Saminathan Ratnapandian

Equipment

1. Plasma machine

An atmospheric plasma treatment system APC 2000 (Figure 4.2), manufactured by Sigma Technologies International (Tucson, Arizona, USA), operating at ambient temperature, was used. Figure 4.3 shows the two aluminium electrodes mounted above a ceramic-coated aluminium electrode (in the form of a roller) to which the fabric (face side up) was attached using masking tape [161]. The operating frequency and roller speed were 90 kHz and 25 rpm respectively. The voltage range used was 1.8–2.2 kV with a maximum power input of 5 kW.

Figure 4.2 APC 2000 atmospheric plasma treatment system [161]

Figure 4.3 APC 2000 side view showing position of electrodes [161]

2. Padding mangle, steamer and dryer

The equipment described in Sections 3.2.1, 3.2.2 and 3.2.3 were used for padding, steaming and drying. The operating conditions were the same as adopted in Chapter 3.

4. Materials

The fabrics, mordant-dyes and required chemicals described in Sections 2.2.1.1, 2.2.1.2 and 2.2.1.3 were used in this investigation.

5. Methods

This section describes the plasma pretreatment and subsequent padding and evaluation processes.

1. Plasma pretreatment

The electrodes were thoroughly cleaned using ethanol to remove residual traces of glue and other debris. A fabric sample (wool or cotton) of size (40 cm x 40 cm) was attached to the roller electrode using masking tape. Care was taken to ensure that the attached fabric passed freely between the electrodes. Fabrics were treated with plasma for two exposure times of approximately 7 and 14 seconds based on earlier research [160].
Exposure time was calculated considering the number of passes through the plasma machine. Two plasma gases (100% helium and a mixture of 95% helium and 5% nitrogen) were evaluated. It was expected that the plasma generated from the mixture of gases would be more reactive. A flow rate of 14 litres per minute was used in both cases. In order to obtain a patterning effect by partially blocking the plasma, a white copy paper was applied as a mask (Figure 4.4). Treated samples were kept in a clean
air-tight environment with minimum handling to prevent contamination prior to evaluation or padding.


Masking tape


Fabric

Paper mask

Figure 4.4 Schematic sample set-up for plasma treatment

2. Padding

Padding of cotton and wool fabric samples pretreated with plasma was carried out as described under Section 3.3.1. Post-mordanting and the optimum parameters determined in Chapter 3 and shown in Table 4.2 were adopted.

Table 4.2 Mordant concentration and sequence for padding with 10 g/l dye