Materials used for Ropes:
Nylon (polyamide)

Nylon is a generic designation for a family of synthetic polymers known generically as polyamides

Widely used for many products, it can be spun, moulded and machined.

Nylon Physical Properties

• Specific Gravity: 1.13, Nylon does not float
• Polyamide is durable and strong with excellent abrasion resistance
• Nylon will stretch alot before breaking. It is quite elastic and a good shock absorber. This makes it a good choice for live loads, including towing and anchoring.
• Melts instead of burning, if burned emits some cyanide.
• Good strength to weight ratio
• Transparent to infrared light
• Maximum Temperature: 210°F 99°C, Minimum Temperature: -94°F -70°C
• Melting Point: 420°F 216°C
• Tensile Strength: 5,800 psi
• The UV resistance of Nylon is good.
• When dry, polyamide is a good electrical insulator. Because it absorbs water the properties of Nylon can change when it is wet.

Nylon Chemical Properties and Rot Resistance

• Good resistance to Oil and Organic Solvents, Formaldehyde and Alcohols
• Poor resistance (not recommended for use with) Phenols, Alkalis, Iodine and Acids, Chlorine is also to be avoided.
• Nylon is resistant to insects, fungi, animals, as well as molds, mildew and rot.
• Nylon doesn't burn but when it break down in fire it forms hazardous smoke, or ash, usually containing hydrogen cyanide.

Nylon Rope Strength and Weight

The safe loading of a nylon 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.

Nylon Degradation

Nylon is sensitive to high temperatures and will degrade releasing toxic materials including cyanide.

It it however resistant to UV light.

Because it absorbs water it is liable to stain. This is not necessarily harmful but can be unsightly.

Nylon rope

Nylon is usually used as monofilament. I have not seen it being chopped and re-spun. Nylon rope comes either braided or twisted.

It can be made from thicker or thinner strands which will affect its feel and appearance.

It is available in many colours.

Some nylon rope is available with water repelling coating which reduce water absorption.

Advantages and Disadvantages of Nylon Rope

Advantages

• Nylon can be made to be very lustrous, semilustrous or dull and can be made quite soft to the hand
• Polyamide has good UV resistance
• It is relatively inexpensive.
• Its quite resistant to solvents and oil, but does not like strong bases and acid.
• Resists rot and mildew but can stain.
• Doesn't burn
• Nylon is strong, resistant to abrasion
• Nylon is elastic and stretches UP TO 40% (more commonly 15-25%). It makes good mooring, anchor and dock lines. It is also widely used as towing lines for this reason.
• Can be made to feel soft and pleasant to the hand.

Disadvantages

• It sinks
• Releases harmful chemicals when it degrades in high heat.
• Because it is quite stretchy, it is not suitable where a line needs dimentional stability such as rigging.
• Nylon has been know to shrink and because of this it is usually heat set.
• Nylon looses strength when wet, Sometimes as much as 20% of dry strength.
• If nylon is repeatedly cycled at high percentage of its breaking strength, it generates a large amount of internal heat, which degrades the performance of nylon and can cause failure at high loads, such as anchor rodes during a storm. For more on this Article by Steve Dashew, taken from Cruising World, aug 2001

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.