The man-made fibre is, apart from raw material production, the first step in the textile supply chain, followed by weaving, dyeing, printing and finishing, conversion to the end product, the use phase, the post-consumer waste phase, followed by recycling, incineration or landfill. All these steps may result in emission to air, water or land.
If industrial installations and operations are concerned, these will have to meet the legislation in place. Sustainability is also a key priority for these operations. Dramatic improvements have been made in dyeing and water contamination. But also the man-made fibre producer has contributed to this by supplying fibres which are dyed during the fibre production process, eliminating the need for water and energy-intensive dyeing at a later stage.
In many cases the product-use phase is even more important than the production phase regarding sustainability. Is the product consuming a lot of energy during use, or is the product saving energy? The greatest application of fibres is in textiles and several studies on the energy use during a garment lifecycle have shown that consumer use (laundering, ironing) was the predominant factor accounting for a multiple of the lifecycle energy compared to all stages of manufacturing. In general man-made fibres can be laundered at low temperatures, with large energy savings.
Man-made fibres reinforcement of composites allows dramatic weight savings in transportation like aircrafts and cars resulting in huge energy savings. Fibres are applied in car tires reducing rolling resistance, resulting in fuel saving during a tire life time.
And finally there is the post-consumer waste phase. When non-renewable raw materials are used into a product, the key to improved sustainability is in many cases recycling. Of course, provided, that collection and recycling systems are efficient and do not consume more non-renewable energy than is gained from the recycled product. A typical example of post-consumer waste recycling is the polyester drink bottle recycling. Carbon emissions associated with making polyester fibre from used PET bottles are substantially less than the emissions associated with fibre made from virgin chemicals. By now, over 70% of polyester staple produced in the European Union is made from recycled materials, mainly PET bottles but also factory waste.
Any textile waste which cannot be recycled can be efficiently incinerated with electricity and heat recovery, because of the high calorific value of man-made fibres.