Lecture 9 quality evaluation
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The document discusses various methods for evaluating the quality of bleached, dyed and printed textiles, including: 1) Identification tests for different fibers like burning tests and solubility tests. 2) Methods to evaluate desizing, scouring, bleaching, dyeing and printing efficiency. 3) Tests for fastness properties like wash fastness, light fastness and rubbing fastness. 4) Requirements for laboratory facilities and equipment to conduct various tests. 5) Methods to estimate banned amines and heavy metals and their impact on human health.
Lecture 9 quality evaluation
- 1. Quality evaluation of bleached, dyed and printed textiles R.B.CHAVAN Department of Textile Technology Indian Institute of Technology Hauz-Khas, New Delhi 110016 E-mail: rbchavan@hotmail.com
- 2. Identification of fibres Burning test Burn, no melting, black char Acrylic Does not burn, melt, white hard bid Polyester Does not burn, melt, white hard bid Nylon Does not burn, rotten smell Silk Does not burn, smell burning hair, balck char Wool Burn with continuous flame, smell burning paper Cotton Burning behaviour Fibre
- 3. Solubility test Dimethyl formamide (DMF) Acrylic Formic acid Nylon Ortho chloro phenol (OCP) Polyester Saturated zinc chloride Silk 5% NaOH, boil Wool Cuprammonium hydroxide, cadoxene Cotton Solvent Fibre
- 4. Desizing enzyme activity 1. Rate of disappearance of blue colour of stach iodide solution 2. Rate of decrease in viscosity of starch solution Desizing efficiency Qualitatative Staining with starch iodide solution of desized fabric Quantitative Determination of weight of sized and desized fabric of same dimensions Quantitative estimation of residual starch on desized fabric.
- 5. Scouring efficiency Time required for absorption of a drop of water on scoured fabric ( 3 seconds) Sinking test (Yarn, Fabric) Bleaching efficiency Whiteness of bleached fabric (% reflection of light 70%) Fibre degradation during scouring and bleaching Carboxyl group estimation (Methylene Blue absorption) Estimation of Aldehyde groups (Copper Number) Loss in strength of fabric (Tensile strength)
- 6. Dyeing and printing Colour strength of commercial dye Comparison of dyeing of standard dye sample and test sample Measurement of optical density of same concentration of standard and test dye sample Fastness properties Wash fastness Light fastness Rubbing fastness (Crock fastness) Perspiration fastness Fastness to chlorine
- 7. Fastness property evaluation Grey scale Grey scale for colour change Grey scale for staining Fastness grades 1-5 for all except light fastness Grade 1 Poor Grade 5 Best Light fastness grade 1-8 Grade 1 poor, Grade 8 best Blue wool standards from grade 1-8 essential for exposure of samples to light
- 8. Laboratory facilities Spectrophotometer Digital balance with accuracy upto three decimals Fade-o-meter for light fastness Landero-meter for wash fastness Crock meter for rubbing fastness Perspiro-meter for perspiration fasness Tesnsile strength tester Abrasion tester Stiffness tester Crease recovery angle tester Pilling tester Abrasion tester
- 9. Environment related parameters Estimation of banned amine on dyed sample Principle Reduction of dye from dyed or printed sample with sodiun hydrosulphite and casutic soda under standard conditions. Estimation of liberated amine using HPLC Or GC-mass spectrometer Comparison of peaks with standard amines
- 10. List of banned amines Amine 1-4 Carcinogenic to human Amine 5-20 Carcinogenic to animals
- 11. Mechanism of dye degradation in human body
- 12. Metal Estimation Cr, Cu, Hg etc Instrument used Atomic abasorption spectrometer