The main aim of this present study is to improve the dyeability of polyester and polyester blends. The fabrics were treated with varying concentration of micro crystalline cellulose powder with two binder types viz texacryl binder SLN and acrylic binders using coating method. The treated fabrics were measured for their absorbency, wicking, air-permeability, dyeability and flexural rigidity. The absorbency and wicking of treated fabrics were found to be improved. Color strength increased drastically after treating with MCC particles compared with untreated fabrics. Air-permeability and tearing strength of both the treated fabrics observed to be reduced with increase in MCC concentration along with the binder. FTIR spectra studies also been confirmedthe presence of hydroxyl groups.
Keywords: 100% Polyester fabric, P/C Blended fabric, Micro-crystalline cellulose powder, Contact angle, K/S, FTIR.
Polyester consists of long polymer chain of at least 85% of esters and dihydric alcohol and a terepthalic acid. It is nothing but fibres linking of several esters groups that are presented. These esters are formed by reaction between alcohol and carboxylic acid, which forms the backbone of polymer in the polyester. The polyester is extremely strong, hydrophobic in nature and can be dry easily due to less moisture regain. The surface modification of polyester can be carried out to customize the moisture regain and to overcome the draw backs such as static electricity generation and soiling problem. The moisture regain of the polyester is 0.4% at RH of 65%±2, and after surface modification there is scope to increase the moisture regain. It is necessary that the surface modification to be done to improve the hydrophilic property of the polyester .
Surface modification of polyester can be done by several methods like by using polyvinyl alcohol in alkaline medium, low temperature plasma treatment, ammonia dielectric barrier discharge, and also by using micro crystalline cellulose powder. Because of its hydrophobic nature the polyester fabric shows the contact angle of water droplet is more than 90°. PVA treated polyester fabrics shows increase of moisture content will decrease the static water contact angle of about 67.31° due to the formation of hydrophilic surface . Low temperature plasma treatment is having significant improvement in wettability of cotton and polyester fabrics also the surface resistivity is reduced which intern shows the conductivity of fibers. Modification of polyester and polyamide fabric by different in situ plasma polymerization methods were carried out by T.Oktem, which shows the improvement in wettability, soil resistance and dyeability . Polyester treated with different sources of lipase enzyme at 0.04 mg/ml, 30 min reaction time at 25°c and pH-8. The results shown that, there is a significant improvement in the hydrophilicity and dyeability of polyester fabric. Investigations were carried out on surface modification of polyester with PVA at 6% concentration of NaOH shows significant improvement in air-permeability and wicking height. Generally, Micro crystalline cellulose powder is extracted from the cotton waste, mango kernel and wood pulp etc. Moisture and ash content of received sample correspond to preparation of MCC from cotton. MCC sample is high crystalline. Surface modification of polyester and P/C blended fabrics carried out by using micro crystalline cellulose powder by M. El Messiry and it was concluded that the spraying MCC particles on to the fabric surface directly improves the wettability and moisture management properties of treated fabrics .
Further, there is a need for in depth analysis of micro crystalline cellulose particles on properties like dyeability, air permeability, tearing strength and stiffness of treated polyester fabric. In the present study, the surface modification of polyester is carried out with micro crystalline cellulose powder by using Texacryl binder SLN and acrylic binders. The treated fabrics were evaluated for their comfort, fabric handle properties and dye ability.
Materials and methodology
Polyester and polyester/cotton blended fabrics were selected for the study and the specification are shown in the table 1. Microcrystalline cellulose particles, Texacryl binder SLN and acrylic binders were procured from the local market for the study.
The surface modification is carried out using MCC particles on to the pre-treated polyester and P/C blended fabric by coating method using Texacryl binder SLN and acrylic binders with variable concentrations as per the table 2. The synthetic thickener is used to maintain the viscosity of MCC paste. Table 3 shows the treatment combinations with which the fabrics were treated.
Coating paste is prepared by using MCC particles of required concentrations with binder, thickener and water with stirring to maintain the viscosity and homogeneous mixing. After the preparation of the paste it was applied on to the fabric by means of squeezer at room temperature and the coated fabrics were allowed to dry at 80°c for 20 min and then subjected to cure at 150°c for 10min. The cured samples were taken for washing and drying.
Results & discussion
The properties of untreated polyester and polyester/cotton blended fabrics are shown in table 4. The polyester and P/C blended fabrics were treated with various combinations as per the treatment combinations given in table 3. The results of the treated fabrics were given in table 5.
Effect of % MCC concentration on air-permeability
The effect of MCC concentration of air-permeability of both polyester and P/C blended fabrics treated with SLN and acrylic binders were studied. Fig 1. shows the air-permeability of untreated and treated polyester fabrics measured using standard method ASTM D 737-96. It is evident from the fig 1 that, the air-permeability of polyester fabrics treated with SLN and acrylic binders of increasing MCC concentrations leads to decrease in air-permeability compared with untreated fabrics. This may be due to fact that the treatment with MCC particles along with binders reduces the porosity of treated fabrics.
MCC with SLN binder treated fabrics showed reduced air-permeability than acrylic treated fabrics. Similar trend is followed for P/C blended fabrics which is shown in fig 2.
Effect of % MCC concentration on absorbency
The effect of %MCC concentration on absorbency time of treated polyester and P/C blended fabrics were shown in fig 3 and 4. It shows that, water droplet takes around 3sec time to completely absorb by the treated fabrics compared with untreated fabrics of 20 to 25 sec. The presence of hydroxyl groups on the surface of treated fabrics which makes them hydrophilic.
Effect of % MCC concentration on wicking behaviour
The wicking behaviour of untreated and treated fabrics was shown in fig 5 and 6. It is observed that the wicking height of both warp and weft has been increased in both the fabrics after treatment of MCC along with binders. Structural changes in the treated polyester fabrics are responsible for increased vertical wicking height by increasing the MCC concentration upto 6%. Further increase in concentration of MCC particles reduces the wicking height.
In case of P/C blended fabrics the vertical wicking height is significantly increasing by increasing MCC concentration in both SLN and acrylic binders. The treatment induces structural changes in the P/C blended fabric in which more number of hydroxyl groups was present and confirmed by FTIR results.
Effect of % MCC concentration on tear strength
The evaluation of tearing strength is carried out using the standard method of ASTM D 1424-09. Tearing strength of polyester and P/C blends of untreated and treated fabrics are shown in fig 7 and 8. It is evident from the figures that, the tearing strength of both the fabrics after treatment with MCC and binders is decreased. Reduction in tearing strength may be because of more bonding between MCC and binder onto the fabric restricting the thread movement.
Effect of % MCC concentration on flexural rigidity
Flexural rigidity of treated and untreated fabrics was shown in the fig 9 and 10. The stiffness of polyester and P/C blends were increased after the treatment of MCC with binders. The treated fabrics with increase in MCC concentration up to 6% with both the binders, there is an increase in the pattern of stiffness. Further increase in the concentration of MCC the stiffness is reduced for both polyester and P/C blends. It is due to the treatment makes the fabric stiffer.
Effect of % MCC concentration on colour strength
Colour strength measurements are carried out using Spectrophotometer SS5100H as per the standard method of AATCC 6(2003), RA36. The treated and untreated polyester fabrics were dyed with basic red of common 3% shade and results shown in table 6. It was found that the color strength is less in untreated polyester fabric i.e. 6.77 when compared with MCC along with binder treated fabrics of 79.08. Fig 11 shows the relation between K/S and MCC concentration and found that there is a significant effect of MCC concentration and binder on colour strength.
The treated and untreated P/C blended fabrics were dyed with basic red of common 3% shade and results shown in table 7. Compared with untreated P/C blended fabrics the colour strength of treated P/C blended fabrics was improved drastically from 26.12 to 115.52. It may be due to the bonding between MCC particles, binder on the fabric which introduces more hydrophilic cites in the fabric structure. Fig 12 shows the trend of K/S of treated P/C blended fabrics.
Effect of % MCC treated on contact angle
Contact angle measurements were carried out for both untreated and treated fabrics by using Holmarc opto contact angle meter. The water droplet contact angle of untreated fabric fig 13 (a) and treated fabrics fig 13 (b) shows that the contact angle is high in case of untreated fabrics compared with treated fabrics. This is may be because of increase in hydrophilic sites in the fabric structure after treatment with MCC particles.
The FTIR spectra of intact & treated polyester fabrics were shown in figures 14 – 16. The peaks found in the region from 500 cm-1 to 1700 cm-1 shows the original signals, such as characteristic spectra of stretching vibration band of C=O at 1709.265cm-1 and C-O-C stretching vibration band at 1093.001cm-1 and 1239.944 cm-1. All these peaks confirms the presence of ester groups . The spectra of polyester treated fabrics with MCC particles along with SLN, acrylic binders in the fig 15, 16 confirms the presence of O-H groups in the wave number 3420.7643 cm-1 and 3405.855 cm-1. O-H groups responsible for improving absorbency and dye ability of treated fabrics. Stretching band of C=O & C=N at 2095cm-1 to 1947cm-1 confirms the presence of binder holding the MCC particles on fabric surface.
FTIR spectra of untreated and treated P/C blended fabrics were shown in the figures 17-19. The stretching band of ester and hydroxyl groups at 1709.421cm-1, 3420 cm-1 confirms the original signals of both polyester and cotton respectively. In the treated fabrics it confirms the broad stretching band of N-H, C-H at 2800 cm-1 to 3000 cm-1 wavenumber.
The treatment with micro crystalline cellulose powder along with binders significantly increased the wetting behaviour of treated fabrics measured in terms of absorbency and wicking. The water contact angle of MCC treated fabrics found to be much less than the untreated fabrics confirm the hydrophilic characteristic. Air permeability and tearing strength of treated fabrics were found to be reduced. Flexural rigidity of treated fabrics increased after treatment with MCC and binders. Increasing in MCC concentration significantly improved the dyeability of treated fabrics. The presence of binder and O-H groups are confirmed by FTIR studies.
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B. Venkatesh, Govardhana Rao Chilukoti, M. Siva Jagadish Kumar, Md. Vaseem Chavhan, Chetan K. L
Vignan's Foundation for Science, Technology & Research, Vadlamudi.