Influence of the Ozonation Process on Expanded Graphite for Textile Gas Sensors

In view of the growing demand for flexible, conductive and functional materials for textile gas sensor applications, the effects of ozonation on the properties of expanded graphite (EG) in textile structures were analyzed. Four types of fabrics (cotton, polyamide, viscose, para-aramid) coated with pastes containing EG, which had previously been subjected to a 15-min and 30-min ozonation process, were examined. The paste was prepared using Ebecryl 2002 and the photoinitiator Esacure DP250 and then applied by screen printing. Surface resistance, scanning microscopy and wetting angle analyses were performed. The results showed that short-term ozonation (15 min) notably improved the electrical conductivity and adhesion of EG to the textile substrate, while longer exposure (30 min) led to deterioration of the conductive properties due to excessive functionalization and fragmentation of the conductive layer. The lowest surface resistance was observed in the sample subjected to 15 min of ozonation. The conclusions indicate that a properly controlled ozonation process can increase the usability of EG in sensor applications, especially in the context of smart clothing; however, the optimization of the modification time is crucial for maintaining the integrity and durability of the conductive layer.