Рами: ботаническое описание, свойства и применение

Species of plant
the plant

Ramie (pronounced: '/r//eɪ//m//i/, RAYmee; from Malay rami), Boehmeria nivea, is a flowering plant in the nettle family Urticaceae, native to eastern Asia. It is a herbaceous perennial growing to tall; the leaves are heart shaped, long and broad, and white on the underside with dense, small hairs—this gives it a silvery appearance; unlike stinging nettles, the hairs do not sting. The true ramie or China grass is also called Chinese plant or white ramie. A second type, known as green ramie or rhea, is believed to have originated in the Malay Peninsula. It has smaller leaves which are green on the underside, and it appears to be better suited to tropical conditions.

Ramie is one of the oldest fiber crops, having been used for at least 6,000 years, and is principally used for fabric production. It is a bast fiber, which comes from the inner bark (phloem) of the vegetative stalks and not the woody stem itself or the outer bark. Ramie is normally harvested two to three times a year, but under good growing conditions can be harvested up to six times per year. Unlike other bast crops, ramie requires chemical processing to de gum the fiber. When the plant begins flowering, or just before, it signals both a decline in growth and the plant being at its maximum fibre content, and is harvested. Taiwan's aboriginal people have used ramie for millennia in fabric production and ramie is still used to create traditional garb which is worn in the festivals which have not been banned (mostly related to decapitation and stabbing enemy captives). Ramie was used to produce an open weave fabric called mechera, used for shirts and dressing gowns suitable for warm climates. The French painter Raoul Dufy designed in the early 20th century patterns for prints on mechera used by the French shirtmaker Charvet. Brazil began production in the late 1930s with production peaking in 1971. Since then, production has steadily declined as a result of competition from alternative crops, such as soybeans, and from synthetic fibers. +Physical and chemical properties of ramie fiber Cellulose (wt%) Lignin (wt%) Hemicellulose (wt%) Pectin (wt%) Wax (wt%) Microfibrillar angle (°) Moisture content (wt%) Density (g/cm3) 68.6 – 76.2 0.6 – 0.7 13.1 – 16.7 1.9 0.3 7.5 8.0 1.50

+Mechanical properties of untreated ramie fibers Fiber diameter (mm) Fracture load (N) Tensile strength (MPa) Fracture strain (%) 0.034 0.467 560 0.025

Despite its strength, ramie has had limited acceptance for textile use. The fiber's extraction and cleaning are expensive, chiefly because of the several steps—involving scraping, pounding, heating, washing, or exposure to chemicals. Some or all are needed to separate the raw fiber from the adhesive gums or resins. Spinning the fiber is difficult due to its brittle quality and low elasticity; and weaving is complicated by the hairy surface of the yarn, resulting from lack of cohesion between the fibers. Greater utilization of ramie may depend upon development of improved processing methods and the need to find plastic alternatives. Ramie is used to make such products as industrial sewing thread, packing materials, fishing nets, and filter cloths. It is also made into fabrics for household furnishings (upholstery, canvas) and clothing, frequently in blends with other textile fibers (for instance when used in a mixture with wool, shrinkage is reported to be greatly reduced when compared with pure wool). Shorter fibers and waste are used in paper manufacture. Ramie ribbon is used in fine bookbinding as a substitute for traditional linen tape. For the 2010 Prius, Toyota began using plant derived plastics made from the cellulose in wood or grass instead of petroleum. One of the two principal crops used is ramie. Ramie is also used as an ornamental plant in eastern Asia. In Vietnam, ramie leaves are called "cây lá gai", which is a main ingredient in making "bánh gai" or "bánh ít lá gai", a Vietnamese glutinous rice cake. The leaves give the cake its distinct color, flavor and fragrance. In the Chinese Hakka community, ramie leaves are called "chu yap (苧葉)," which is a main ingredient in making pancake like dumplings with glutinous rice powder, sugar and water. These glutinous rice powder dumplings are known as "ban (粄)" in Hakka or "Cha Kwo (茶棵)" in Cantonese, similar to another Southeast Asian delicacy otherwise known as Kuih. The ramie leaves are picked, cleaned and ground in mortar, mixed into a dough of glutinous rice powder, water and sugar, kneaded thoroughly and placed on palm sized square or circular cut banana leaves and steamed. The ramie leaves give the dumplings a dark green colour and unique aroma. Ramie is also occasionally used in the construction of high performance rowing oar shafts. Mahe Drysdale used sculling oars made with ramie during the 2016 Rio Olympics where he won Gold in the Men's 1X Scull.

China leads in the production of ramie and exports mainly to Japan and Europe. Other producers include Japan, Taiwan, the Philippines, and Brazil. Only a small percentage of the ramie produced is available on the international market. Japan, Germany, France and the UK are the main importers, the remaining supply is used domestically.