Study Of PET Fiber Surface Modification By Radio Frequency Atmospheric Pressure Dielectric Barrier Glow Discharge

The surface modification of chemical fiber and textile is an important subject with academic significance and practical profit. Plasma modification is a kind of environmental-friendly and dry processing method. So it has huge market potential and development prospects. Corona discharge plasma and dielectric barrier discharge (DBD) plasma are common technique applied to the surface modification of textiles but they are easy to damage them when processing fabrics. Low-pressure glow discharge plasma has to be operated in a reactor with vacuum system. So they are difficult to realize the industrial applications. In order to make it possible to industrialize the plasma modification of chemical textiles, atmospheric pressure glow discharge plasma (APGDP) and its modification technique become a hot point of research in recent years.In this paper, a self-design APGDP reactor, which was equipped with power supply of 13.56MHz, is introduced at first. This reactor used an argon-dominate gas as the working gas, as it is economically desirable to realize AGPDP applications with cheaper gases such an argon.Secondly, the discharge characteristics were investigated. As the RF power was switched on and the matching impedance suitably set, a pale-purple glow was initially generated near the wall. With increasing RF power, the pale glow evolved into bright white glow. Analysis of voltage and current wave forms suggested that both the voltage and current wave forms are predominately sinusoidal and discharge cycle was above 100 nanoseconds. Current-voltage curve showed that discharge current increase as voltage increase without any abrupt; The current-voltage phase angle suggested that the plasma evolved from being predominately capacitive to predominately resistive. Discharge mode was essential an abnormal glow discharge plasma.Thirdly, research was focused on the surface modification of PET fiber using this set up. The PET fibers were grafted with citric acid and acrylic acid in different concentration respectively. Surface contact angle measurement showed that water contact angle on PET fiber decreased after grafting with citric acid and acrylic acid. The surface wettability are all improved, besides surface wettability increased with the concentration of grafting solution increasing. Acrylic acid grafted PET fibers got a better wettability than citric acid grafted ones , PET fiber pretreated by plasma obtained a lower surface contact angle than that without plasma pretreatment.The Surface composition of grafted PET fiber was characterized by ATR-FTIR. THE results showed that there were no obvious differences between ungrafted and graft PET fiber in the spectra ,except that the typical peak of-OH in 3100cm^-1 appeared in both Citric acid treated PET fiber and Acrylic acid treated PET fiber indicated citric acid and acrylic acid had been successfully grafted on the surface of PET fiber. But the small absorbance ratio of -OH peak to other peaks proved a poor graft in both citric acid grafted PET fiber and Acrylic acid grafted PET fiber.The surface morphology of the PET fiber before and after surface modification was extensively studied by SEM. The SEM Picture figured out that the roughness of the surface of PET fiber increased after plasma treatment .There were big changes on the surface of plasma grafted PET fiber after grated with a acrylic acid. A thin film of Acrylic acid was obviously observed for acrylic grafted PET fiber.Overall, PET fiber is well modified by surface grafting with citric acid and acrylic acid (AAc) though RF APGDP device. Wettability of grafted PET with citric acid and acrylic acid improved showed by water contact angle measurement .FTIR and AEM results indicated that there two graft monomers were introduced on the surface of PET successfully. This approach could have great application potential for continue surface modification of fibers, cords or other textiles.