Hydrophilicity Analysis Essay

3. Result and discussion

3.1 Effect of Oxygen plasma-hydrophilicity Analysis

The hydrophilic nature of the Oxygen plasma treated cotton fabrics was investigated by measurements of contact angle and optical microscope image. Fig. 2(a) shows the variation of the contact angle for the untreated and Oxygen plasma treated cotton fabric at different treatment times. The contact angle of untreated fabric found 1490 (fig.2 (b)) it is noted that the hydrophobic nature due to lack of polar groups on the substrate. After the 2mins Oxygen plasma treatment the contact angle decreases from 149o to….. 0o, again while increasing the plasma treatment time, 2,3,4,5 the contact angle considerably reduced. In 6mins plasma treated surface shows the maximum reduction,

In this region two distinguish peaks are present at 2852 cm-1 and 2917 cm-1 for untreated fabrics it is due to amount of waxes (were mixtures of hydrocarbons, alcohols, esters and free acids which have long alkyl chains) left on the fabric. Chung etal 2004, H. A. Karahan etal., 2007, Hemen Davea.b etal 2014 [32,33,12] were also identified the same peaks for the untreated cotton fabrics. Non cellulosic impurities such as waxes, pectin are present in the primary wall of the surface and the secondary wall was filled with cellulose. After the 2mins plasma treatment the peaks at 2852cm-1 and 2917cm-1 were found to be very sharp intensity, it is important to note that, the waxes are more detectable, for 2mins O2 plasma (etching) treatment. Further increases the plasma treatment time 4mins, the peaks at 2852cm-1 were considerably decreased and finally disappeared for 6mins plasma treatment the peaks at 2852cm-1. As seen from Fig.4 (b) the spectra of 6mins plasma treated fabric peaks are completely disappeared which indicates the absence of waxes in the cotton fabrics. The peak at 1719.52cm-1 enhanced the absorbance of pectic polysaccharides and represented the ester groups of pectin to be closely connected with the waxes, these components located in the primary cell wall with the highest concentration at the surface. After the plasma treatment, the intensity of the peaks decreasing in the order of untreated>2mins >4mins >6mins treated fabrics. Oxygen plasma creates more free radical species such as O+, O-, O*,O2,O3 on the surface [34,35] which eliminates the non cellulosic impurities from the cotton surface. And we never obtained the nil intensity at 1719.52cm-1, which enhance the formation of carbonyl functional groups shown in fig.4(c). These species contributing to increase the amount of polar groups such as such as –OH, C=O and -COOH on the plasma