Fibres

Nylon
Nylon is principally used in the building of spinnakers because of its low weight, of its good resistance to repeat folding and abrasion. However, its low modulus makes it too elastic for use in flat sails (Main, genoa, etc…).

Polyester
Polyester has excellent UV resistance, and good resistance to repeat folding and abrasion : it ages remarkably well.
These qualities, associated with its low, makes these fibres the most used in sail making. The modulus of polyester is however  too low for its application to high level racing sails.
Dacron is the  commercial name given by DuPont to its high range polyester for sails. Today the term Dacron is used for all the quality polyesters.
Polyester is used as a cloth ( Dacron) and a laminate to make panelled sails.

PEN (pentex)
This is a high modulus polyester: it is 60% less elastic than classic polyester (but  2 x kevlar 29). 
The PEN, because of its propertiescan't be tightly woven, it therefore has to be impregnated with a lot of resin which makes it brittle  and requires some care when using it.
When laminated its mechanical qualities and its moderate cost  give it a good quality/ price ratio for racing sails.
PEN is used sous forme of yarn and of laminate for panelled sails .

Kevlar
Fibre invented by Dupont in 1971, it is one of the Aramid family.
its module is 5 times greater than polyester, and almost 2 x PEN
There are several qualities of kevlar : 29,49,129,149,159. Today kevlar 49 is usually used in the sail loft because, as the module increases, the flex resistance diminishes.
Kevlar like the majority of aramids has low  UV and flex resistance.

Because of these different parameters this fibre with its exceptional  mechanical qualities is reserved for racing and particularly offshore racing .

Twaron
Twaron is also an aramid produced by Teijin, it is chemically and physiically similar to kevlar by Dupont. High modulus Twaron has properties very similar to Kevlar 49

Kevlar and Twaron is used in  laminates and in D4.

Technora
Technora is also from the aramid family, it is produced in Japan by Teijin. Its modulus is slightly lower  than kevlar 29, but its flex and UV resistance is better.
It is principaly used in X ply of laminates in addition to other fibers, such as carbon for example.

Technora is used in laminates and in D4.

Spectra
Spectra is one of the  polyethylene family, it is made by Honeywell (also by DSM under the name Dyneema).
IIt has very good UV resistance  (like polyester), high initial modulus (just 10%  less than Carbon), tough, and very good flex resistance . However this fibre stretches slowly under continuous load, this results in shape loss over time.
Spectra (or dyneema) is often used for large cruising yachts.

Spectra is also used in laminates and in D4.

Vectran
This fibre is derived from polyester, it is a liquid cristal polymer by Ticona.
Its module is equivalent to kevlar 29, its flex resistance is excellent, There is no flow  and it has good abrasion resistance.
Its resistance to UV is less than polyester or PEN, but, whilst the other aramids continuously degrade when exposed to UV Vectran stops losing mechanical qualities after approximately  400H of exposure.
It is therefore longer lasting than kevlar, appreciated by long haul cruisers and for long races (Vendée globe, etc…).

Spectra is used principaly in D4.

Carbon Fibre
This is a very high modulus synthetic fibre, madefrom atoms of carbon. It is virtualy unaffected by UV, and is extremely stiff.
The different variations of this fibre range from a compromise of very high modulus/ fibre more brittle, to an elasticiy compared to aramids but giving a more tolerant and longer lasting fibre.
carbon is used for inshore and offshore racing. It is often associed with other Fibres.

Carbon is used in laminates and in D4

Films

the film the most used are mylar films, otherwise known as polyester films. They exist in 0.5 , 0.75 or 1 mm.

Taffetas

This is woven polyester very fine and light used to protect laminates and membranes.