What are the properties of kapok fiber?

• Kapok fibers consist of natural microtubules with fine tube structure.
• Longitudinal and Cross-section: The longitudinal section of kapok fiber shows a smooth cylindrical surface, while a cross-sectional view consists of a wide-open lumen. Kapok fiber has a unique hollow structure, and this property is believed to contribute towards a large surface area.
• Kapok fiber also has the presence of five-layer structure i.e. are cuticle, primary wall, secondary wall, tertiary wall and inner skin.
• Length and Density: The length of kapok floss or fibers is about 10-35 mm in length and has a density of about 0.4-0.7 decitex which accounts for approximately half of the density of cotton. The low density of kapok is due to wide lumen
• Colour and Lustre: The kapok fibers are lustrous but brittle and tend to break out. The colour of kapok fibers ranges from yellowish to light brown. Kapok fiber is odourless, fluffy, nontoxic, nonallergic, and resistant to rot and mildew.
• Thermal Insulation: Kapok fibers are good thermal insulators owing to its hollow interior that constitutes 80% of its entire volume and their insulating power is even greater than wool.
• Since kapok has a large surface area and hollow structure, the fiber exhibits outstanding moisture transfer properties.
• Water Repellency: Kapok fibers are water-repellent or hydrophobic due to the presence of waxy surface and possess an outstanding oil absorbency and retention capacity due to the large lumen in its structure.
• Sound Absorption: Kapok fibers possess an ability to absorb unwanted sounds due to its hollow structure.
• Spinning Quality: Kapok fibers are short in length, low cohesion property (ability to be spun into yarns), and low elasticity are all the factors that make it difficult to produce yarns from kapok fibers alone and hence they may be blended with other fibers.
• Weaving: The kapok fibers have a very smooth surface and hence slip over one another making them difficult to be woven into a textile material and hence this can be overcome by either treating the fibers with chemicals or plasma treatment that removes the waxy substance from the surface of kapok fiber, this can be accomplished by plasma treatment or use of chemicals. Another method that can be employed is to weave the kapok fibers with other naturally available fibers such as cotton, jute, flax etc. forming a blend.
• Dyeing: Since the kapok fibers are water-repellent and have a presence of waxy coating, they do not permit the water-soluble dye molecules to enter the fabric and hinder in the process of dying. Pre-treatment of kapok fiber is thus important to enhance the dyeing property.
• Antibacterial Property: Kapok fiber due to high lignin content is not easily attacked by cellulosic bacteria and thus imparts antibacterial property.