Plastic Polymers
Plastics are polymers - long-chain carbon-based or
"organic" molecules. These chains are made up of
repeating fundamental molecular elements, or "monomers."
The term plastics covers a range of mostly synthetic or
semi-synthetic organic condensation or polymerization
products that can be molded or extruded into objects or
films or filaments. The name is derived from the
fact the properties are in a semi-liquid state that is
malleable, or has the property of plasticity.
Plastics vary immensely in temperature tolerance,
hardness, resiliency. Combined with this
adaptability, the general uniformity of composition and
lightness of plastics ensures their use in almost all
industrial applications today.
Natural Polymers
People have been using artificial organic polymers for
centuries in the form of waxes and shellacs. A plant
polymer named "cellulose" provides the structural strength
for natural fibers and ropes, and by the early 19th
century natural rubber, tapped from rubber trees, was in
widespread use.
Eventually, inventors learned to improve the properties of
natural polymers. Natural rubber was sensitive to
temperature, becoming sticky and smelly in hot weather and
brittle in cold weather. In 1834, two inventors,
Friedrich Ludersdorf of Germany and Nathaniel Hayward of
the US, independently discovered that adding sulfur to raw
rubber helped prevent the material from becoming sticky.
In 1839, the American inventor Charles Goodyear was
experimenting with the sulfur treatment of natural rubber
when, according to legend, he dropped a piece of
sulfur-treated rubber on a stove. The rubber seemed
to have improved properties, and Goodyear followed up with
further experiments, and developed a process known as
"vulcanization" that involved cooking the rubber with
sulfur. Compared to untreated natural rubber,
Goodyear's vulcanized rubber was stronger, more resistant
to abrasion, more elastic, much less sensitive to
temperature, impermeable to gases, and highly resistant to
chemicals and electric current.
Vulcanization remains an important industrial process for
the manufacture of rubber in both natural and artificial
forms. Natural rubber is composed of an organic
polymer named "isoprene." Vulcanization creates
sulfur bonds that link separate isoprene polymers
together, improving the material's structural integrity
and its other properties.
Some interesting polymers sites:
Plastics,
Yahoo
Plastic
Polymers | Celluloid &
Rayon | Bakelite |
Polystyrene & PVC |
Nylon
Synthetic
Rubber | A
Plastics Explosion |
Plastic Recycling |
Packaging Products
