We are all familiar with polyester athletic jerseys, but polyester is used to make multitude of other everyday items as well. What we commonly call polyester refers to a specific material called polyethylene terephthalate or PET. PET was first discovered in the United States but perfected and patented in Britain. Since the 1950s the public has found an increasing number of piratical uses for polyester. Even today the science of polyester production continues to evolve with new developments in the creation of recycled polyester fiber.
History
Wallace Carothers was American organic chemist, working as the lead researcher in organic chemistry at the DuPont Experimental Station in the year 1930, when he discovered that alcohols and acids could be combined to create fibers. While Carothers and the DuPont company focused largely on the production of nylon, his research was essential to the discovery of many synthetic materials, such as nylon, neoprene, and polyester. In 1941, British chemists John Rex Whinfield and James Tennant Dickson drew on Carothers' research to create and patent the first polyester fiber, which they named Terylene. Terylene, also known as Dacron, was introduced to the American public in 1951 and was known both for surpassing nylon in toughness and resilience and for not requiring any ironing.
For the next twenty years polyester production expanded rapidly to meet a demand for low-cost apparel. However, by the 1970s popular interest in polyester had dropped off due to the roughness of the material. It was not until polyester microfibers were introduced to the public in 1991 that polyester regained it's currently popularity with garment production. Since then, polyester and cotton production have expanded to account for more than 80% of all fiber production world wide.
Production
There are four basic forms of polyester depending on the intended use for the material - filament, staple, tow and fiber fill. Filament yarn is what is most commonly used to create polyester garments and products, while staple fiber is most suitable for mixing with cotton and other fibers such as rayon, nylon, wool, etc, creating those
50/50 blend shirts that are a wardrobe staple. The manufacture of polyester filament consists of 5 basic steps: polymerization, drying, spinning, drawing, and winding.
1. Polymerization
First dimethyl terephthalate and ethylene glycol come together in the presence of a catalyst to create a chemical reaction known as transesterification. The resulting chemical is combined again with terepthalic acid to create polyethylene terephalate - PET!
2. Drying
The molten PET is then dried and cut into small, hard chips.
3. Spinning
Polymer chips are melted again. The melted resin is pushed through a round metal screens called spinnerettes. After passing through the spinnerettes, the resin is cooled in the form of long strands. The solid material is now called filament.
4. Drawing
The filament is now drawn together into a single wide band called a tow. The tow is heated stretched up to five times its original length in order to align the polyester molecules into a parallel formation. This process makes the fiber both flexible and extremely durable.
5. Winding
In the final stage of the process the drawn polyester fiber is cooled, wound, and baled to be shipped out to other manufacturers who will weave the material into products such as t-shirts!
Uses
Polyester is one of the most versatile materials around, capable of being turned into thread, hoses, sails, skirts, pants, shirts, insulation and soda bottles. 60% of all PET produced internationally become synthetic fibers and are used for woven and non-woven textiles, while 30% become bottles.
Environmental Factors
With cotton and polyester comprising more than 80% of all fiber production world wide, it is important to weigh the environmental impacts of producing these materials. Producing virgin PET requires more energy then growing cotton. However, polyester garments cost far less energy to wash, dry and maintain than cotton garments. While polyester is not bio-degradable it is recyclable. For the past twenty years recycled polyester as yielded only low grade fiber, but more recently it has become possible to create high quality fiber out of recycled polyester. As the demand for recycled and eco-friendly material grows, so does the production of recycled polyester products. This means that plastic bottles, yarn, and fabric can now become tents, sails, even
custom t-shirts!
Additional Online Resources
NY Fashion Center - A brief overview of the history of polyester.
How Polyester is Made - An overview of the production process for polyester.
How Recycled Polyester is Made - A short video documentary on the manufacturing process for recycled polyester.
Industrial Chemistry - An in-depth explanation of the chemical reactions that produce PET.
Wallace Carothers Wiki - Biography on the life and work of William Carothers.
Uses of Polyester - A description of a few of the many uses of polyester.
Can Polyester Save the World? - An article on the environmental impacts of the textile industry and modern purchasing trends.
Polyester vs. Cotton - A scholarly article on the environmental impacts of cotton and polyester.
A Cotton Educational Guide - An ooShirts guide on the history and cultivation of Cotton.
