ABSTRACT
The schematic diagram of the plasma reactor at BTRA is shown in Fig. 3.1. The system operates in continuous mode where online treatment of fabric is possible. The length of plasma zone (total length of electrodes in the direction of fabric movement) is 12 cm and width is 55 cm. The minimal possible gap of 0.5 mm was kept in-between the top and bottom electrodes since previous research (Kale, 2010) showed better efficiency of plasma treatment at narrower inter-electrode gap. Carrier gases like helium and argon are often added to the polymerizing gas plasma mixture to increase homogeneity and stability of plasma. Helium has certain properties like highenergy metastable state, thermal conductivity, and chemical inertness which
reduce instabilities in the plasma. Though argon is widely used for deposition of plasma polymers, in this study, we used helium, argon and mixture of both for generating uniform and homogeneous non-thermal plasma. In our study, liquid monomer (HMDSO) at a fixed flow rate of 0.65 ml/min was fed continuously to each evaporator. At the evaporator, monomer (HMDSO) was vaporized to a gaseous form at a temperature of about 150°C and then the monomer in vapour phase was mixed with carrier gas. This mixture of inert gas and vaporized monomer was then fed to the electrode system where electrical power was applied to the electrodes to generate plasma. Various experiments were carried out on different fibres to capture the data on various plasma process parameters. The discharge power density for plasma generation was kept in the range of 3.0 W/cm2 to 7.6 W/cm2 in different experiments. In each experimental series, the plasma exposure duration was varied from 30s to 320s. The plasma is generated from the mixtures of HMDSO (0.65 ml/min), with helium, argon and He + Ar mixture. Experiments were carried out at different power as mentioned below and their corresponding plasma density (power per unit area) is also given here.
