Study of Mechanical and Surface Properties on some Chemical Treated Cotton Fabric by KES-F, SEM and FTIR Analysis

Today cotton is the most used textile fiber in the world [1]. World textile fiber consumption in the end of 20th century was approximately 45 million tons. Of this total, cotton represented approximately 20 million tons [2]. India holds the largest area of 8 m ha under cotton cultivation and ranked third in world’s cotton production, next to China & USA and second largest consumer of cotton [2,3].


Introduction
Today cotton is the most used textile fiber in the world [1]. World textile fiber consumption in the end of 20 th century was approximately 45 million tons. Of this total, cotton represented approximately 20 million tons [2]. India holds the largest area of 8 m ha under cotton cultivation and ranked third in world's cotton production, next to China & USA and second largest consumer of cotton [2,3].
Unlike synthetic fibers, cotton is a natural product [4] and nonallergic since it doesn't irritate sensitive skin or cause allergies. Cotton has a high absorbency [5] rate and holds up to 27 times its own weight in water. Cotton swells in a high humidity environment, in water and in concentrated solutions of certain acids, salts and bases [6]. Chemical treatment of cotton cellulose to alter physical properties of the fibers without changing their fibrous form is a common practice in the textile industry [7].
In the application of dyestuffs to cotton, several factors are considered as of prime importance [8][9][10]. The importance of natural dyes has increased presently, with increased awareness about harmful effects of chemical dyes both in production and in its usage by human beings [11][12][13]. This dye has the rare distinction of being a dye whose use can be traced back to antiquity and which continues to be as commonly used all over the world today as it is in the ancient times [14][15][16][17].
This research work focuses on the treatment of cotton (woven and knitted) fabrics with sodium hydroxide, morpholine, and cellulase enzyme in order to improve its behavior revealed by dyeing and finishing. The cotton fabrics (treated and untreated) were dyed by some selected dyes such as annatto, onion, pomegranate, indigo, myrobalan, bar berry (natural dyes); and reactive and sulphur dyes (synthetic) respectively and subsequently finished. These fabrics were then assessed for mechanical and surface properties from KES-F, SEM analysis and FTIR studies.

Experimental Materials
Cotton (woven and knitted) fabrics with following specifications were used in this study (Table 1). Natural dyes annatto (Bixa orellana), onion (Allium cepa), pomegranate (Punica granatum), indigo (Indigofera tinctoria), myrobalan (Terminalia chebula), bar berry (Berberis vulgaris) and synthetic dyes reactive dye (reactive red HB-C.I. No. Red 24), and sulphur dye (sulphur black-C.I. No. sulphur Black 1) used were in the commercial grade. The commercial Super FX UltraSoft 2015 (Tirupur, India) was used for finishing on cotton fabrics. The other chemicals mentioned elsewhere for this study were in AR grade.
Objective assessment on dyed and finished cotton (woven and knitted) fabrics by KES-F: The mechanical and surface properties of the dyed and finished woven and knitted cotton fabrics were assessed by Kawabata evaluation system (KES-F) [23].

SEM Study on dyed and finished cotton (woven and knitted) fabrics:
Scanning electron microscope studies were carried out on dyed and finished woven and knitted cotton fabrics from 30kV scanning electron microscope JEOL (Japan) Model JSM-6360 [24].

FTIR analysis for dyed and finished cotton (woven and knitted) fabrics:
Fourier Transfer Infra-Red (FTIR) spectrophotometer (Shimadzu, Japan) was used to analyze the functional groups. The data reveal about the color absorption properties of the organic dye molecules with respect to the functional groups, aromatic and achromatic ring chains and indicated the presence of structural groups in the dye molecules [25].

Mechanical and surface properties from KES-F
The mechanical and surface properties of the dyed and finished cotton fabrics (woven & knitted) were objectively assessed by KES-F. The Primary Hand Value (PHV) (of both woven and knitted fabrics), bending length (of only woven fabric) fabrics, and crease recovery (of only woven fabric) of the dyed and finished cotton fabrics were carried out by this system and data are presented in Tables 1a,1b, 2, 3 respectively.

Primary hand value (PHV) of dyed and finished cotton (woven and knitted) fabrics:
The parameters evaluated from KES-F of dyed and finished cotton fabrics for the primary hand value of woven and knitted fabrics are given in Table 1a and 1b respectively. From these Table 1a,1b it is seen that the smoothness is observed more on the dyed and finished sodium hydroxide treated [2] cotton fabric (190% to 200%) followed by morpholine treated [3] (150% to 160%), enzyme treated [4] (130% to 140%) and untreated [1] [2][3][4]. Among the dyes, the differences in smoothness values on the cotton fabrics [UT, F1, F2/1,2,3,4] are only marginal. The stiffness of the fabrics is reduced due to the sodium hydroxide treatment, morphology treatment and enzyme treatment followed by dyeing and finishing. Compared to all treated [F1, F2/2, 3,4] and untreated [UT, and F1, F2/1] fabrics the sodium hydroxide treated cotton fabrics show reduced stiffness, this is due to the good flexibility generated by sodium hydroxide; followed by morpholine treatment, enzyme treatment and untreated dyed and finished cotton fabrics (10% to 15% in general in all these cases). The fullness is maximum (80% to 200%) on the sodium hydroxide treated cotton fabrics followed by morpholine treated, enzyme treated and untreated fabrics. In general, the primary hand value is maximum for the sodium hydroxide treated [2] fabrics followed by morpholine treated [3], enzyme treated [4]

Bending length of dyed and finished woven cotton fabric
The values of the bending length of untreated [UT, 1] and treated [sodium hydroxide, morpholine and enzyme] dyed and finished woven cotton fabrics are given in Table 2. From this table it is given as the data of the bending length both in warp and weft directions respectively of cotton fabric treated with sodium hydroxide, morpholine and enzyme followed by dyeing and finishing. It is evident from the Table 2       [UT] cotton fabric shows the maximum bending length (warp and weft) which is periodically reduced after the treatments such as enzyme, morpholine and sodium hydroxide and subsequent dyeing and finishing. These treatments reduce the bending lengths on the cotton fabrics and sodium hydroxide treatment tops the list in this reduction followed by morpholine and enzyme treatments. Dyeing and finishing also further enhances the reduction in bending lengths on all these fabrics. There are not many influences in the differences of bending length due to the change of dyes (Annatto, Onion, Pomogranate, Indigo, Myrobalan, Bar berry, Reactive Dye and Sulphur dye). The warp directions have marginally more bending length values in all these woven cotton fabrics.

Crease recovery ( o ) of dyed and finished woven cotton fabric
The data of the crease recovery both in warp and weft directions of dyed and finished woven cotton fabric treated with sodium hydroxide, morpholine and enzyme are given in Table 3. From this table, it is clearly seen that the crease recovery both in warp and weft directions of dyed [F1] and finished [F2] cotton fabric treated with sodium hydroxide [2] is minimum compared to morpholine treated [3], enzyme treated  [4] and untreated cotton fabrics [1] (5% to 20%) respectively. The undyed/unfinished untreated [UT] cotton fabric shows the maximum crease recovery (warp and weft) which is subsequently reduced after the treatments such as enzyme, morpholine and sodium hydroxide and subsequent dyeing and finishing. These treatments reduce the crease recovery on the cotton fabrics and sodium hydroxide treatment tops the list in this reduction followed by morpholine and enzyme treatments. Dyeing and finishing also further enhances the reduction in crease recovery on all these fabrics. The various dyes (Annatto, Onion, Pomogranate, Indigo, Myrobalan, Bar berry, Reactive Dye and Sulphur dye). do not give much influences in the differences of crease recovery. The weft directions have marginally more crease recovery values than those in warp directions in all these woven cotton fabrics.

SEM analysis of woven cotton fabric:
The SEM images of dyed and/or finished woven cotton fabrics (untreated, sodium hydroxide treated, morpholine treated and enzyme treated) are given in the Figure  1a, 1b, 1c, and 1d respectively. Figure 1 is the SEM image of untreated (undyed and unfinished) woven cotton fabric. As the samples were treated with different chemicals and subsequently dyed and finished, it is evident from the (Figure 1a-1d) respectively that there are some clear differences in the respective images. Accordingly, Figure 1a shows the SEM image of untreated (dyed and finished) woven cotton fabric.  Figure 2 is the SEM image of untreated (undyed and unfinished) knitted cotton fabric. As the samples were treated with different chemicals (sodium hydroxide, morpholine and enzyme) and subsequently dyed and finished, it is evident from the Figure 2a-2d respectively, that there are some clear differences in the respective images. Accordingly, Figure 2a shows the SEM image of untreated (dyed and finished) knitted cotton fabric. Figure 2b, 2c, and 2d clearly give the differences in the corresponding SEM images about the influences of the respective chemical treatments (sodium hydroxide, morpholine and enzyme) on knitted cotton fabrics. Hence, the dyed and finished sodium hydroxide treated cotton fabric (Figure 2b) gives good appearance in the SEM image followed by morpholine treated (Figure 2c) and enzyme treated (Figure 2d) respectively.

FTIR analysis of dyed woven cotton fabric
The cotton fabrics were dyed with different dyes. However as representation, barberry dye was selected for dyeing on woven cotton fabric only. The FTIR graph of barberry in the intact form is given in Figure 3. Subsequently the FTIR graph of the same dye after application on the woven cotton fabric (untreated, chemical treated and dyed) are given in the Figure 3a-3d respectively; and those for the finished fabrics (untreated, chemical treated, dyed and finished) are given in the Figure  3e-3h respectively. The color generated for barberry dye is yellow when applied on the cotton fabric. The FTIR graphs for this barberry dye (intact and dyed and finished) are shown in Figures 3-3h respectively and are analyzed as per the following data (Table 4).
From these graphs it is evident that there are groups present in the barberry dye responsible for the reaction with the cotton textile fabric.

Conclusion
The conclusions drawn from the study are summarized below: The primary hand value such as smoothness, stiffness and fullness is good in sodium hydroxide treated, morpholine treated and enzyme treated woven and knitted cotton fabrics respectively. Smoothness is observed more on the dyed and finished sodium hydroxide treated cotton fabric followed by morpholine treated; enzyme treated and untreated cotton fabrics respectively. The sodium hydroxide treated cotton fabrics have reduced stiffness due to the generation of good flexibility; followed by morpholine treatment, enzyme treatment and untreated dyed and finished cotton fabrics. The fullness is also maximum on the sodium hydroxide treated cotton fabrics followed by morpholine treated, enzyme treated and untreated fabrics. In general, the primary hand value is maximum for the sodium hydroxide treated fabrics followed by morpholine treated; enzyme treated and untreated dyed and finished woven and knitted cotton fabrics.
The bending length in both warp and weft directions of dyed and finished woven cotton fabric is good in sodium hydroxide treated one with least value followed by morpholine treated, enzyme treated and untreated fabrics respectively. The trend is common in both warp and weft directions; however the warp materials have an edge over the weft materials for the bending length.
The crease recovery in both warp and weft directions of dyed and finished woven cotton fabric treated with sodium hydroxide is minimum compared to morpholine treated, enzyme treated and untreated cotton fabric respectively revealed the good effect of sodium hydroxide. The trend is common in both warp and weft directions; however the weft materials have a little edge over the warp materials for the crease recovery.
SEM micrographs reveal that the dyed and finished sodium hydroxide treated cotton fabric gives good appearance followed by morpholine treated and enzyme treated respectively. FTIR spectra prove that there are groups present in the barberry dye responsible for the reaction with the cotton textile fabric.