Elastomultiester (T400®, elasterell-p)
A stretch polyester made of two different polyesters, typically PET and PTT, joined side by side in each filament. It gives mechanical stretch and good recovery without elastane. LYCRA® T400® is the best-known brand; 'elasterell-p' is the US generic name.
How it’s made
- 1Two polyesters with different shrinkage, usually PET and PTT, are extruded together as a bicomponent filament.
- 2Heat during processing makes the filament crimp into a spring-like coil, which provides the stretch.
- 3Used alone or blended with cotton, wool or polyester in wovens and knits. Some PTT is partly plant-based (e.g. DuPont Sorona®).
What to look for
- 'Elastomultiester' or 'T400' on the label for stretch trousers and denim that keep their shape.
- Note that PTT on its own is labelled as polyester, not elastomultiester.
- Partly bio-based or recycled variants, if the brand states them.
Pros
- Comfort stretch with good recovery
- More heat- and chlorine-tolerant than elastane
- Less bagging at knees and seat
Cons
- Less stretch than elastane
- Still a fossil-based polyester (unless bio-based content is stated)
- Blends are hard to recycle
Typical use
- Running:
- Occasionally in stretch woven shorts and trousers.
- Streetwear:
- Stretch chinos, denim, travel trousers, tailoring.
Sustainability
Being all-polyester, it can make mono-material garments that are easier to recycle than elastane blends, though this depends on the rest of the fabric. Bio-based PTT reduces but doesn't remove fossil input.