Preparation of Silver-Plated Para-Aramid Fiber by Employing Low-Temperature Oxygen Plasma Treatment and Dopamine Functionalization

Direct electroless silver plating of para-aramid (PPTA) is difficult due to its extremely low surface chemical energy. In order to facilitate the deposition of silver nanoparticles and to enhance the washing fastness, oxygen plasma treatment and dopamine modification were conducted before silver plating of PPTA fibers. Various techniques including scanning electron microscopy (SEM), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), X-ray diffractometer (XRD) and thermogravimetric analyzer (TGA) were used to characterize the surface morphology, chemical composition and thermal stability of the silver-plated PPTA fibers. Electrical resistance and silver content of the silver-coated PPTA fibers before and after standard washing were also studied. The results showed that silver nanoparticles were successfully coated onto the surface of PPTA fibers with and without plasma treatment, but the coating continuity and the electrical conductivity of the silver-coated PPTA fibers were greatly enhanced with the assistance of plasma treatment. It was also demonstrated that the washing fastness of silver-coated PPTA fibers was improved after plasma treatment as indicated by electrical resistance and continuity of the silver nanoparticles after various washing cycles. It was found that the electrical resistance of plasma-treated PPTA-PDA/Ag fibers prepared at an AgNO3 concentration of 20 g/L reached 0.89 Ω/cm and increased slightly to 0.94 Ω/cm after 10 standard washing cycles. The silver-coated PPTA fibers also showed stable electrical conductivity under 250 repeated stretching-releasing cycles at a strain of 3%.