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This information is for general knowledge. If you have a critical application check your requirements and make sure the rope is suitable. Different manufacturing processes change the feel, appearance, and strength of ropes so the strength figures I am giving are for comparison only. Some ropes have been coated with materials that improve handling or resistance to sun or chemicals. If you clean them harshly this coating could be damaged. Follow the manufacturers advice on the care of your ropes.

Materials used for Ropes:
Polyester

Polyester is sometimes called Terylene, Dacron, or Trevira, these are trade names for the same material. Polyester fibres and almost all nylon fibres are very fine and hair like, typically about 0.023 mm dia. These fibres are almost always white. It is virtually impossible to distinguish between nylon and polyester by appearance alone.

Polyester Physical Properties

Polyester has a specific gravity of 1.38 which means it does NOT float.

Polyester is very strong, it has a similar tensile strength to Nylon 6, and is slightly stronger than regular Nylon.

Unlike Nylon or Polypropylene, Polyester is not stretchy. Usually any stretch present in Polyester is minimized by pre-stretching during the manufacturing process. It also has low creep under load.

Unlike Nylon, Polyester retains its strength when wet.

Melting Point 240 degree Celcius. Varies with different composition

UV resistance is Excellent. Typically a polyester rope will only lose 10% of its breaking strength after 2 years of outdoor use. This is excluding cuts or severe abrasion.

Excellent abrasion resistance.

Polyester is non conducive to electricity.

Strength and Weight of Polyester Rope

Diameter		Weight		Average Strength
Inches	mm.	lbs per ft	kg per m	Pound	Kilogram
3/16	4.8	0.01	0.015	1 175	533
1/4	6.4	0.02	0.03	1 088	2 400
5/16	7.9	0.031	0.046	3 400	1 542
3/8	9.5	0.045	0.067	4 800	2 177
7/16	11.1	0.061	0.091	2 993	6 600
1/2	12.7	0.08	0.12	9 000	4 082
5/8	15.9	0.125	0.19	15 500	7 037
3/4	19.1	0.179	0.267	18 000	8 172
1	25.4	0.319	0.475	32 000	14 528

Polyester Chemical Resistance

Good resistance to Alkalis and Acids at room temperature. As the temperature increases, the resistance decreases.

Polyester has excellent resistance to Petroleum based products, Bleaches and Solvents. That doesn't mean it is not affected. Don't soak your lines in bleach for long periods, they will be weakened.

Polyester Uses

Among the conventional synthetic ropes available Polyester has the lowest stretch and best abrasion resistance.

It is commonly used for halyards and sheets. It also finds use for anchor rode. It is stiffer than nylon and not as soft to the hand.

Polyester rope or polyester combinations are often found for winches, capstans and block and tackles. Its low stretch and low creap.

It is extensively used for cargo lifting straps, and slings, where a stretch and bounce effect could de-stabilize a load.

There are a number of ropes offered that combine polyester outer braid with nylon inner core to get the abrasion and resistance to wear of polyester with the cushioning effect of nylon. It helps control the stretch of nylon in some towing ropes.

It is also combined with aramids again to provide protection and wearability, while the core provides more strength.

Advantages and Disadvantages of Polyester

Advantages

Good chemical resistance at regular temperatures
Excellent UV resistance
Polyester is slightly stronger than Nylon. However there is no strength loss when wet.
Low Stretch
Stiffer than Nylon, some braids can be made softer.
Well suited to Static Loads

Disadvantages

Polyester does not float.
Some braids of polyester are quite stiff and don't work very well in blocks.
Polyester is not suitable if the load is subject to jerking. It does not give as nylon does.

The safe loading of a rope is a 1/10 to 1/12 of its breaking strength. Remember that knots weaken a rope as does age, wear, chemical attack etc.

I try to be accurate and check my figures, but mistakes happen. Check the suitability of any material against the technical information provided by the manufacturer.

email me if you find mistakes, I'll fix them and we'll all benefit: Christine