Polyester Trivia

Every textile expert’s first test when working in a laboratory is to differentiate polyester from nylon. Although the manufacturing process for each yarn is totally different, it is difficult to distinguish polyester from a nylon fabric. When shopping, without looking at the label, we may intuitively tell the two fabrics apart based on experience: Synthetic yarn in pants or a blouse is usually polyester, in socks or luggage, usually nylon. Although the difference in look and feel may not be obvious, there are differences in properties that will influence synthetic yarn selection in product design.

For example, nylon has higher abrasion resistance than polyester. For high friction products such as luggage, back packs, upholstery, nylon is preferred. Window curtains are made of polyester because of their superior UV resistance. Insulation layers in winter garments will be made with polyester non woven fibers because they absorb much less water than nylon which better maintains the insulation factor. The higher heat resistance of polyester made it ideal for garment longevity as laundering, drying and ironing have less detrimental effects on polyester than on nylon. Nylon has a melting point of 220°C and polyester 260°C (although nylon 6,6, an industrial grade of nylon, also melts at 260 °C). Incidentally, the most popular method to differentiate polyester from nylon is to expose the yarn to the flame. The polyester leaves a dark bead, whereas the nylon melts quickly away. The official method is to soak the fiber in formic acid, if it dissolves at 100 °C after 3 minutes, it is nylon. Polyester melts in methyl salicyclate.

Polyester was invented by John Rex Whinfield and James Tennant Dickson, employees of the Calico Printer's Association of Manchester, who patented "polyethylene terephthalate" in 1941. The first polyester fiber was called Terylene iwhich was first manufactured by Imperial Chemical Industries or ICI in 1941. But everyone recognizes better the second fiber named Dacron; it was commercialized by Dupont.

By the way, the polymer that became polyester was a derivative from Wallace Carothers’s work who was in 1929 in charge of Dupont’s research division. However, DuPont chose to concentrate on the more promising nylon research. Polyester from ICI ended up to be nylon’s biggest competitor.

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