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Ultrasonic waves dyeing

dyeing of fabrics using ultra sonic waves

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Ultrasonic waves dyeing

  2. 2. ULTRASOUND • The possibility of dyeing textile using ultrasound was started in 1941 • Ultrasound is an oscillating sound pressure wave with a frequency greater than the upper limit of the human hearing range • ultrasonic frequencies lie between 20 kHz and 500 MHz
  3. 3. BUBBLING PHENOMENON •Ultrasound energy is sound waves with frequencies above 20,000 oscillations per second. •In liquid, these high-frequency waves cause the formation of microscopic bubbles, or cavitations. •They also cause insignificant heating of the liquid. Ultrasound causes cavitational bubbles to form in liquid.
  4. 4. •When the bubbles collapse, they generate tiny but powerful shock waves •There is a compression or rarefaction during each cycle of wave. •When ultrasonic waves are absorbed in liquid system,the phenomenon of cavitations takes place, which is the alternate wave formation, oscillation and collapse of tiny bubbles or cavities.
  5. 5. •During the rarefaction of the portion of the wave cycle, dissolved gas molecules act as nuclei for the formation of cavities, which may expand relatively slowly up to a diameter as much as 0.1 cm. and then quickly collapse during the compression portion of the cycle
  6. 6. GENERATION OF ULTRASONIC WAVES •The ultrasonic waves can be generated by a variety of ways. Most generally known are the different configurations of whistles, hooters and sirens as well as piezo- electric and magnatostrictive transducers..
  7. 7. •The working mechanism of sirens and whistles allows an optimal transfer of the ultrasonic sound to the ambient air •In the case of magnatostrictive and or piezo-electric transducers of ultrasonic waves, the generators as such will only produce low oscillation amplitudes, which are difficult to transfer to gases.
  8. 8. •The occurrence of cavities depends upon several factors such as the frequency and intensity of waves, temperature and vapour pressure of liquids.
  9. 9. EQUIPMENTS FOR ULTRASONICS • Generator and converter or cleaning bath are the two main components of ultrasound equipment. • Generator converts 50 to 60 Hz alternate current to electrical energy of high frequency.
  10. 10. •This electrical energy is fed to the transducer where it is transformed to mechanical vibration. •The transducer system vibrates longitudinally transmitting waves into liquid medium. As these waves propagate cavitation occurs.
  11. 11. •Prototype dyeing machine was designed for continuous dyeing of yarn and fabric. •The system mainly consists of the ultrasonic tank, transport system and microprocessor, which is used to monitor the process. •Ultrasonic tank is of 92 x 60 cm dimensions and capacity up to 200 litres. Temperature can be varied up to 100°C by thermostatic control.
  12. 12. DYEING •The use of ultrasound in the dyeing of textile can be explained as: when ultrasound waves are absorbed in the liquid system the phenomenon of cavitations takes place. Cavitations can liberate entrapped gases from liquid or porous materials like textiles, dyebath etc. The influence of ultrasound on dyeing is explained tohave three-way effects:
  13. 13. •The influence of ultrasound on dyeing is explained tohave three-way effects: • (I) Dispersion: Breaking up of micelles and high molecular weight aggregatesin to uniform dispersion in the dye bath. • (ll) Degassing: Expulsion ( dissolved or entrapped gases or air moleculesfrom fiber capillaries and
  14. 14. interstices at the cross over points of fiber in toliquid and removed cavitations. • (Ill) Diffusion: Accelerating the rate of diffusion of dye inside the fiber by piercing the insulating layer covering the fiber and accelerating the interaction between dye and fiber.
  15. 15. ADVANTAGES• Energy savings, • Process enhancement • Reduced processing times, • Maintains or improves product quality • Reduces the use of auxiliary chemicals. • Ultrasound is more beneficial to the application of water insoluble dyes to the hydrophobic fibres • Low temperature processes • Lesser load to the effluent
  16. 16. DISADVANTAGES •Producing high intensity, uniform ultrasound in a large vessel is difficult
  17. 17. THANK YOU