The relationship between nylon and humidity in the air and, in general, water is essential to explain the success of this material. Just like a sponge, a nylon product absorbs and expels water, adapting to percentage of environmental humidity up to a maximum of 8.5%, as illustrated in graph 2. Therefore the mechanical characteristics of the product vary according to the water content.
Temperature, after water, is the second great physical factor that not only influences the rigidity and flexibility of nylon, but also irreversibly deteriorates it over time. Temperatures over 60°C start to damage the product. A comparison of performance ratings of standard nylon and heat-resistant nylon demonstrates that the latter resists without altering any physical properties up to temperatures of 130° C as shown in graphs 1 and 2.
Unlike high temperatures that soften the material, low temperatures harden it through to the fragility levels shown in graph 4. The formulas suited to working at low temperatures are known as “toughened” and graph 3 highlights the least rigidity at low temperatures. Warning: due to the effect of the toughening agent, the product loses its V2 rating and is then classed as HB.
Exposure to the sun, and in particular to UV rays, is another contributing factor to the deterioration of nylon. The graph shows the results of an accelerated ageing test, comparing standard material with that protected against UV rays with self-extinguishing class V2 in accordance with UL 94 standards. As can be seen, already after 300 hours of exposure to sun, the standard product halves the percentage of elongation at fracture, while the product protected against UV maintains the same elongation value even after 1500 hours. Considering these and other data supplied by manufacturers, it can be concluded that the protected material can resist, if applied correctly, outdoors even for prolonged periods of time, for as long as ten years.
ALONGATION AT BREAK (%)
- UV-V2 Resistant
- Standard material
WOM EXPOSURE TIME (h)