A photochromic nylon webbing for ultra-violet light sensing

Webbing structures are essential to the safety of engineering systems that routinely endure excessive sunlight exposure. Particularly damaging is the ultra-violet (UV) component of sunlight that may degrade polymer chains, thereby compromising mechanical strength. Despite considerable progress in structural health monitoring, UV damage sensors for webbing structures are still lacking. To fill this gap, we propose a simple and fast fabrication process for a nylon webbing structure that exhibits photochromic responses to UV irradiation. The photochromic webbing structure is fabricated by coating a nylon strap with a photochromic polymer. The photochromic webbing structure demonstrates high sensitivity to a wide range of UV irradiation energy. In addition, the webbing structure maintains photochromism even after photodegradation due to extreme UV irradiation (equivalent to 72 h of sunlight exposure). Our analysis indicates that a photochromic dye concentration of 1.00% is optimal for UV sensing. The proposed photochromic webbing could facilitate health monitoring of industrial, aeronautical, and aerospace structures.