Study on the thermal damage traces of common textile fibers after simulated transient thermal exposure in gas explosions.

Gas explosions often result in the loss of biological evidence. This is due to transient thermal exposure and extreme destructiveness. Such conditions pose significant challenges to the identification of suspects and the reconstruction of their behavior. Clothing fibers act as direct thermal carriers. They retain residual damage traces critical for inferring an individual's exposure to explosive thermal processes. However, existing steady-state research does not replicate the "millisecond-scale, kilo-degree" transient thermal effects of explosions. This study utilized a custom-built apparatus and a full-scale platform. It simulated a 1200 ± 100°C environment to systematically characterize the thermal response of six typical fibers: cotton, ramie, mulberry silk, PET, nylon, and PET/cotton (80/20). Results indicate: (1) Intrinsic thermal properties dictate damage modes. After transient thermal exposure, natural fibers (cotton, ramie, and silk) show chemical pyrolysis, like dehydration, carbonization, and fibrillation. Synthetic fibers (PET and nylon) mainly undergo physical phase transitions, such as melting and shrinkage. (2) Physical attributes modulate the damage progression. Material thickness delays core heating via thermal inertia. Surface fuzz accelerates thermal response due to the high specific surface area. Darker dyes exacerbate damage by increasing heat absorption. (3) Full-scale experimental results demonstrate that the thermal damage traces of fibers in gas explosion scenes are consistent with the traces of long-duration heat exposure simulated in the laboratory. This study summarizes and establishes criteria for identifying fiber thermal damage under transient high-temperature conditions, providing an objective scientific reference for associating suspects with the explosion scene and facilitating crime scene investigations in gas explosion cases.