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Investigation of DyeFiber Reactions in SCCO2

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Acetate, nylon, and polyester fibers colored with dispersed dyes retain their ... for dye-fiber bond formation using vinylsulfone-based dye on nylon and wool ... – PowerPoint PPT presentation

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Title: Investigation of DyeFiber Reactions in SCCO2


1
Investigation of Dye-Fiber Reactions in SC-CO2
  • NSF Green Processing Summer Research Experience
    for Undergraduates
  • Faculty Mentors Dr. David Hinks and Dr. Gerardo
    Montero
  • Graduate Student Mentor Mr. Ahmed El-Shafei
  • North Carolina State University, College of
    Textiles
  • Undergraduate Student Nneka C. Ubaka-Adams
  • Bennett College and North Carolina Agricultural
    and Technical State University

2
Abstract
  • This project is one phase of the push to use
    carbon dioxide as an environmentally safe solvent
    as opposed to the traditional solvent of choice,
    water. The piece under investigation is the
    reaction between a specific functional group and
    nylon and wool fibers at varying temperatures.
    The bond strength was measured indirectly by
    measuring the color fastness. After the dyed
    fiber was measured for color depth (by way of
    reflectance curve) it was rinsed with acetone and
    measured again. Extreme loss in color implied
    weak or incomplete bonding minor loss in color
    indicated complete or very near complete covalent
    bonding. It is expected that temperature will
    have a direct effect on the degree of complete
    covalent bonding.

3
Objectives
  • To demonstrate and quantify dye-fiber covalent
    bond formation between selected dyes and nylon,
    wool and cotton fibers in a supercritical carbon
    dioxide medium
  • To optimize reaction conditions (temperature,
    pressure and time)
  • To conduct a literature review

4
Who and What does this Research Affect?
  • Economy
  • The dyeing industry
  • The entire textile industry
  • Health
  • Factory Workers
  • water systems
  • Quality of Products
  • Textile consumers

5
Background
  • Conventional dye-fiber reactions use water as a
    transport medium, and result in
  • Low reaction efficiency due to the competing
    hydrolysis reaction with hydroxyl ions in water
    (hydrolyzed dye cannot react w/fiber)
  • Environmental problems due to residual,
    unreacted/hydrolyzed dye present in effluent
  • Replacing water with supercritical fluids (SCF)
    as a transport medium can result in
  • Eliminating toxic waste (no hydrolyzed
    by-product)
  • Lower costs for the entire dyeing process

6
Hypothesis
  • Color fastness of fibers dyed in supercritical
    fluid will be similar to fibers dyed in water
  • Color fastness of fibers dyed with disperse
    (non-reactive) dye will be extremely low
  • Dye-fiber Reaction (color fastness) will be
    directly proportional to the temperature increase

7
Chemistry of Dyes
  • Reactive dyes for cotton, rayon, silk, and wool
    form stable chemical links with textile materials
    to produce colored fabrics with excellent overall
    fastness, other dyestuffs only form loose bonds
    with fibers (VS-dye)
  • Acetate, nylon, and polyester fibers colored with
    dispersed dyes retain their color even after
    repeated exposure to sunlight and washing (ES-dye)

8
Conventional aqueous-based dye-fiber reaction
Polyamide (nylon 6.6.)
9
Dye-Fiber Reaction in SC CO2
Polyamide (nylon 6.6.)
no hydrolyzed by-products
10
Sulfonyl-azo-dyes
11
Dyeing Procedure
  • Add fiber and dye to vessel
  • Pressurize system (with CO2) up to 800 psi and
    stir at approximately 850 rpm
  • Heat to required temperature (100 -180 ºC)
  • Pressurize to 3500 psi hold for 2 hours
  • Release pressure, remove fabric

12
(1) Gas cylinder of CO2, (2) High pressure pump,
(3) Autoclave reactor vessel with stirrer, V
1000 ml, (4) Circulation pump- acquisition in
future (5) Electrical heating jacket
CO2 Dyeing System
13
High Pressure Batch Reactor
14
Testing Dye-Fiber Reaction
  • Measure color strength (K/S) of each dyed fiber
  • Wash fiber with acetone (remove surface dye)
  • Conduct soxhlet extraction using ethyl acetate
    (to remove unreacted dye)
  • Compare effect of vinylsulfone reactive group on
    dye fixation

15
Results
16
Results
17
Comparison of Dyed Fabrics
18
Initial Conclusions
  • Color depth improved with increasing temperature
  • Strong evidence for dye-fiber bond formation
    using vinylsulfone-based dye on nylon and wool
  • ES-dyeing on wool fibers showed extremely low
    color yields after extraction (no reaction)
  • 94 fixation at 180 oC/ 3500 psi on wool

19
Future Work
  • Test time as a factor- 60-90 min
  • Test with cotton fiber
  • Test with commercial dye
  • Test with different amount of dye- i.e. 0.5
    o.w.f, 1.5 o.w.f.
  • Extract nylon fibers with a better solvent

20
Acknowledgements
  • NSF Green Processing REU
  • North Carolina State University, College of
    Textiles
  • Dr. Christine Grant
  • Dr. Steve Peretti
  • Dr. David Hinks
  • Dr. Gerardo Montero
  • Mr. Ahmed El-Shafei
  • Mrs. Kirsten Reberg-Horton
  • Mr. Lynell Williamson
  • Jacob Hooker
  • Mr. Jeff Krauss
  • Mr. Chris Cazzola

21
Acknowledgements
  • This research was conducted with the support of
    the NSF
  • Green Processing Undergraduate Research Program
    with a
  • grant from the National Science Foundation, Award
  • Number, EEC-9912339.
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