Polyester

The invention: Asynthetic fibrous polymer used especially in fabrics.

The people behind the invention:

Wallace H. Carothers (1896-1937), an American polymer

chemist

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

composition.

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.

Impact

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.