Sel Serat Kapuk Randu (Ceiba Pentandra)

Sel kapuk randu seperti halnya sel kapas berbentuk memanjang, perbedaannya; pada sel kapuk tidak terdapat torsi, sehingga sel kapuk hanya berupa lumen (rongga sel) yang dibatasi oleh dinding sel dengan lingkungan luar. Oleh karena itu sel kapuk mampu menyimpan udara sehingga baik digunakan sebagai bahan isolasi. Serat kapuk banyak digunakan sebagai bahan kasur atau bantal. Biasanya, kasur jika telah lama digunakan, maka sel-sel kapuknya akan terisi minyak yang berasal dari keringat kita, sehingga tidak empuk lagi. Oleh karena itu, kasur tersebut harus dijemur di bawah terik matahari, untuk menguapkan minyaknya, sehingga dapat dipakai kembali.

Serat kapuk berasal dari sel epidermis dari kulit buah. Sel-sel ini mulai tumbuh kira-kira 16 hari sesudah pembungaan, yaitu waktu pembelahan sel telur dan ada kepastian buah tidak rontok. Serat yang sudah tua membentuk lumen yang kosong berdinding tipis dan terisi udara serta tertutup pada kedua ujungnya. Dindingnya licin dan dilapisi lapisan lilin sehingga serat kapuk sangat ringan dan mempunyai kemampuan mengisolasi panas dan suara. Dinding serat kapuk licin dan tidak terpilin sehingga serat kapuk sulit dipintal menjadi benang karena antara serat yang satu dengan yang lain tidak melekat menjadi satu.

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The Kapok Tree

A great natural resource.

The kapok tree, also known as the silk cotton tree, is native to New World and to Africa and was transported to Asia where is cultivated for its fiber, or floss. The kapok's huge buttressed trunk tapers upwards to an almost horizontal, spreading crown, where large compound leaves are made up of five to eight long, narrow leaflets. In full sun, the kapok can grow up to 4 meters (13 feet) per year, eventually reaching a height of 50 meters (164 feet).

The kapok tree is deciduous, dropping its foliage after seasonal rainy periods, thus ridding it of damaged leaves while purging the tree of fungi, herbivorous insects, and other organisms. This loss of leaves also improves access for the bats that feed on the sugar-laden nectar of kapok blossoms. In doing so, the bats unwittingly pollinate the tree's flowers. The flowers open at night and have five petals that are white or pink on the outside. Only a few flowers on a given branch will open on any particular night during the two or three weeks that the tree blooms.

Kapoks do not bloom every year, and some may go 5–10 years without flowering. When the tree does bloom, however, it is prolific, producing up to 4,000 fruits measuring up to 15 cm (6 inches) long. Eventually these pods open on the tree, exposing the pale kapok fibers to the wind for dispersal. The fibers, in which over 200 seeds are loosely embedded, are sometimes referred to as silk cotton and are yellowish brown, lightweight, and lustrous.

In harvesting of the great kapok fiber, the pods are either cut down or gathered when they fall, then broken open with mallets. The seed and fiber, removed from the pods by hand, are stirred in a basket; the seeds fall to the bottom, leaving the fibers free. The seeds may be processed to obtain oil for making soap, and the residue is used as fertilizer and cattle feed.

Although kapok wood does not hold screws or nails well, the timber is used for a variety of wood products, including paper. Local peoples have long used kapok logs for carving into canoes. The genus name of the true kapok, Ceiba, likely derives from a Carib word for a dugout boat.

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About Kapok Fiber

Kapok fiber is one of the natural cellulostic fibers which grow on the kapok plant. It has a hollow body and a sealed tail, which are desirable features of candidates for functional textiles of this nature. However, the low volume weight of kapok is (specific density 0.29g/cm3), and the short length and smooth surface of the fibers, causing poor inter-fiber cohesion, have prevented kapok from being processed by modern spinning machines.

Kapok are silky fibers that clothe the seeds of the ceiba tree of the family Bombacaseae. Kapok fibers have rich oiliness and do not have high strength and, therefore cannot be spun economically. It is conventionally used as a stuffing, especially for life preservers, bedding, and upholstery, and for insulation against sound and heat.

The Kapok fiber has a hollow structure with external radius around 8.25 (±4) _m, internal diameter around 7.25 (±4) _m, and length around 25 (±5) mm. Combined with the specific material density of 1.3 g/cm3 , large pore volume in Kapok assembly is available for NAPL sorption. Typical analyses indicate that the Kapok fibers comprise 64% cellulose, 13% lignin and 23% pentosan. Besides these constituents, they also contain wax cutin on the fiber surface which makes them water repellent not with standing they are preponderantly composed of cellulose.

Kapok finds use in bedding and upholstery industries, in the production of life-saving equipment, and in the construction of thermally insulated and soundproof covers and walls. On account of its buoyancy, freedom from water-logging and weight-bearing capacity, it is the material par excellence for the manufacture of lifebuoys and belts, waistcoats and other naval life-saving appliances. The buoyancy of kapok is about five times as great as that of cork and about three times that of reindeer hair. During the war, kapok was employed for insulating tanks, for lining aviation suits, for filling floats of army assault-bridges, and generally for replacing cork wherever lightness, moisture-resistance and floating power were needed.

The kapok fiber once used in floatation vests and has been used as building insulation has a hollow fiber and looks like glass fiber under the microscope. The hollow fiber has air inside allowing combustion deep inside the material. Smoldering fire and open flame travel quickly within the material.

• The Kapok tree is a deciduous tree that can be found in the forests of Asia and Middle America.
• It grows up to 70m and it has capsular fruits, which are picked and opened by hand.
• The fibers of the fruits are air-dried and not treated with chemicals.
• Kapok is a natural fiber that is completely biodegradable.
• The natural bitter constituents of the Kapok fiber are anti-bacterial and anti-microbial therefore
• Moths, mites and other microorganisms cannot infest the toy.

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