**2.2.2 Plasma dosage**

The power of discharge, velocity, number of passages of the fabric between electrodes were variable corresponding to calculated discharge dosages from 400 to 3600 W.min.m-2 (Table 1). The dosage was calculated according to the following equation (Eq.1):

$$Dosage = \frac{\mathcal{W} \times P}{V \times L} \tag{1}$$

Equation 1. Plasma dosage determination, where W = power (Watts); P = number of passages; V = velocity (m.min-1) and L = width of treatment (0.5m).


Table 1. Experimental parameters of DBD plasma and dosage applied.

#### **2.3 Characterization of DBD treated fabrics and structural analysis 2.3.1 Water drop absorption test**

In order to evaluate the wettability of the untreated and of the plasmatically modified polyamide woven fabrics, a water-drop test was applied by measuring the time for its complete absorption into the material.

Polyamide 6.6 Modified by DBD Plasma Treatment for Anionic Dyeing Process 245

a)

b)

Fig. 2. Dyeing conditions used for (a) Processes 1 and 2 (b) Processes 3 – 7, according with

The whiteness (Berger formulae) of the polyamide fabric after DBD treatment and color intensities of the dyed fabrics were measured by using a Datacolor Spectraflash SF 600 Plus

The average of three reflectance measurements, taken at different positions on the dyed fabric, was adopted. The relative color strength (K/S values) was then established according to the Kubelka-Munk equation, where K and S stand for the light absorption and scattering,

> <sup>2</sup> (1 R)

The washing fastness was evaluated in accordance with stipulated in standard ISO 105 C06, method A1S, at temperature of 40ºC. The rubbing fastness was evaluated according to

2R . (2)

CT spectrophotometer for D65 illuminant, over the range of 390-700 nm.

*K S*

Table 2

respectively:

**2.5 Whiteness and color strength** 

**2.6 Washing and rubbing fastnesses** 

standard ISO 105 X12:2001.

This test is performed in order to check the efficiency of the plasmatic treatment in function of the experimented dosages.

#### **2.3.2 Contact angle measurement**

Dataphysics equipment using OCA software with video system for the capturing of images in static and dynamic modes was used for the measurement of contact angles of the water drops in polyamide 6.6 fabrics.
