds, either for a bottle, for kitchenware, in some parts of your car, or in your clothes. In some cases, the strange and intriguing properties of a plastic material made it nothing but a toy, but an incredibly successful one: Silly Putty.

Today, plastic is the most used material in the world, and research focus shifted to other important requirements. We discovered that some plastics can be used to produce electricity, conduct electricity, accumulate electricity, convert electricity into light, transport light, purify water from organic sludge or from poisonous metallic ions.

[caption id="" align="aligncenter" width="500"]`|Flexible display| <http://en.wikipedia.org/wiki/File:Ecran_oled_flexible.jpg>`_ A flexible display made of organic LED (OLED) on polymers[/caption]

We realized that in general, plastic is not easily degraded by the environment, and it remains unscathed for a long time. This produces very unpleasant situations for our planet's ecosystem, and consequently to us: the Great Pacific Garbage Patch is an accumulation of mainly plastic pollutants, converged in central Pacific by the oceanic gyre, as beautifully and sadly depicted in this short movie.

Some plastics have been designed to be quickly degraded by environmental bacteria, although to be fair it can introduce a whole new sets of problems. The most responsible strategy is to recycle as much as possible.

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