Chaptar (2.9 )Properties of Vegetable/Plant/Cellulosic fibres

Chemically, cotton is the purest vegetable fibre, containing >90% cellulose with little or no lignin.

Vegetable/Cellulosic Fiber Properties

Chemically, cotton is the purest vegetable fiber, containing >90% cellulose with little or no lignin. The other fibers contain 40–75% cellulose, depending on processing. Boiled and bleached fiax and degummed ramie may contain >95% cellulose. Kenaf and jute contain higher contents of lignin, which contributes to their stiff- ness. Although the cellulose contents are fairly uniform, the other components, eg, hemicelluloses, pectins, extractives, and lignin vary widely without obvious pattern. These differences may characterize specific fibers. Except for the seed-hair fibers, the vegetable fibers of bast or leaf origins are multicelled and are used as strands.
In contrast to the bast fibers, leaf fibers are not readily broken down into their ultimate cells. The ultimate cells are composites of micro- fibrils, which, in turn, are comprised of groups of parallel cellulose chains. Bast and leaf fibers are stronger (higher tensile strength and modulus of elasticity) but lower in elongation (extensibility) than cotton. Vegetable fibers are stiffer but less tough than synthetic fibers. Kapok and coir are relatively low in strength; kapok is known for its buoyancy.

Chemical Composition of Vegetable Fibers, wt %

Fiber	Cellulose	Hemicellulose	Pectins	Lignin	Extractives
Bast Fibers
Flax	71.2	18.6	2.0	2.2	6.0
Hemp	74.9	17.9	0.9	3.7	3.1
Jute	71.5	13.4	0.2	13.1	1.8
Kenaf	63.0	18.0	-	17.0	2.0
Ramie	76.2	14.6	2.1	0.7	6.4
Leaf Fibers
Abaca	70.1	21.8	0.6	5.7	1.8
Phormium	71.3	-	-	-	-
Sisal	73.1	13.3	0.9	11.0	1.6
Seed-hair Fibers
Coir	43.0	0.1	-	45.0	-
Cotton	92.9	2.6	2.6	-	1.9
Kapok	64.0	23.0	23.0	13.0	-

 

Dimensions of Ultimate Fibers and Strands

	Ultimate fiber		Cell cross-section		Fiber strand
Fiber	Length,mm	Diameter,µm	Shape	Diameter,µm	Length,cm	Width,mm
Bast Fibers
Chinese Jute	2-6.5	7.33
Flax	4-69	8-31	Polygonal	8.8-16.1	25-120	0.04-0.62
Hemp	5-55	16	Polygonal	13.1-23.6	100-400	0.5-5
Jute	0.7-6	15-25	Polygonal-Oval	12.3-18.6	150-360
Kenaf	2-11	13-33	Cylindrical		200-400
Ramie	60-250	16-120	Hexagonal-Oval	6.2-32.4	10-180
Sunn	2-11	13-64	Irregular	13.6-24.6	108-216
Nettle	4-70	20-70		50-50
Leaf Fibers
Abaca	2-12	6-40	Oval-Round	14-20	150-360	0.01-0.28
Cantala				13.8-16.4
Caroa	2-10	3-13		3.2-8.2
Henequen	1.5-4	8.3-33.2		11.6-22.2
Istle		9.6-16		1.2-13.4	30-75
Mauritius	1.3-6	15-32	Cylindrical		124-210
Phormium	2-11	5-25	Round	10-3-12.5	150-240
Sansevieria	1-7	13-40
Sisal	0.8-7.5	8-48	Cylindrical	11-16	60-120	0.1-0.5
Seed-hair Fibers
Coir	0.2-1	6.24				1
Cotton	10-50	12-25	Circular Elliptical		1.5-5.6	0.012-0.025
Kapok	15-30	10-30	Round		1.5-3	0.03-0.036
Other Fibers
Broom Root			Others		25-40

  

Mechanical Properties of Vegetable Fibers

Fiber	Fineness km/kg	Tensile Strength, km	Elongation %	Modulus of Elasticity, N/tex	Modulus of repture, mN/tex
Bast (soft) fibers
Flax		2470	2-3	18-20	8-9
Hemp	139	38-62	1-6	18-22	6-9
Jute	489	25-53	1.5	17-18	2.7-3
Kenaf	180	24	2.7
Ramie		32-67	4.0	14-16	11
Urena	342	16	1.9
Leaf (hard) fibers
Abaca	32	32-69	2-4.5		6
Cantala	58	30
Henequen	32	20-42	3.5-5
Istle	34	22-27	4.8
Phormium	38	26
Sansevieria	118	43	4.0
Sisal	40	36-45	2-3	25-26	7-8
Seed-har fibers
Coir	18	16	4.3	16
Kapok	16-30	1.2	13	10