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Kapok or Capok Fibres

The natural, cellulose, seed fibers

Kapok/Capok fiber is one of the natural cellulosic fibers which grow on the kapok plant. It has a hollow body and a sealed tail, which are desirable features of candidates for functional textiles of this nature. However, the low volume weight of kapok is (specific density 0.29g/cm3), and the short length and smooth surface of the fibers, causing poor inter-fiber cohesion, have prevented kapok from being processed by modern spinning machines.

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kapok bollKapok fiber is one of the natural cellulosic fibers which grow on the kapok plant. It has a hollow body and a sealed tail, which are desirable features of candidates for functional textiles of this nature. However, the low volume weight of kapok is (specific density 0.29g/cm3), and the short length and smooth surface of the fibers, causing poor inter-fiber cohesion, have prevented kapok from being processed by modern spinning machines.

Kapok is silky fibers that clothe the seeds of the ceiba tree of the family Bombacaseae. Kapok fibers have rich oiliness and do not have high strength and, therefore cannot be spun economically. It is conventionally used as a stuffing, especially for life preservers, bedding, and upholstery, and for insulation against sound and heat.

The Kapok fiber has a hollow structure with an external radius around 8.25 (±4) _m, internal diameter around 7.25 (±4) _m, and length around 25 (±5) mm. Combined with the specific material density of 1.3 g/cm3 , the large pore volume in Kapok assembly is available for NAPL sorption. Typical analyses indicate that the Kapok fibers comprise 64% cellulose, 13% lignin and 23% pentosan. Besides these constituents, they also contain wax cutin on the fiber surface which makes them water repellent notwithstanding they are preponderantly composed of cellulose

Kapok Tree

Kapok

  • The Kapok tree is a deciduous tree that can be found in the forests of Asia and Middle America.
  • It grows up to 70m and it has capsular fruits, which are picked and opened by hand.
  • The fibers of the fruits are air-dried and not treated with chemicals.
  • Kapok is a natural fiber that is completely biodegradable.
  • The natural bitter constituents of the Kapok fiber are anti-bacterial and anti-microbial therefore
  • Moths, mites and other microorganisms cannot infest the toy.

Kopok Fiber Usage

kapok pillow

Kapok finds use in bedding and upholstery industries, in the production of life-saving equipment, and in the construction of thermally insulated and soundproof covers and walls. On account of its buoyancy, freedom from water-logging and weight-bearing capacity, it is the material par excellence for the manufacture of lifebuoys and belts, waistcoats and other naval life-saving appliances. The buoyancy of kapok is about five times as great as that of cork and about three times that of reindeer hair. During the war, kapok was employed for insulating tanks, for lining aviation suits, for filling floats of army assault-bridges, and generally for replacing cork wherever lightness, moisture-resistance and floating power were needed.

The kapok fiber once used in floatation vests and has been used as building insulation has a hollow fiber and looks like glass fiber under the microscope. The hollow fiber has air inside allowing combustion deep inside the material. Smoldering fire and open flame travel quickly within the material.

  • Kapok was considered unsuitable for textile purposes because the fiber is brittle, smooth and slippery.
  • Refined kapok seed oil is used for the same purposes as refined cottonseed oil. The wood is light and soft and is suitable for making canoes and toys. It is used for matches. The root bark yields a fiber.

Kapok Fiber characteristics comparison with others

Kapok fiber is light, brittle, elastic, lustrous and white or pale yellow in color. Individual fibers are cylindrical, each being a single cell with a bulbous base. The cells of the inner epidermis of the epicarp form the fibers, which are about 1-2 cm long. The air-filled lumen is broad and the wall rather thin. The fiber is, therefore, fragile, which together with the smoothness of the outer surface, makes spinning impossible.

Characteristics Kapok Cotton Air
Average linear density 0.064tex 0.12tex
Average diameter 20.5µm 14µm
Average length 20mm 48mm
Moisture regain 10% 8~13%
Mass density 1.17kg/m3
Thickness 1mm
Specific heat 1027W·s/kg·K
Conductivity 0.026