Date Palm Fiber: Properties, Chemical Treatments & Applications

Introduction
Fiber from Date Palm and producing quality yarn from that, has anyone ever imagined? For the first time in the world, Egyptian researchers at the Consortium have developed high-performance sustainable textile fibers from date palm byproducts like fronds, leaves, leaflets, rachis etc. The aim of this study was to extract high-performance fiber from the byproducts of date palm using a combined alkaline-mechanical process and to study the identification of physiochemical, morphological and mechanical properties.

Physical and Mechanical Properties of Date Palm Fiber

Even this fiber is produced from the byproducts of date palms, deforestation or food crisis will not create any such problems. This particular fiber has certain properties such as- 100% biodegradable and compostable, structurally tensile strength is 5 times higher than steel and same as flax & sisal, thermal insulation properties are higher than carbon fiber. Physical properties of the natural fibers are crucial in determining their quality for various industrial applications as well as natural fiber composites. Mechanical properties of natural fibers are powerfully affected and determined by many necessary variables like structure, micro-fibrillar angle, chemical composition, cell dimensions and defects.

Some specific characteristics of date palm fiber are mentioned below-

Length: 20-250 mm
Diameter: 100-1000 μm
Density: 0.9-1.2 g/cm3
Specific Modulus: 7 approx.
Thermal Conductivity: 0.083 W/m K
Tensile Strength: 58-203 MPa
Elongation at Break: 5-10%

Sources of Date Palm Fiber
There are more than 140 million date palms in the Middle-East and North Africa. Egypt is currently the largest producer of dates, as are Iran, Saudi Arabia, UAE, Pakistan and Sudan. More than 48.8 million tons of waste is generated every year by pruning date palms for agriculture. So, the production of date palm fiber is currently a big success. Sustainable textile fibers are found in all these countries from date palm byproducts such as fronds, leaves, leaflets, rachis, fruit branches etc.

Chemical Composition(%) of Date Palm Fibers

Constituents	Cellulose	Hemicelluloses	Lignin	Ash	Extractive
Leaflet	40.21	12.80	32.2	10.54	4.25
Leaf	54.75	20.00	15.30	1.75	8.20
Rachis	38.26	28.17	22.53	5.96	5.08

The primary cell-wall and other secondary walls of date palm fibers consist of a series of helically wound cellular micro-fibrils formed from long chain cellulose molecules can determine the mechanical properties of fiber. Every cell-walls are formed from three main components which are cellulose, hemicelluloses and lignin. Cellulose and lignin are the vital structural components in maximum natural fibers. Although celluloses are resistant to hydrolysis, strong alkali and oxidizing agents, also cellulose is degradable to some extent when exposed to chemical treatments. On the other-hand lignin is a complex hydrocarbon polymer and it usually gives rigidity to plant and assists in water transportation.

Research Activities
The researchers have done a lot of research to enhance the extraction process and have been able to do a wide assortment of these new fibers. They performed various physical, chemical and mechanical treatments like heat stability, surface properties, tensile strength, density etc. on date palm fibers and compared it with other natural fibers such as jute, hemp, coir etc. they observed that the thermal degradation and tensile strength of the fiber increased slightly after caustic soda treatment.

The results of their research on date palm fibers have been well received by the scientific community, with research and reviews of the most prestigious scientific journals such as Elsevier and Springer distinguishing the results of this study. The fiber is also well recognized by the Egyptian industrial community and is being used in the spinning lines of the center of Egyptian Industries.

Chemical Treatments

1. Alkaline Treatment: Alkaline treatment is an important and main chemical treatment of natural fibers. The major modification done by this treatment is that the disruption of hydrogen bonding within the network structure, here with increasing surface roughness. Here aqueous NaOH is used to remove the lignins, wax and oils from the cell walls. Thus, alkaline treatment is often directly affected the cellulosic fibril, the degree of polymerization and therefore the extraction of lignin and other non-cellulosic compounds.

Figure 3: Scanning Electron Microscope for (a)Untreated Date Palm Fiber, (b) Treated Date Palm Fiber with 1.5% NaOH

2. Liquid Ammonia Treatment: Liquid ammonia has the power to penetrate quickly to the inside of cellulosic fibers, forming a complex compound after the rupture of H-bonds. This ability of ammonia is due to its low viscousness and surface tension. The liquid ammonia treatment results in deconvolution and smoothing of the surface of natural fibers. At the same time, the cross-section of fiber becomes round and lumens decrease.

3. Esterification: Esterification is one of the important chemical treatment methods usually involves the reactions with organic acids or anhydrides. Esters containing 1-4 carbon atoms are named respectively formate, acetate, propionate and butyrate; laurate has 12 carbon atoms and stearate has 18 carbon atoms. Such treatment modification may alter polarization of the fibers to form them more compatible to non-polar matrix.

End Uses of Date Palm Fibers
At first the researchers extracted long textile fiber from the byproducts of date palms, and then converted it into fiber tow, chopped fibers, yarn, non-woven mats, woven fabric etc. Date palm fibers can be easily mixed with other long fibers like sisal, flax or abaca fiber. It is also possible to make yarn by mixing it with hemp or jute. These fibers derived from date palms are not only durable but also economical in production and compatible with textile & composite processing. In particular, these fibers provide the necessary features for the manufacture of future lightweight cars, sports goods, construction plaster reinforcement, sacks for packaging, rope, yarn and other products.

Conclusion
The growing demand for sustainable and renewable textile materials is increasing the interest in natural fibers. Natural fibers are not only environment friendly but also have high precision properties due to their light weight characteristic. Currently date palm is considered as one of the sources of natural fibers. Fiber can be extracted from different parts of the date palms. Due to the abundance of dates in the Middle East, the annual pruning yields a large number of byproducts. Researchers are conducting various experiments and study on this fiber, which will help researchers to better understand about the date palm fibers and to determine how these fibers will be used to create new textile products.

References:

Dr. Mohamad Midani, Dr. Naheed Saba, Dr. Othman Y. Alothman, “Date Palm Fiber Composites”, Publisher: Springer Singapore.
AL-Oqla F M, Alothman O Y, Jawaid M, Sapuan S M, and Es-Saheb M H 2014 Processing and properties of date palm fibers and its composites Biomass bioenergy 1-25
https://textilevaluechain.in/2020/07/17/first-long-textile-fibre-from-date-palm-by-products-developed-by-researchers-in-egypt/. Accessed date: 19/02/21
https://www.researchgate.net/publication/265085416_Processing_and_Properties_of_Date_Palm_Fibers_and_Its_Composites, Accessed date: 19/02/21
W Ghori, N Saba, M Jawaid and M Asim, “A review on date palm (phoenix dactylifera) fibers and its polymer composites”

Author of this Article:
Md. Imran Hossain
B.Sc. in Textile Engineering
Shahid Abdur Rab Serniabat Textile Engineering College, Barisal.
Email: mdimranhossain.te@gmail.com

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Mazharul Islam Kiron

Founder & Editor of Textile Learner. He is a Textile Consultant, Blogger & Entrepreneur. He is working as a textile consultant in several local and international companies. He is also a contributor of Wikipedia.