Stern and Stern Inc.

SIMILARITIES: Fabrics composed of nylon and polyester fibers are similar in many respects.

They are similarly priced
Their melting points are nearly identical (approx. 480°F, 295°C)
They are similarly strong, with nylon having the edge.
They are quick-drying and mildew resistant.
Arguments exist on both sides about which fiber is better suited for UV resistance, and both will experience significant strength degradation over time with extended UV exposure.
Because nylon modestly outperforms polyester in abrasion resistance testing and is easier to dye, nylon is favored in outdoor luggage and sports applications.
Polyester is more resistant to stretching and shrinking than nylon, making nylon the preferred fiber for applications where stretch and shock resistance are required, such as in parachutes.
Both fibers are relatively non-hydrophilic, but being less moisture absorbent polyester is preferred in many anti-wicking applications, such as substrates for pressure sensitive diaphragms.
Both fibers retain their excellent properties under very low temperature conditions making either fiber an excellent candidate for upper and outer atmosphere applications.

DIFFERENCES: Where polyester and nylon diverge significantly is in their chemical behavior. They are chemical mirror images of each other. Polyester favors acidic environments (pH<7.0), while nylon favors alkaline environments (pH>7.0). Given exposure to the wrong chemical environment, either fiber will deteriorate rapidly, especially at elevated temperatures.