Surface modification of aramid yarn by atmospheric pressure plasma: Reinforcement and floating properties

Today, aramid fibers have extensive applications ranging from wearable textiles, tires, and ropes to reinforced and protective materials. However, further extension of their applications requires surface modifications regarding wettability and mechanical properties. Accordingly, the present study introduces a single-step, low-cost, and rapid method to improve the performance of aramid yarn using atmospheric pressure plasma. To this end, the plasma treatment was performed using argon and acetone as the main working gas and a liquid precursor, respectively. The results of the FE-SEM and AFM analyses revealed the formation of a thin nanostructured layer on the surface of the yarn, leading to increased surface roughness. Investigation of the chemical structures of the yarn through FTIR, EDS, MAP, and TGA analyses confirmed the significant changes in surface structures followed by the formation of the new carbon-containing group. The XRD analysis of the crystalline structures also indicated a major change in the crystalline phases of the samples. Overall, the plasma-modified aramid yarn showed excellent buoyancy functionalities and waterproof properties. Moreover, the tensile strength of the yarn was improved after the treatments. The results confirmed the development of a promising, environmentally-friendly, single-step, and low-cost approach for the surface modifications of yarns

Effect of voltage shape of electrical power supply on radiation and density of a cold atmospheric argon plasma jet

In this work, we investigated generating argon cold plasma jet at atmospheric pressure based on dielectric barrier discharge configuration using three electrical power supplies of sinusoidal, pulsed and saw tooth high voltage shapes at 8 KHZ. At first; we describe the electronic circuit features for generating high voltage (HV) wave forms including saw tooth, sinusoidal and pulsed forms. Then, we consider the effect of voltage shape on the electrical breakdown. Relative concentrations of chemical reactive species such as Oxygen, atomic Nitrogen and OH were measured using optical emission spectroscopy. Using a simple numerical model, we showed a HV with less rise time increases electron density, therefore a cold plasma jet can be produced with a minimal consumption electrical powe

Generation and investigation of plasma ball and plasma jet by microwave at atmospheric pressure

In this work, we first produced microwave plasma ball, then changed the ball into a microwave plasma jet by flowing a working gas through a nozzle. The effect of working gas on the thermal characteristics of the plasma ball and atmospheric pressure microwave plasma jet was investigated. We used resonant absorption scheme by a metallic antenna inside a chamber in which led to the ionization of surrounded gas forming the plasma. A commercial magnetron at 2.45 GHz was used to produce plasma by various gases such as argon, nitrogen, air and argon/nitrogen composition. For analysis and identification of reactive species in the plasma, the optical spectroscopy (OES) was carried out. Optical emission spectroscopy of the plasma ball/jet revealed the presence of reactive neutral and excited atomic and molecular components generating from working gases and antenna materials. The antenna material has a significant impact on the jet length, so that maximum length of the plasma jet was observed in Fe-Ni antenna. The results of the experiments revealed that there is no significant change in the plasma jet length versus different gas flow rates and applied powers, while it is more sensitive to the gas type and antenna material

Cell repellent coatings on inner walls of tubes by means of transporting discharge in atmospheric pressure.

www.springerlink.comInternational audienceWe report a method to obtain biocompatible PEG copolymer coatings inside High Density Polyethylene (HDPE) and Pyrex tubes, which was successfully developed by using a transporting discharge. The latter being a dry process, it is easier to apply as compared to the conventional multistep wet chemical techniques. The results presented in this paper show that for a 70 cm tube good cell repellent properties as compared to the control was obtained for the entire length of the tube. The best nonfouling properties with respect to CT-26 (colon cancer) were obtained for coatings presenting the best retention of ether functionalities from the DEGME monomer i.e. between 5-25 cm downstream of the tube. These results are interesting for surface modification of biomaterial and biomedical devices which present hollow bodies