Banana Fibers – Natural Plant/Bast Fibers

Banana fiber is a natural fiber with high strength, which can be blended easily with cotton fiber or other synthetic fibers to produce blended fabric & textiles. Banana Fiber also finds use in high-quality security/ currency paper, packing cloth for agriculture produce, ships towing ropes, wet drilling cables etc.

Banana fiber, a lignocellulosic fiber, obtained from the pseudo-stem of banana plant (Musa sepientum), is a bast fiber with relatively good mechanical properties.

Plant fibers are sclerenchymatous cells with heavily lignified cell walls having a narrow lumen in cross section. Fiber cells are dead at maturity and serve as a support tissue.

Natural fibers possess several advantages over synthetic fibers such as low density, appropriate stiffness and mechanical properties and also high disposability and renewability. Also, they are recyclable and biodegradable.

Banana fibers can be used for various purposes such as in textile, paper or handicrafts industry. Banana paper is versatile as it is waterproof and stronger than wood-pulp paper, meaning it can be used in packaging and even as a basis for building materials.

Technology / Process

There are two methods for extraction of Banana fiber, namely Bacnis method and Loenit method.

• In the Bacnis method, Banana Fiber is produced from the waste stalk of Banana plant. The outer sheath is tightly covered layers of fiber. The fiber is located primarily adjacent to the outer surface of the sheath and can be peeled-off readily in ribbons of strips of 5 to 8 cm wide and 2-4 mm thick, the entire length of the sheath.
• This stripping process is known as tuxying the strips being called tuxies. Two methods of tuxying are employed in the Philippines. In the first method called Bacnis method, the trunks are pulled apart and the sheath separated according to their position in the stalk. They are then flattened and the fiber is stripped from the stem by cutting the pulpy portion and pulling away from the tuxy.
• In the Loenit method, the tuxies are pulled off the stalk from one sheath at a time. In either of these methods, tuxies are tied into bundles of 23 to 27 kg and brought to the stripping knife for cleaning. In this process, tuxies are pulled under a knife blade, which is pressed tightly against the tuxy in order to scrape away the plant tissue between the fibers. The clean fiber is then air dried and made up into bundles for subsequent grading and bailing.
• In addition to hand stripping, machines are used where the trunks from which the dark outer sheaths have been removed, are cut into sections of 120 to 180 cm in length. The sections are then crushed between rolls and the pulpy tissues are scraped away, one half the length at a time, by two large revolving drums, the rim of which is fitted with scrapping blade which scrapes the sheath while it is pressed against a bed plate, oven dried, graded and baled.

Banana Fiber – Structure and Usage

Banana fibers can be extracted by employing chemical, mechanical or biological methods. The chemical method causes environmental pollution, while mechanical method fails to remove the gummy material from the fiber bundle surface. Biological procedures yield more fiber bundles than the other two procedures without any harm to the environment. The extraction of banana fibers using biological natural retting has already been reported. After extracting the fibers, degumming is essential prior to the utilization of fibers. The removal of heavily coated, non-cellulosic gummy material from the cellulosic part of plant fibers is called degumming.

Banana fiber is multiple celled structures. The lumens are large in relation to the wall thickness. Cross markings are rare and fiber tips pointed and flat, ribbons like individual fiber diameter range from 14 to 50 microns and the length from 0.25 cm to 1.3 cm, showing the large oval to round lumen.

The ‘‘pseudo-stem’’ is a clustered, cylindrical aggregation of leaf stalk bases. Banana fiber at present is a waste product of banana cultivation and either not properly utilized or partially done so.

The extraction of fiber from the pseudostem is not a common practice and much of the stem is not used for the production of fibers. The buyers for banana fibers are erratic and there is no systematic way to extract the fibers regularly. Useful applications of such fibers would regularize the demand which would be reflected in a fall in the prices.

Bast fibers, like banana, are complex in structure. They are generally lignocellulosic, consisting of helically wound cellulose microfibrils in an amorphous matrix of lignin and hemicellulose. The cellulose content serves as a deciding factor for mechanical properties along with microfibril angle.

A high cellulose content and low microfibril angle impart desirable mechanical properties for bast fibers. Lignins are composed of nine carbon units derived from substituted cinnamyl alcohol; that is, coumaryl, coniferyl, and syringyl alcohols. Lignins are associated with the hemicelluloses and play an important role in the natural decay resistance of the lignocellulosic material.