03 November 2009
The invention: Asynthetic fibrous polymer used especially in fabrics.
The people behind the invention:
Wallace H. Carothers (1896-1937), an American polymer
Hilaire de Chardonnet (1839-1924), a French polymer chemist
John R. Whinfield (1901-1966), a British polymer chemist
A Story About Threads
Human beings have worn clothing since prehistoric times. At
first, clothing consisted of animal skins sewed together. Later, people
learned to spin threads from the fibers in plant or animal materials
and to weave fabrics from the threads (for example, wool, silk,
and cotton). By the end of the nineteenth century, efforts were begun
to produce synthetic fibers for use in fabrics. These efforts were
motivated by two concerns. First, it seemed likely that natural materials
would become too scarce to meet the needs of a rapidly increasing
world population. Second, a series of natural disasters—
affecting the silk industry in particular—had demonstrated the
problems of relying solely on natural fibers for fabrics.
The first efforts to develop synthetic fabric focused on artificial
silk, because of the high cost of silk, its beauty, and the fact that silk
production had been interrupted by natural disasters more often
than the production of any other material. The first synthetic silk
was rayon, which was originally patented by a French count,
Hilaire de Chardonnet, and was later much improved by other
polymer chemists. Rayon is a semisynthetic material that is made
from wood pulp or cotton.
Because there was a need for synthetic fabrics whose manufacture
did not require natural materials, other avenues were explored. One
of these avenues led to the development of totally synthetic polyester
fibers. In the United States, the best-known of these is Dacron, which
is manufactured by E. I. Du Pont de Nemours. Easily made intthreads, Dacron is widely used in clothing. It is also used to make audiotapes
and videotapes and in automobile and boat bodies.
From Polymers to Polyester
Dacron belongs to a group of chemicals known as “synthetic
polymers.” All polymers are made of giant molecules, each of
which is composed of a large number of simpler molecules (“monomers”)
that have been linked, chemically, to form long strings. Efforts
by industrial chemists to prepare synthetic polymers developed
in the twentieth century after it was discovered that many
natural building materials and fabrics (such as rubber, wood, wool,
silk, and cotton) were polymers, and as the ways in which monomers
could be joined to make polymers became better understood.
One group of chemists who studied polymers sought to make inexpensive
synthetic fibers to replace expensive silk and wool. Their efforts
led to the development of well-known synthetic fibers such as
nylon and Dacron.
Wallace H. Carothers of Du Pont pioneered the development of
polyamide polymers, collectively called “nylon,” and was the first
researcher to attempt to make polyester. It was British polymer
chemists John R. Whinfield and J. T. Dickson of Calico Printers Association
(CPA) Limited, however, who in 1941 perfected and patented
polyester that could be used to manufacture clothing. The
first polyester fiber products were produced in 1950 in Great Britain
by London’s British Imperial Chemical Industries, which had secured
the British patent rights from CPA. This polyester, which was
made of two monomers, terphthalic acid and ethylene glycol, was
called Terylene. In 1951, Du Pont, which had acquired Terylene patent
rights for theWestern Hemisphere, began to market its own version
of this polyester, which was called Dacron. Soon, other companies
around the world were selling polyester materials of similar
Dacron and other polyesters are used in many items in the
United States. Made into fibers and woven, Dacron becomes cloth.
When pressed into thin sheets, it becomes Mylar, which is used in
videotapes and audiotapes. Dacron polyester, mixed with other materials,
is also used in many industrial items, including motor vehicle and boat bodies. Terylene and similar polyester preparations
serve the same purposes in other countries.
The production of polyester begins when monomers are mixed
in huge reactor tanks and heated, which causes them to form giant
polymer chains composed of thousands of alternating monomer
units. If T represents terphthalic acid and E represents ethylene glycol,
a small part of a necklace-like polymer can be shown in the following
way: (TETETETETE). Once each batch of polyester polymer
has the desired composition, it is processed for storage until it is
needed. In this procedure, the material, in liquid form in the hightemperature
reactor, is passed through a device that cools it and
forms solid strips. These strips are then diced, dried, and stored.
When polyester fiber is desired, the diced polyester is melted and
then forced through tiny holes in a “spinneret” device; this process
is called “extruding.” The extruded polyester cools again, while
passing through the spinneret holes, and becomes fine fibers called
“filaments.” The filaments are immediately wound into threads that
are collected in rolls. These rolls of thread are then dyed and used to
weave various fabrics. If polyester sheets or other forms of polyester
are desired, the melted, diced polyester is processed in other ways.
Polyester preparations are often mixed with cotton, glass fibers, or
other synthetic polymers to produce various products.
The development of polyester was a natural consequence of the
search for synthetic fibers that developed fromwork on rayon. Once
polyester had been developed, its great utility led to its widespread
use in industry. In addition, the profitability of the material spurred
efforts to produce better synthetic fibers for specific uses. One example
is that of stretchy polymers such as Helance, which is a form
of nylon. In addition, new chemical types of polymer fibers were developed,
including the polyurethane materials known collectively
as “spandex” (for example, Lycra and Vyrenet).
The wide variety of uses for polyester is amazing. Mixed with
cotton, it becomes wash-and-wear clothing; mixed with glass, it is
used to make boat and motor vehicle bodies; combined with other
materials, it is used to make roofing materials, conveyor belts,hoses, and tire cords. In Europe, polyester has become the main
packaging material for consumer goods, and the United States does
not lag far behind in this area.
The future is sure to hold more uses for polyester and the invention
of new polymers. These spinoffs of polyester will be essential in
the development of high technology.