Dacron® (Polyethylene Terephthalate)

Following its development in 1950 by DuPont, one of the world's largest scientific manufacturing companies, Dacron® has become the sail cloth most commonly used aboard recreational and cruising vessels around the world.(1)  Proponents applaud its durability, reasonably low stretch factor, low absorbency rate, high resistance to both UV rays and abrasion, and comparatively low cost.(1) (2) Since DuPont's patent has long since expired, Polyethylene Terephthalate woven sailcloth is also sold as sailcloth under other trade names, like Terylene, Tetoron, Trevira, and Diolen.(7) 

Tightly woven Dacron sailcloth
Magnified image of Dacron sail weave. http://www.doylesails.com/design/fabric.html

Dacron®'s cloth weave consists of a looser set of straight fibers oriented in the direction of the highest stress (so that they stretch, rather than separate, as the wind pulls on the sail), encapsulated by tightly woven strands (see above photo).(5) Beyond this tight weave, the unique qualities of Dacron® come from the chemical makeup of the fibers themselves. To learn about the synthesis of Dacron® fibers, see how Polyethylene Terephthalate strands are made.

Dacron® Properties 
   Modulus of Elasticity  Tensile Strength Creep Flex Resistance UV Resistance
Upwind Preference
 High  High  Low  High  High
 Medium  Medium  Medium  Negligible  High

My research was unable to uncover direct, clear, proven links between specific elements of Dacron®'s structure, and its observable properties. This is not to say that such links don't exist, clearly they do, but rather that, given the constraints of this project, I was unable to uncover them.

Click the chemical structure of PET to see how it's synthesized:PET
Subpages (1): PET Synthesis