Dyeing behavior of atmospheric dielectric barrier discharge AR-O 2 plasma treated poly (ethylene terephthalate) fabric
Low-pressure glow discharges are efficient in generating uniform plasmas. They have been applied in surface modification of varieties of materials. But most of these applications are limited to small-scales because of their reliance on vacuum equipments needed to sustain processes at low pressure. This work aims at commending a continuous surface treatment device, which meets the requirement of textile material surface modification by dielectric barrier discharge (DBD) at atmospheric pressure for industry production. In the experiment, quasi-glow-discharge, a glow-discharge like plasma, is produced under atmospheric pressure with the continuous simple device. Through the discharge of mixture of argon and oxygen, Ar-O2 (10:1), polyester fabric is continuously modified. The results reveal that the dyeability of the polyester fabric is dramatically improved. The spectral value (K/S) of the dyed polyester fabric is increased by about 50 %, and the relative dye up-take is also increased by about 18% after the treatment. The dyeing fastness of the modified material remains the highest degree. That is to say, the improvement of the dyeability does not degrade the dyeing fastness of the material at all. The study of scanning electron microscope (SEM) shows that the smooth and glossy surface of polyester fiber becomes rough after the treatment. The X-ray photoelectron spectroscopy (XPS) illustrates that Ar-O2 (10:1) discharge can help generate a few carboxyl groups in the polyester fiber surface. The improvement of dyeability is attributed to the reaction of coarsenization and the introduction of functional groups in the surface during the treatment. Producing approximately uniform plasma in simple operation and achieving satisfying surface modification of textile material, this kind of device would play an active role in the future technological textile industry.
Dielectric-Barrier Discharges. Principle and Applications
Dielectric-barrier discharges (silent discharges) are non-equilibrium discharges that can be conveniently operated over a wide temperature and pressure range. At about atmospheric pressure electrical breakdown occurs in many independent thin current filaments. These short-lived microdischarges have properties of transient high pressure glow discharges with electron energies ideally suited for exciting or dissociating background gas atoms and molecules. The traditional application for large-scale ozone generation is discussed together with novel applications in excimer UV lamps, high power CO 2 lasers and plasma display panels. Additional applications for surface treatment and pollution control are rapidly emerging technologies. Recent results on greenhouse gas recycling and utilisation in dielectric-barrier discharges are also discussed.
ROOM- AND HIGH-TEMPERATURE MAGNETIC PROPERTIES OF Sm(CobalFexCu0.088Zr0.025)7.5 (x=0.30) SINTERED MAGNETS
The effect of Fe content on room- and high-temperature magnetic properties of Sm(CobalFexCu0.088Zr0.025)7.5 (x=0-0.30) sintered magnets, prepared by the conventional powder metallurgy method, has been systematically studied. With increasing Fe content, the remanences BT and maximum energy products (BH)max at room temperature gradually increase and reach optimal values of 1.055 T with x=0.27 for BT, and 205 kJ/m3 with x=0.21 for (BH)max, respectively, and then drop sharply with further Fe increase. An excessive addition of Fe (x≥0.24) results in rapid deterioration of permanent magnetic properties due to the formation of a considerable amount of FeCo soft magnetic phase. It was found that the effect of Fe content on high temperature stability is huge. The lower the Fe content, the smaller the temperature coefficient of coercivity. When x=0.07, a temperature coefficient of coercivity of -0.14%/K (293-723 K) can be achieved, as compared with -0.23%/K for x=0.21. BT of 0.725 T, bHc of 517 kA/m, iHc of 764 kA/m, and (BH)max of 95 kJ/m3 at 723 K were obtained, and the B-H demagnetization curve remains a straight line.