Polyester’s positive attributes for clothing lie mostly in the consumer use phase of its lifecycle, which accounts for 50-80% of a polyester garment’s total ecological footprint. Polyester garments are generally washed in cold water and drip-dried, thereby minimizing water and energy use associated with garment care.[4]
In comparison to other synthetic fibres, there is currently more research and innovation when it comes to sustainability and improving polyester’s environmental impact.
==Manufacturing ==
PET is made from ethylene glycol and terephthalic acid. From that polymer, fibers are made by a [[melt-spinning]] process, mostly in a continuous line with both the polymerization and melt spinning. The high speed at the [[spinning]] process requires the use of lubricants (spinning oils). They are commonly made of mineral oil with the addition of surfactants to facilitate the washing-out process when dyeing. In order to avoid that the fiber turns glassy (shiny) a matting agent in the form of titanium dioxide, or silicates are added, also optical brighteners are added. For the polymerization one needs small amounts of metal catalysts and at the end of polymerization one also needs a “catalyst-poison” in order to get the correct chain lengths.
== Potential impacts ==
Petroleum, the main ingredient in manufacturing polyester, is a non-renewable resource and mining for petroleum destroys natural habitats. That is to say that petroleum takes millions of years to form, and is currently being extracted from the earth for industrial uses faster than it can be replenished. The declining petroleum supply is the source of much debate—British Petroleum (BP) reports that there are 1,333 billion barrels still available to pump (enough for 40 years at current usage rates).[5] Other sources state that supply is overestimated and that reserves are about 30% lower than widely reported.[6]
The manufacturing process for polyester is fully chemical, energy intensive and releases greenhouse gasses into the environment.[7]In the production of polyester, the main ingredients used are terephthalic acid (TA) or dimethyl terephthalate, which are reacted with ethylene glycol, based on bromide-controlled oxidation.[7 ] The production of polyester emits emissions to air and water, which include: heavy metal cobalt; manganese salts; sodium bromide; antimony oxide; and titanium dioxide.
Antimony is of particular concern, since it is a toxic heavy metal known to cause cancer under certain circumstances and is a suspected reproductive toxin.[7] The function of antimony in the production of polyester is as a catalyst in the oxidation process. But it is not absolutely necessary for polyester production, and alternate non-antimony catalysts are available.
Europe meets its oil consumption/needs by importing from foreign sources: 41% from the Russian Federation, 26% from Africa, 16% from the Middle East—14% comes from Europe—thus requiring transportation over long distances.[8][9] Fuel released by vehicles used to transport the oil causes pollution and CO2 emissions.
== Alternatives to virgin polyester ==
=== Biopolymer fibres fibers ===
==== Polylactide (PLA) ====
Polylactide (PLA) is a renewable thermoplastic and a polymer. It is derived from the starch of plants such as corn, sugar cane and sugar beet. PLA is biodegradable, as it decays as a result of exposure to heat and moisture. It decomposes forming carbon dioxide and water, which present no danger to the environment.[16][17]