**2. Experimental work**

#### **2.1 Sample preparation**

#### **2.1.1 Woven polyester fabric**

A 100 % Polyester (PET) woven fabric of density 284 g/m² with a thickness of 0.56 mm and 63.5% porosity was used for the study. The PET woven fabric was cleaned to be free from surface impurities and spinning oil. The cleanliness of the PET samples was checked by

Atomic Force Microscopy – For Investigating Surface Treatment of Textile Fibers 247

per m² of textile sample, expressed in kJ/m². The TP is related to the velocity of the

0.06 *<sup>P</sup> TP V L*

Plasma treatment was carried out at velocities (V) of 1 m/min, 2 m/min, 5 m/min and 10m/min. It was also performed at constant speed with varied electrical power (P) of 400 watts, 700 watts and 1000 watts. After plasma treatment, each plasma treated sample was

Effect of ageing on air-plasma treated PET fabric samples was observed by monitoring changes in water contact angle as well as surface topography of the samples, 20 days after plasma treatment. Ageing of plasma treated sample was carried out in two different ways: *Without light:* Plasma-treated samples were kept folded in aluminium foil and stored in

 *With light:* Plasma treated samples were kept open in laboratory conditions allowing them to be in contact with light. Laboratory conditions with a temperature of 20 ± 2°C

The plasma treated PET samples were immersed in aqueous conditions at 90°C for 30

As ageing with time causes loss of hydrophilic species formed by plasma treatment (Krump, 2005), immobilizing a hydrophilic oligomer like PEG -poly(ethylene glycol) immediately after plasma treatment would perhaps yield a more durable hydrophilic treatment. PEGpoly(ethylene glycol) has been used for surface modification because of its unique

PEG of molecular weight 1500 g/mol , i.e PEG 1500 from Fluka chemicals was immobilized on cleaned-untreated PET fabrics as well as plasma treated PET fabric samples using padding and curing method. For the padding process the open-width PET fabric was passed through an aqueous solution of PEG 1500 in water and through two squeezing rollers (see Fig. 13). At a squeezing pressure of 4 bars, the weight pick up remained almost constant around 56%.

In a previous paper Leroux and al. ( Leroux, 2006) showed using AFM in the LFM mode, that friction forces measured at the surface of PET fabric is doubled after a plasma

and relative humidity of 60± 10 % were maintained during the experiment.

**2.1.5 Effect of PET fabric dyeing conditions (High temperature conditions)** 

(1)

treatment (V) and the electrical power (P) of the machine, by the equation (Eq. 1):

separated from waste fabric and kept in aluminium foil away from light.

cupboard, in a small dark chamber to avoid contact with light.

P = Electrical Power (W) L = Electrode length (m)

**2.1.4 Ageing methods** 

V =Velocity of the sample (m/min)

minutes without the presence of any dye.

**2.2 AFM tapping mode images** 

**2.1.6 Effect of adhesion of PEG 1500 on PET fabric** 

properties such as hydrophilicity and flexibility (Harris, 1992).

measuring the surface tension of final rinsing water (used to clean the PET samples), which remained constant and equal to 72.6 mN/m ,which is the surface tension of pure water.

#### **2.1.2 Sample preparation for plasma treatment**

The PET woven fabric was cut into square pieces of 50cm X 50cm on the basis of the electrode length of the plasma machine (50 cm). The speed of the fabric in the discharge zone could be varied through the control.
