Impact of Ultraviolet Radiation-Induced Damage to Hair Fiber Integrity: A Multi-Technique Physicochemical Characterization of Surface and Cortex Properties

This study investigates the impact of ultraviolet (UV) radiation on hair fiber integrity, comparing it to the effects of bleaching. It simulates solar radiation damage over a Brazilian summer and finds that UV exposure causes cuticular damage similar to bleaching, with increased cystic component oxidation and decreased hydrophobicity. After 192 hours of UV exposure, hair shows significant mechanical degradation, with reduced force at 20% elongation and elongation at break, indicating more pronounced damage than chemical oxidation alone. However, the structural protein degradation from double bleaching is more severe than that from UV radiation, despite comparable enthalpy changes after 192 hours of UV exposure.