Abstract: Acrylic acid(AA) and sodium styrene sulfonate(SSS) were grafted onto poly(ethylene-co-tetrafluoroethylene)(ETFE) film by pre-irradiation technique using electronic beam from a 2 MeV accelerator at room temperature. A humidity sensing film with strong acid and weak acid groups was prepared. Infrared spectroscopy analysis of the grafted film confirmed the existence of sulfonate and carboxylic acid groups in the grafted film. Thermal and chemical properties of the grafted films were investigated. The crystallinity and static contact angle of the grafted films decrease, meanwhile the hydrophilicity of the grafted films increases with increasing grafting yield. A resistive-type humidity sensor was prepared using the grafted film, and its electrical response to humidity was examined. The resistive of the sensor changes linearly by 4 orders of magnitude over almost whole humidity range(5%—98%RH). Furthermore, the sensor exhibits a quick response(absorption: less than 1 min; desorption: less than 2 min) and small hysteresis(less than 2%RH).

Key words: Pre-irradiation grafting, Acrylic acid, Sodium styrene sulfonate, Poly(ethylene-co-tetrafluoroethylene)