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Bicomponent Fibers
Brought to you by-
Bicomponent Fibers
• Bicomponent fibers are filaments made up of two different
polymers that are extruded from the same sp...
Why Bicomponent Fibers?
• The conventional fibers may not have all the desirable
properties. By the use of bicomponent fib...
Types of Bicomponent Fibers:
• These fibers can be produced in many geometrical
arrangements. On the basis of cross sectio...
Typical
Applications:
• The bicomponent
fibers can have a
range of
functionality and
applications for
different end-
uses ...
Spinning of Bicomponent Fibers
For proper spinning of two components it is required that:
• Viscosities of the two polymer...
• The first commercial bicomponent fiber was introduced by
DuPont in the mid 1960s. This was a side-by-side hosiery yarn
c...
Figure 1. Photograph of a
Bicomponent Spinning Machine
Figure 2. Sketch showing parts of
Bicomponent Spinning Machine
Core-Sheath Bicomponent Fibers
• In core sheath structure, one of the components called
core is fully surrounded by the se...
• Concentricity/eccentricity of the core can be tuned
according to end application. If the product strength is the
major c...
Applications of Core-Sheath Bicomponent
Fibers
• Core imparts strength (reinforcing material) and sheath has dye
ability, ...
Figure 4. Technique for Core-Sheath Fiber formation
Core-Sheath Bicomponent Fibers
• In case of concentric fibers the core polymer is in the center of the
spinning orifice ou...
Side by Side Bicomponent Fibers
• These fibers contain two components lying side-by-side.
Both components are divided alon...
Figure 5. Schematic showing melt
spinning of side by side bicomponent
fibers
Multi layer, fine or microfibers
• After the commercialization of self-crimping bicomponent
fibers in 1960’s, attempts wer...
Figure 6. Evolution of Microfibers
• Besides direct spinning most other techniques for the
production of microfibers involve the spinning of a
multicomponent...
Figure 7. Microfiber produced by
separation/splitting
Segmented Pie
• These are made from alternate wedges made from two
different polymers. The number of wedges is around 16 t...
Figure 8. Segmented pie bicomponent fibers
Figure 9. Schematic showing melt spinning
of segmented pie structured fibers
• PET and Nylon
bicomponent fiber is
split by soaking in a
hot caustic solution
of 5-10% NaOH.
PET and Nylon are
separated...
• Sanding and
brushing can also
be used for splitting
fibers. But it works
only with fibers that
are easily splitable
such...
Islands in the sea
• These are also called as matrix-fibril fibers. In cross
section there are areas of a polymer (island)...
Bicomponent
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Bicomponent

Bicomponent fibers are filaments made up of two different polymers that are extruded from the same spinneret with both polymers contained within the same filament but separated by a fine plane. The two polymers differ in chemical nature or physical properties such as molecular weight

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Bicomponent

  1. 1. Bicomponent Fibers Brought to you by-
  2. 2. Bicomponent Fibers • Bicomponent fibers are filaments made up of two different polymers that are extruded from the same spinneret with both polymers contained within the same filament but separated by a fine plane. The two polymers differ in chemical nature or physical properties such as molecular weight.
  3. 3. Why Bicomponent Fibers? • The conventional fibers may not have all the desirable properties. By the use of bicomponent fibers, the functional properties of both the components can be exploited in one filament. Further, the fibers can be produced in any cross-sectional shape or geometry. The properties of these bicomponent fibers are governed by : • Nature /properties of two materials • Their arrangement in the fiber • Relative proportion of the two • Thickness of the fiber
  4. 4. Types of Bicomponent Fibers: • These fibers can be produced in many geometrical arrangements. On the basis of cross section, these can be classified as • In addition to these main classes, a wide variety of bicomponent fibers having different cross-sectional geometries can be produced.
  5. 5. Typical Applications: • The bicomponent fibers can have a range of functionality and applications for different end- uses as given in the table. Functionality Some End-use Applications Antistatic Lining clothes, work wear, knitted fabrics, underwear Liquid absorbing Sports wear, felt pens, liquid absorbers, underwear Self-crimping Stockings, beddings, heat insulators, knitted fabrics, carpets Thermal Bonding Nonwoven fabrics, beddings, mattresses, printing screens, cushions, Electro- conductive Carpets, seating, work wear, knitted fabrics Light-conductive Communication, decoration, telephone Other Enhancement of properties such as - mechanical properties, aesthetics, dyeability, water repellency, flame retardancy
  6. 6. Spinning of Bicomponent Fibers For proper spinning of two components it is required that: • Viscosities of the two polymer fluids are comparable. The viscosity should be high enough to prevent turbulence after the spinneret. • Drawability of the two polymers should also be comparable, otherwise splitting may occur. • Compatibility of both components with the spinning method that is melt spinning or solution spinning is also important.
  7. 7. • The first commercial bicomponent fiber was introduced by DuPont in the mid 1960s. This was a side-by-side hosiery yarn called "cantrese" and was made from two nylon polymers, which, on retraction, formed a highly coiled elastic fiber. In the 1970s, various bicomponent fibers began to be made in Asia, notably in Japan. Very complex and expensive spin packs were used for manufacturing. These techniques were found to be technically unsatisfactory and excessively expensive. Later in 1989, a novel approach was developed using thin flat plates with holes and grooves to route the polymers. This process was very flexible and quite price effective. • These are melt-spun in a specially designed spinning manifold. Separate extruders and metering pumps are used for both components. Ratio of the polymers can be controlled by varying the speed of the metering pumps. Spinning of Bicomponent Fibers
  8. 8. Figure 1. Photograph of a Bicomponent Spinning Machine Figure 2. Sketch showing parts of Bicomponent Spinning Machine
  9. 9. Core-Sheath Bicomponent Fibers • In core sheath structure, one of the components called core is fully surrounded by the second component known as sheath. In this configuration, different polymers can be applied as a sheath over a solid core of another polymer, thus resulting in variety of modified properties while maintaining the major fiber properties. Figure 3. Different types of bicomponent fibers a)-d)Core–sheath, e) Eccentric core- sheath and f)Multiple core-sheath
  10. 10. • Concentricity/eccentricity of the core can be tuned according to end application. If the product strength is the major concern, concentric bicomponent fibers are used; if bulkiness is required at the expense of strength, the eccentric type of the fiber is used. Core-Sheath Bicomponent Fibers
  11. 11. Applications of Core-Sheath Bicomponent Fibers • Core imparts strength (reinforcing material) and sheath has dye ability, soil resistance, heat-insulating, and adhesion properties. Some examples include: • bonding fibers used in carpets, upholstery etc., where the sheath is made of PE and core is made of high melting point material like nylon. • antisoil-antistatic fibers, made using a PET-PEG block copolymer containing polyester core. • Sheath can be made from expensive material to increase visual appearance. And the core can be of low cost material to control cost. • For making self crimping fibers. Crimp can be controlled by changing the eccentricity. Eccentricity of core can be varied to balance strength and bulkiness: used in pillows and furniture. • In a simple technique to produce core sheath fibers, the two polymer liquids are separately led to a position very close to the spinneret orifices and then extruded in a core sheath form as shown in Figure 4.
  12. 12. Figure 4. Technique for Core-Sheath Fiber formation
  13. 13. Core-Sheath Bicomponent Fibers • In case of concentric fibers the core polymer is in the center of the spinning orifice outlet and flow of the core polymer fluid is strictly controlled to maintain the concentricity of both components, while eccentric fiber production is based on following approaches: • Eccentric positioning of the inner polymer channel and controlling of the supply rates of the two component polymers. • Introducing a stream of single component merging with concentric sheath-core component just before emerging from the orifice. • Deformation of spun concentric fiber by passing it over a hot edge. • Coating of spun fiber by passing through another polymer solution. • Spinning of core polymer into a coagulation bath containing aqueous latex of another polymer.
  14. 14. Side by Side Bicomponent Fibers • These fibers contain two components lying side-by-side. Both components are divided along the length into two or more distinct regions. These are generally used to make self-crimping fibers due to different shrinkage characteristics of the two components. In some applications, different melting temperatures of the fibers are taken advantage of when fibers are used as bonding fibers in thermally non woven waves. • Generally, the two components must show good adhesion. however, side by side fibers can also be used for producing the so called splitable fibers which split in a certain processing stage yielding fine filament of a sharp edge cross section.
  15. 15. Figure 5. Schematic showing melt spinning of side by side bicomponent fibers
  16. 16. Multi layer, fine or microfibers • After the commercialization of self-crimping bicomponent fibers in 1960’s, attempts were made to multiply the conjugating structure to produce much complicated bicomponent fibers, also sometimes referred to as multilayer fibers. After development of multilayer fibers around 1965, the fibers were split (as shown in Figure 6) to produce super fine fibers /microfibers.
  17. 17. Figure 6. Evolution of Microfibers
  18. 18. • Besides direct spinning most other techniques for the production of microfibers involve the spinning of a multicomponent filament from which smaller sub units are isolated by splitting. Some examples of microfibers produced by separation /splitting are summarized in Figure 7.
  19. 19. Figure 7. Microfiber produced by separation/splitting
  20. 20. Segmented Pie • These are made from alternate wedges made from two different polymers. The number of wedges is around 16 to 32 and the spinning manifold is complicated. The fiber is drawn to high draw ratio and sometimes splitting may occur while drawing. • The splitting is carried out by partial or complete dissolution of one component. Fibers obtained are of fine denier and sharp cross section. • These are used for making non-woven web with ultra fine fibers. The resultant fabric is stronger and has higher surface area.
  21. 21. Figure 8. Segmented pie bicomponent fibers Figure 9. Schematic showing melt spinning of segmented pie structured fibers
  22. 22. • PET and Nylon bicomponent fiber is split by soaking in a hot caustic solution of 5-10% NaOH. PET and Nylon are separated due to swelling. Figure 10. Schematic showing melt spinning of segmented pie fibres
  23. 23. • Sanding and brushing can also be used for splitting fibers. But it works only with fibers that are easily splitable such as hollow fiber. Figure 11. Radial petal like conjugate fibres: (a) without central hole and (b) with central hole
  24. 24. Islands in the sea • These are also called as matrix-fibril fibers. In cross section there are areas of a polymer (island) in the matrix of the other (sea). These are also used to produce finer fibers. Sheath is made up of a dissolvable material and core is made up of desired material. Sheath is dissolved in proper solvent giving micro denier fibers.

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