[iantgotaclue]

Hello
I am trying to understand the differences between polyester, spandex and Polyurethane. In short is it possible for a clothing label to say the material is 100% polyester and also contain spandex? I asked them this and they said as spandex was made from polyester this made the material that was both polyester and spandex a 100% polyester material. I dont really understand the differences between these chemical products to know if this is true. I thought spandex was a polyunsaturate product and that polyester is not polyurethane but that polyurethane can contain polyester. It is rather confusing to me when i just think of them all as petro chemical products?

thanks for any guidance.

[pgk]

Spandex, Lycra, etc. are usually made of polyurethane co-polymers with either saturated or unsaturated monomers.
By their turn, polyurethanes are condensation polymers of polyisocyanate monomers with either polyether or polyester polyols.
Furthermore, all these polyols and monomers are made from petrochemicals.
I hope to have helped you, to clarify the issue.

[P]

I am trying to understand the differences between polyester, spandex and Polyurethane.

Spandex is just a brand name I think. Maybe that is just polyester or a blend with other polymers. Naming copolymers can be complex so maybe they just label them as polyester to cover all possibly copolymers and blends of it in their fabric.

Polyester and Polyurethane are 2 different polymers... determined by the repeat unit in the polymer chain being different. You can look up the structures of Polyester and Polyurethane pretty easily to show you the difference.

[pgk]

Yes! 
Spandex, Lycra, Elastan, etc. are proprietary names and refer to elastic fibers that are mainly used for manufacturing of athletic ware. 

[Corribus]

Polyester refers to a class of polymers, not a specific one. They are classified by having repeating ester linkages, but that leaves a lot of room for variation, especially when copolymers are considered. As such, a lot of different synthetic polymers, including many (but not all) polyurethanes, are classified as polyesters. Spandex is a trade name for an elastic block copolymer that includes polyester (polyurethane) segments and polyether segments. Therefore both Spandex and polyurethane may be considered polyesters.

You can read more about Spandex here:

https://pubs.acs.org/cen/whatstuff/stuff/7707scitek4.html

By the way, don't Google "Spandex" at work and display the available images, lol.

[DrCMS]

Polyester refers to a class of polymers, not a specific one. They are classified by having repeating ester linkages, but that leaves a lot of room for variation, especially when copolymers are considered.

Yes

As such, a lot of different synthetic polymers, including many (but not all) polyurethanes, are classified as polyesters.

No

Spandex is a trade name for an elastic block copolymer that includes polyester (polyurethane) segments and polyether segments.

No it is not.  Spandex/Lycra is a polyurethane made from a polyisocyanate (hard segment) and a polyol (soft segment).  The polyol in Spandex is usually a polyester but it could be a polyether or a mix of the two.

Therefore both Spandex and polyurethane may be considered polyesters.

No.  Spandex is a polyurethane and polyurethanes have carbamate links not simple ester ones and so are not classed as polyesters.  Polyurethanes can contain a polyester chain but many do not.

[Corribus]

Well I disagree with you. But I guess that kind of sums up the thread, when professionals can't even come to consensus about polymer classification.

[pgk]

Please, permit me this comment:
Both of you are right by disagreeing!
Polyurethane is not polyester but a polyester polyurethane is a polyester, too. Especially, if ester groups quite more than carbamate ones, e.g. a polyurethane polymer that is prepared from poly(ethylene succinate) 10,000.
Besides, a carbamate group is half an amide and half an ester that can be hydrolyzed, hydrogenated, transesterified, transamidated, etc.

[P]

Well I disagree with you. But I guess that kind of sums up the thread, when professionals can't even come to consensus about polymer classification.

LOL quite - As I tried and failed to get across in my first post....  nomenclature of co-polymers and branded systems is complex.

With co-polymers of 2 well know polymers it still isn't clear. The name can change depending upon how much info is conveyed. i.e.  -  is it a branched, dendric, block or a statistical co-polymer. What are the ratios of the monomer in the co-polymer, what is it's molecular weight,  etc... the copolymer's name will be the same, but the end result could be a wide range of things.