PROPERTIES OF KENAF
Kenaf is herbaceous annual plant with a single, straight un-branched stem that grows to a height 4 to 6 metres or 12 to 20 ft. and a diameter of 25 - 50 mm or 1 to 2 inch over a 5 to 7 months growing season in a variety of climatic conditions. Similar to hemp, the stem is characterized by a relatively thin outer layer (referred to as bark or bast) and a wood like core.
The bark constitutes on average about 35 to 40% of the dry weight of the stem, which contains long, slender fibers of length 2.5 to 4mm. The woody core makes up the remaining 60-65% of the stem weight and consist of short fibers that are reportedly a rather constant 0.50 to 0.60mm in length.
Chemically, the kenaf stalk overall is similar to wood. bark fibers of hemp stalk contains significantly more cellulose and holocellulose and significantly less lignin than either of hardwood or softwood. Hemp core on the other hand contains less cellulose than wood.
Non-wood fibers have some features that are superior to wood fibers and others that represent clear disadvantages. Nonetheless it is technically possible to manufacture high quality paper from all of these fibers. A major issue with agriculturally derived fiber is that in most regions of the world this tends to be harvested within a narrow window of time, requiring storage of vast quantities of biodegradable material for periods approaching up to one year. Inventory and storage costs and costs of fiber loss in storage can be significant.
Physical Characteristics of Kenaf and Softwood/Hardwood
| Characteristics | Hemp | Softwood | Hardwood | ||
| Bark | Core | Whole | |||
| Length (mm) | 2.5- 4.0 | 0.5-0.6 | - | 2.5-5.5 | 0.8-1.9 |
| Alfa Cellulose (%) | 51.0 | 34.9 | 40.6 | 42+/-2 | 67+/-5 |
| Holocellulose (%) | 81.1 | 71.6 | 74.9 | 69+/-4 | 80+/-1 |
| Lignin (%) | 11.8 | 18.3 | 16.0 | 28+/-3 | 4+/-2 |
| Extractives (%) | 2.8 | 4.8 | 4.1 | 3+/-2 | 5+/-3 |
| Ash Content (%) | 2.8 | 1.8 | 2.1 | <0.5 | <0.5 |
Kenaf is considered to be one of the highest producers of biomass among plants in terms of tons/land/time. One hectare of kenaf can produce 15-20 tons of dry matter within a short period of only 120 days. One hectare can yield 5 -7 tons of high quality fibers.
