**2. Experimental part**

#### **2.1 Materials**

#### **2.1.1 Fabric and dyes**

A 100% polyamide 6.6 plain weave fabric (105 g.m-2) was used as dyeing substrate. The samples were pre-washed with a solution of 1% non-ionic detergent at 30ºC for 30 minutes and then rinsed with water for another 15 minutes, before DBD treatment in order to minimize the contamination.

The dyes used were the following:

**Reactive dyes for cotton** - Levafix Red Brilliant E3BA (C.I. Reactive Red 147), Levafix Yellow CA (C.I. Reactive Yellow 26), Remazol Yellow Golden RNL (C.I. Reactive Yellow 27), Procion Crimson H-EXL (C.I. Reactive Red 231), Procion Yellow H-EXL (C.I. Reactive Yellow 138:1) and Remazol Blue Navy RGB (C.I. Reactive Blue 203).

**Reactive dyes for wool** - Realan Blue EHF, Realan Red EHF, Realan Yellow EHF and Lanasol Blue 3G (C.I. Reactive Blue 69).

**Direct dyes** - Sirius Orange 3GDL (C.I. Direct Orange 57), Sirius Scarlet KCF, Sirius Violet RL (C.I. Direct Violet 47) and Sirius Blue KCFN.

**Acid dyes** - Telon Blue MGWL, Telon Red A2FR and Rot M-6BW. All of them were kindly supplied by Dystar ®.

#### **2.2 Plasma treatment 2.2.1 DBD plasma machine**

242 Textile Dyeing

In order to achieve better dyeing results in polyamide fibers some trials are reported in the bibliography using new techniques for structural changes, being irradiation by means of

Low temperature plasmas via several gases such as oxygen, tetrafluormethane and ammonia were used for modification of fibers i.e. wool and polyamide 6. Dyeing of modified fibers was performed with several natural dyes and the dyeing rate of the plasma-

Polyamide 6 was treated with tetrafluoromethane low temperature plasma and then dyed with commercially available acid and disperse dyes. Acid dyeing results show that this type of plasma treatment slows down the rate of exhaustion due to an increase in hydrophobic groups at the surface originated by the type of gas used, without reduction of the amount of

The dyeing properties of disperse dyes on plasma-treated polyamide fabrics markedly increase comparing with untreated fabric by increasing hydrophobic attraction between

Polyamide 6.6 fabric was dyed with a disperse-reactive dyestuff and a covalent bonding with the fiber was proved to occur if supercritical carbon dioxide is used (Liao et al., 2000). Polyamide 6 materials irradiated with 193 nm ArF excimer laser developed micro-sized ripple-like structures on the surface, able to increase surface area and light diffuse reflection. Laser treatment is proved to be responsible by breaking the long chain molecules of polyamide resulting in an increase of amine end groups' content. Results revealed that dyeing properties of reactive dyes tested on polyamide fabrics improve after this treatment,

In the present work, polyamide 6.6 fabrics were treated with different dosages of an atmospheric double barrier discharge obtained in a semi industrial prototype equivalent to an industrial machine installed in a Portuguese textile plant [Pat. PCT/PT 2004/ 000008(2004)]. The structural and chemical modifications of fabrics were further analyzed in terms of X-Ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) techniques. Moreover, the tinctorial behavior (color strength, exhaustion) of the polyamide fabric dyed with different dye classes, namely reactive dyes for wool, reactive dyes for cotton, acid and direct dyes, was studied as well as washing and rubbing fastnesses.

A 100% polyamide 6.6 plain weave fabric (105 g.m-2) was used as dyeing substrate. The samples were pre-washed with a solution of 1% non-ionic detergent at 30ºC for 30 minutes and then rinsed with water for another 15 minutes, before DBD treatment in order to

**Reactive dyes for cotton** - Levafix Red Brilliant E3BA (C.I. Reactive Red 147), Levafix Yellow CA (C.I. Reactive Yellow 26), Remazol Yellow Golden RNL (C.I. Reactive Yellow 27), Procion Crimson H-EXL (C.I. Reactive Red 231), Procion Yellow H-EXL (C.I. Reactive

**Reactive dyes for wool** - Realan Blue EHF, Realan Red EHF, Realan Yellow EHF and

**Direct dyes** - Sirius Orange 3GDL (C.I. Direct Orange 57), Sirius Scarlet KCF, Sirius Violet

lasers and plasmas presented as promising solution.

dye absorption at equilibrium.

**2. Experimental part** 

**2.1.1 Fabric and dyes** 

minimize the contamination. The dyes used were the following:

Lanasol Blue 3G (C.I. Reactive Blue 69).

RL (C.I. Direct Violet 47) and Sirius Blue KCFN.

**2.1 Materials** 

disperse dye and the fiber (Yip et al., 2002).

treated wool was considerably increased (Wakida et al., 1998).

in what concerns both kinetics and equilibrium phases (Yip et al., 2004).

Yellow 138:1) and Remazol Blue Navy RGB (C.I. Reactive Blue 203).

A double barrier discharge was produced in a semi-industrial machine (Softal/University of Minho) functioning with air at normal temperature and pressure, using a system of ceramic electrode and counter electrode with 50 cm effective width, and producing the discharge at high voltage and low frequency.

Fig. 1. DBD plasma machine diagram.
