What are the properties of hemp fiber?
• Structure: The stalk of the hemp plant consists of two layers: the inner layer and the outer layer. The outer layer also known as the bast layer contains the textile fibers while the inner layer consists of a woody pith surrounded by woody core fiber, which is often referred to as hurds utilised for fuel, building material, garden mulch and animal bedding.
The fibers are present in the form of bundles in the inner layer are shorter and finer.
• Hemp consists of multilayered cell walls which are mainly primary cell wall and secondary cell wall. The secondary cell wall further has three more layers. Although the lignified fibers exist in the middle lamella.
• Cross-section of hemp fiber is of irregular shape or polygonal throughout its length.
• Length: The length of hemp fiber ranges from 4-6 feet. The individual hemp cells are about 0.5-1 inch in length.
• Colour: The colour of hemp fibers ranges from yellowish-grey to dark brown.
• Lustre: The fibers are highly lustrous as the incident light reflects evenly when projected on the fiber surface.
• Tenacity: The hemp fibers are strong and durable. Although these fibers are quite stiff due to the presence of lignin.
• Hemp fiber has an outstanding resistance to degradation by heat and pilling.
• Breathability: The hemp fibers are highly breathable because they are lightweight and quickly absorb moisture making them absolutely comfortable clothing for hot and humid conditions.
• Resistance of mildew: Hemp fibers are resistant to decay caused by moulds, moths and microbes.
• Effect of Acids: Hemp fibers can not withstand the action of hot dilute acids and cold concentrated acids.
• Effect of Alkali and Organic Solvent: Hemp fibers are resistant to alkalis and organic solvent.
• Dye-uptake: The hemp fibers are dyeable and show good attraction towards dye molecules.
• Laundering: Hemp fibers are resistant to shrinkage on washing and these fibers also exhibit the property that they soften and do not worn out on washing thus resulting in keeping the fibers intact. Thus, the hemp fibers do not rot on exposure to water.
• Flexibility: The factor that affects the flexibility of hemp fiber is fineness of the fiber bundles. Generally, the fiber bundles possess low elongation and high flexibility as a result they are difficult to be spun into yarns. Thus, flax and hemp blends are made to solve the problem of flexibility and elongation however this affects the strength of the yarn to a certain extent.