Impact of ageing factors on the performance of novel viscoelastic polyurethane foams utilized as seals in respiratory protective devices

This study explores the impact of ageing factors - i.e., perspiration, disinfection procedures and ultraviolet radiation - on the structural and performance characteristics of novel viscoelastic polyurethane foams specifically developed for use in seals for respiratory protective devices (RPDs). The investigation includes an analysis of resilience, compression set and recovery time to ascertain the influence of the chosen factors on the foam's mechanical properties. Furthermore, an in-depth exploration of the foams' thermal properties and chemical structure was carried out using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR), respectively. The influence of the ageing factors on the foams' microstructure was scrutinized via scanning electron microscopy (SEM), supplemented by assessments of colour change and contact angle alterations. The experimental results were contextualized within the existing literature, with particular attention to the desired attributes of RPD seals composed of these newly engineered materials. Recommendations for use were then formulated.