Natural dyes are derived from natural resources based upon their source of origin. These are broadly classified as plant, animal, mineral, and microbial dyes. As plants are the major sources of natural dyes interest in natural dyes grew. Information about natural dyeing was collected from the old literature and traditional dyeing practices in different regions were documented, compiled by various researchers. Later information on various dye-yielding plants, methods to grow them, harvesting dye parts, methods to dye wool and silk with natural dye, and color shades developed were also collected. Historically, plants have been used for the extraction of a majority of natural dyes. Many dyes are available from tree waste or can be easily grown in market gardens. The famous natural blue dye, indigo is obtained from the leaves of the plant Indigofera tinctoria. Various plant parts including roots, leaves, twigs, stems, heartwood, bark, wood shavings, flowers, fruits, rinds, hulls, husks, and the like serve as natural dye sources. Some plant-derived dyes have other applications as they can be used as food ingredients and medicines in traditional medicine systems.
Natural dyes can produce special aesthetic qualities, when combined with the ethical significance of a product that is environmentally friendly, giving added value to textile production as craftwork. But this could also be in response to the negative impact created by synthetic dye manufacturing is having on the environment and human health. This is caused during dye synthesis, the release of undesirable/hazardous and toxic chemicals in nature and the effect synthetic dyes can have upon human health, as irritants/sensitizers synthetic dyes are often the cause of allergic reactions. In areas where synthetic dyes, mordants (fixatives), and other additives are imported and therefore relatively expensive, natural dyes can offer an attractive alternative. Recently there has been a revival of the growing interest in the application of natural dyes on natural fibers due to worldwide environmental consciousness. Therefore view in order to obtain newer shades with acceptable color fastness behavior and reproducible color yield, appropriate scientific techniques or procedures need to be derived from scientific studies on dyeing methods, dyeing process variables, dyeing kinetics, and compatibility of selective natural dyes.
In the world today, the position of natural dyes and colorants, ‘nature’s colors’ are at crossroads. They will either vanish and with them, the ancient knowledge and skill that has advanced with their use over centuries and across civilizations or they will evolve to create a new form of coloration and with this be applied to new environmental/sustainable applications and possibility be recognized for the health/healing aspects they can provide. Currently, there is increasing interest in natural dyes and colorants, as interest grows within the Industrialized Nations in natural (Green) products and sustainable ways of living. Hence this leads to a renewed interest in natural dyes which has increased their commercial availability. Further growing interested in natural dye application is based on, not just the system of national heritage protection and multifunctional properties, but with interest found in the fact that a garment-dyed by natural dyes holds an alternative economical, touristic as well as humanly, ecological significance.
This work is concerned with the extraction of dye from Eucalyptus bark and its application on selected cotton knit materials in an endeavor to study the application conditions and antibacterial activity.
SELECTION OF FABRIC
Fabrics made from cotton yarn have immense “Breathable” properties due to their high air permeability structure. Cotton is a natural fiber that possesses most of the distinctive comfort properties compared to other cellulosic fibers. Cotton fabric is breathable and transmits moisture away from the body and is absorbent that removes liquid from the skin. Because cotton is a natural product designed and manufactured into clothing, due to its many advantages, such as its ability to control moisture, insulate, provide comfort, hypoallergenic, weatherproof, and is a durable fabric. Keeping the above points in mind the investigator selected cotton material for the study.
SELECTION OF FABRIC CONSTRUCTION
Knitting is a process of fabric forming by interloping the loops of yarns. When one loop is drawn through another, loops are formed in horizontal or vertical directions. Due to the interesting looping structure of the yarn, the investigator selected the knitted fabrics, pique (PO) (2×2), and interlock (IO) (1×1) knit for the study.
SELECTION OF DYE
Natural dyes are better than synthetic dyes. Natural dyes are better products, as they do not contain chemicals harmful to health and the environment. Naturally dyed products are healthier and more reliable than chemical synthetic dyed products. Hence the investigator planned to select natural dye for dyeing the cotton knit Pique (PO) and Interlock (IO) fabrics for the study.
SELECTION OF NATURAL DYE
Eucalyptus bark is one of the most important sources of natural dye yielding several yellowish to brown colorants. The eucalyptus bark contains a high amount of tannins, phenols, and flavonoids. The tannins provide an auxochromic group to bind the coloring component to synthetic and natural fabrics. The eucalyptus bark was collected from trees, grown at Chikkanna Government Arts College, Tirupur. The shed eucalyptus bark was collected by the investigator. After the collection of barks, it was washed thoroughly with water to remove impurities present on the surface of the bark and dried. The dried eucalyptus barks were powdered.
SELECTION OF MORDANT
Terminalia chebula is a flowering evergreen tree native to Asia. The fruits of this tree are extensively used in traditional medicine systems. The pericarp of mature fruits of the Harad tree constitutes the drug. They are rich in hydrolyzable tannins (pyrogallic) and very astringent and with good lightfastness. The natural dyes have limited substantively for the fiber, so natural dyes require the use of mordants, which enhances the fixation of the natural colorant on the fiber by the formation of the complex with the dye. Myrobalan is both tannin and a dye, giving warm soft gold yellow color. Myrobalan works well for over-dyeing as well as pre dye. Myrobalan seed is powdered for the study and is used as a mordant.
PREPARATION OF NATURAL DYE
Dried powdered Eucalyptus bark, was used for the extraction of natural dye. For dyeing the Pique (PO), Interlock (IO) knit cotton fabric required grams of eucalyptus bark powder was taken based on the weight of the Pique (PO) and Interlock (IO) knit materials. The M:L ratio taken for extraction was 1:40. The dye solution was boiled at a temperature of 1000C for one and a half hours. The eucalyptus bark dye solution was filtered using a muslin material to remove fragments of bark particles if present. The extracted natural viscose dye of eucalyptus bark was kept ready for further process.
PRE-TREATMENT OF COTTON KNITTED MATERIALS
Scouring was given as pre-treatment to cotton knitted Pique (PO) and Interlock (IO) materials. The cotton knitted Pique (PO) and Interlock (IO) materials were steeped into warm water with 10g of ariel soap powder for half an hour. After the desired time, the material was taken out and excess liquor was drained out. Then the knit materials were rinsed in cold water, dried in shade. The knitted cotton Pique (PO) and Interlock (IO) materials were ironed without any wrinkles for the dyeing process.
APPLICATION OF NATURAL DYE
The filtered viscose-natural dye extracted from Eucalyptus bark was taken in an M:L ratio of 1:20 (6%) for both Pique (PO) and Interlock (IO) knit materials. To this natural dye liquor, required grams of myrobalan mordant powder (3%) was added to the dye bath for simultaneous mordanting and stirred continuously without lumps. The cotton knitted Pique (PO) and Interlock (IO) materials were pre-soaked in water for god absorbency. The extra water was squeezed out. The Pique (PO) and Interlock (IO) knit materials were then steeped into the eucalyptus bark dye bath for dyeing. The dye bath was boiled for half an hour at 50o C - 600 C. After the required time, the Pique (PD) and Interlock (ID) knit materials were taken, rinsed in cold water, and dried in shade.
The original Pique (PO) and Interlock (IO) knitted and dyed Pique (PD) and Interlock (ID) knitted materials were subjected to fabric tests such as fabric weight (ASTM D3776), Bursting strength (ISO 13938-2-2010), Drape (IHTM 21) and Pilling (ISO12945-2-2002). The color fastness tests are also analyzed in dyed pique (PD) and interlock (ID) cotton knit materials for sunlight (ISO 105 B02), washing (ISO 105 C06), perspiration (ISO 105 E04), and rubbing (ISO-105-X12). The dyed knit fabrics were subjected to the antibacterial test.
The test fabrics PO (original-1), IO (original-2), PD (dyed-1), and ID(dyed-2) were analyzed for antibacterial testing using the standard EN ISO-20645 test method. An antibacterial test was done to dye Pique PD and Interlock ID materials. Antibacterial qualitative evaluation was carried out. Test organism cultures micro-organisms used for the study are Escherichia coli (gram-negative) bacteria and S. aureus (gram-positive) bacteria. E. coli (plate 5) was selected for its resistance to common antimicrobial agents and S. Aureus (plate 6) is the major cause for cross-infection and it is the most frequently evaluated species. Using the parallel streak method, antibacterial activity against gram-positive and gram-negative bacteria was tested using dyed Pique (PD), Interlock (ID) against original Pique (PO) Interlock (IO) knit samples. Test specimens of PO (original-1), IO (original-2), PD (dyed-1) and ID (dyed-2) were cut into pieces (20mm in diameter). Sterile AATCC bacteriostasis agar plates were prepared. Using a sterile 4mm inoculating loop, one loop full of bacterial culture was transferred by swabbing all around the surface of the agar plate and also covering the central area of the Petri dish. The plates were incubated at 37°C for 24 hours. The inoculated plates were examined for the interruption of growth along with the swabs of inoculum beneath the fabric and for a clear zone of inhibition beyond the fabric edge. The zone of inhibition around the test specimen is calculated in mm. The result obtained from the antibacterial test is recorded under results and discussion in Table I.
CONSTRUCTION OF APPAREL
The original cotton pique (PO and PD) and interlock (IO and ID) knit materials was then converted to a T-Shirt for four years kid using sunburst tie and dye technique
ANALYSIS OF FABRIC WEIGHT
The average result for fabric weight of PO, IO, PD and ID pique and interlock cotton knit materials is shown in Figure 1.When compared within original and dyed pique and interlock knit materials from fig. 1, PD shows an increase in fabric weight when compared to PO. Similarly, ID also shows an increase in fabric weight than IO. When compared between original pique and interlock knit materials, IO shows increase in fabric weight when compared to PO. When compared between dyed pique and interlock knit materials ID also shows an increase in fabric weight than PD. When compared among the four PO, IO, PD and ID cotton knit materials, ID showed increase in fabric weight.
ANALYSIS OF BURSTING STRENGTH
The average result for bursting strength of PO, IO, PD and ID pique and interlock cotton knit materials is shown in Figure 2. When compared within original and dyed pique and interlock knit materials, from fig. 2, PO shows higher bursting strength than PD. But ID reveled higher bursting strength than IO. When compared between original pique and interlock knit materials, PO showed higher bursting strength than IO. Whereas when compared between dyed pique and interlock knit materials, ID showed higher bursting strength than PD. When compared among the four PO, IO, PD and ID cotton knit materials, ID showed best bursting strength.
ANALYSIS OF DRAPE
The drapability grade result obtained from pique and interlocks knit materials, reveals that when compared within and between PO, IO, PD and ID shows similar satisfactory draping quality.
ANALYSIS OF PILLING
The pilling grade results obtained from pique and interlock knit materials from reveals that when compared within original and dyed pique knit materials PD is satisfactory in pilling nature than PO. When compared within original and dyed interlock knit materials, both IO and ID did not reveal good pilling nature. When compared between original and dyed pique and interlock knit materials PD showed satisfactory in pilling. When compared among all the four cotton knit materials PD revealed satisfactory pilling result.
ANALYSIS OF COLOUR FASTNESS TESTS
The colour fastness tests are analyzed in dyed pique (PD) and interlock (ID) cotton knit materials for sunlight, washing, perspiration and rubbing.
ANALYSIS OF COLOUR FASTNESS TO SUNLIGHT
The result obtained for colour fastness to sunlight shows that the colour change when analyzed for the dyed cotton knit pique (PD) and interlock (ID) materials when tested against sunlight showed slight change to (equal) no change.
ANALYSIS OF COLOUR FASTNESS TO WASHING
The result shows that there is light colour change in the sample. When checked for staining the dyed cotton knit pique and interlock materials showed no colour change and staining.
ANALYSIS OF COLOUR FASTNESS TO PERSPIRATION
Perspiration is carried both in acid and alkaline medium. From, the result obtained for colour change and staining for acid perspiration samples revels that there is satisfactory results (no colour change and staining) for both PD and ID knit materials. In Alkaline medium, PD and ID knit samples showed no colour change but slight colour staining.
ANALYSIS OF COLOUR FASTNESS TO RUBBING
Rubbing is carried both in dry and wet medium. From, the results for both dry and wet rubbing for PD and ID knit samples showed satisfactory - no colour change and staining.
ANALYSIS OF ANTI BACTERIAL TEST
The result obtained for anti bacterial test for PO, IO, PD and ID cotton knit materials is recorded in Table I
It is noted from table I, Antibacterial of the eucalyptus bark dye extract, original and dyed materials was tested against gram negative (Escherichia coli) and gram positive (Staphylococcus aureus) bacterias. PD and ID indicates that the eucalyptus bark dye extract resulted in a zone of inhibition of 26 mm in PD and 28 mm in ID for E.coli and 27 mm in both PD and ID for staphylococcus aureus. The result clearly shows the eucalyptus bark dyed samples inhibits both bacteria which proves that antimicrobial agent was successfully coated on pique and interlock cotton knit materials. The PO and IO did not inhibit any of the bacterias. The presence of tannins and flavonoids in eucalyptus bark, both of which exhibit antimicrobial activity, may have been responsible for the higher antibacterial activity of the eucalyptus bark dye extract. Hence, it can be concluded that the eucalyptus dyed samples have good antibacterial activity against test organisms Escherichia coli and Staphylococcus aureus.
Consumers benefit when they are not exposed to environmental toxins, such as heavy metals, pesticides and other chemicals that are embedded in the fibers of conventionally produced textiles. It can be concluded from the present study that the eucalyptus dye has good antibacterial activity. Hence, the eucalyptus dye material and apparels can be used for green apparels. There is lack of awareness among people about eco fashion as the low efforts among retailers or manufacturers to promote green goods and benefits thereof, failure of eco- labeling scheme in India, limited information on production processes among consumers, availability of narrow range of green products in the market. Therefore, it is necessary to create more awareness among consumers regarding eco fashion. More brands need to launch into manufacturing of green fashion to cater to the demands of customers and for the benefit of both humans and environment in the real scenario. So in near future if awareness is created among consumers then more natural dyed material and apparels will be focused in the market.
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