Page 39 - Carrahers_Polymer_Chemistry,_Eighth_Edition

2 Carraher’s Polymer Chemistry

of the raw rubber with nitric acid allowed the material to resist heat and not to adhere to itself. This
success attracted backers who helped form a rubber company. After some effort he obtained a con-
tract to supply the U.S. Post Office with 150 rubber mailbags. He made the bags and stored them in

a hot room while he and his family were away. When they returned they found the bags in a corner
of the room, joined together as a single mass. The nitric acid treatment was sufficient to prevent sur-

face stickiness, but the internal rubber remained tacky and susceptible to heat.
While doing experiments in 1839 at a Massachusetts rubber factory, Charles accidentally dropped
a lump of rubber mixed with sulfur on the hot stove. The rubber did not melt, but rather charred.
He had discovered vulcanization, the secret that was to make rubber a commercial success. While
he had discovered vulcanization, it would take several years of ongoing experimentation before the
process was really commercially useful. During this time he and his family were near penniless.
While he patented the process, the process was too easily copied and pirated so that he was not able

to fully profit from his invention and years of hard work. Even so, he was able to develop a number
of items.
Charles Goodyear, and his brother Nelson, transformed natural rubber, hevea rubber, from a
heat “softenable” thermoplastic to a less heat-sensitive product through the creation of cross-links
between the individual polyisoprene chain-like molecules using sulfur as the cross-linking agent.
Thermoplastics are two-dimensional molecules that may be softened by heat. Thermosets are mate-
rials that are three-dimensional networks that cannot be reshaped by heating. Rather than melting,
thermosets degrade. As the amount of sulfur was increased, the rubber became harder, becoming a
hard rubber-like (ebonite) material.
The spring of 1851 found the construction of a remarkable building on the lawns of London’s
Hyde Park. The building was designed by a maker of greenhouses so it was not unexpected that it
had a “greenhouse-look.” This Crystal Palace was to house almost 14,000 exhibitors from all over
the world. It was the chance for exhibitors to show their wares. Charles Goodyear, then 50 years
old, used this opportunity to show off his over two decades worth of rubber-related products. He
decorated his Vulcanite Court with rubber walls, roof, furniture, buttons, toys, carpet, combs, and
so on. Above it hung a giant six-foot rubber raft and assorted balloons. The European public was
introduced to the world of new man-made materials.
Within a little more than a decade Charles Goodyear was dead. Within a year of his death, the
American Civil War broke out. The Union military used about $27 million worth of rubber products
by 1865, helping launch the American rubber industry.
In 1862, Queen Victoria, while in mourning for her recently departed husband Albert, opened the
world’s fair in London. One of the exhibitors was Alexander Parks. He was displeased with the lim-
ited colors available for rubber products—generally dull and dark. In his workshop in Birmingham,
England, he was working with nitrocellulose, a material made from the treatment of cotton and
nitric and sulfuric acids. Nitrocellulose solutions were made by dissolving the nitrocellulose in
organic liquids such as ethanol and ether. Thin films and coatings were made by simply pouring the

nitrocellulose solutions onto the desired item or surface and allowing the solvent to evaporate. He
wanted to make solid objects from nitrocellulose. After years of work he developed a material he
called Parkesine, from which he made buttons, combs, and in fact many of the items that were made
of rubber—the difference being that his materials were brightly colored, clear, or made to shine
like mother of pearl. At the London world’s fair he advertised “PATENT PARKESINE of various
colors: hard elastic, transparent, opaque, and waterproof.” Even with his work he had not developed
a material that could be “worked” or was stable, and even with his hype, the material never caught
on except within exhibition halls.
About this time, John Wesley Hyatt, a printer from Albany, New York, was seeking a $10,000
prize for anyone who could come up with a material that was a substitute for ivory billiard balls,
and had developed a material that was stable and could be “worked” from shellac and wood pulp.
He turned to nitrocellulose, discovering that shredded nitrocellulose could be mixed with camphor,
heated under pressure, to produce a tough white mass that retained its shape. This material, dubbed

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