Cannabis is a woody annual plant from the Cannabinaceae family. Cannabis, whose homeland is Asia, has spread all over the world in various ways. Today, there are two subspecies. These; Cannabis sativa and Cannabis indica. The type that is important for industrial applications and used in fiber production is Cannabis sativa. Other type's production is illegal almost all over the world because it can be used for drug production. Cannabis is one of the first cultivated plants in human history.
The species, Cannabis Sativa, was first found as a medicinal plant in China in 2700 BC, passed from Asia to Europe 2000-2200 BC and has been cultivated until today. As a result of archaeological research, remains of fabric made from hemp dating back to 8000 BC were found. According to Turkish written sources, it is known that cannabis cultivation in Anatolia was made in 1500 BC.
Hemp fibers have had an important place in textiles throughout history and have shaped the economies of the countries. In fact, hemp fiber was the raw material of 80% of textile products in the world until the 20th century. At the beginning of the 20th century, with the use of cotton fiber with the developing technology, thinner yarns were produced and it became possible to produce lighter clothes. The laws against cannabis enacted in the 1930s caused a great decrease in hemp production, and textiles obtained from hemp began to lose its importance together with the synthetic fibers developed. In Turkey, it is cultivated in the provinces of Amasya, İzmir, Kastamonu, Kayseri, Kütahya, Samsun and Sivas. Cannabis, which has a very wide usage area, has been cultivated only in Samsun Vezirköprü and Kütahya in recent years.
Compared to cotton and petroleum-based synthetic fibers, which are the most widely used natural fibers in the world, hemp fibers attract attention with their organic production possibilities in textiles and their prominent environmental features. Hemp is a natural fiber that provides high strength, durability and absorbency. The annual fiber yield is quite high and there is no pilling problem in the fabrics produced from these fibers. Hemp absorbs 12% moisture at 65% RH at 20°C and 30% at 95% RH, and these values are much higher than cotton and linen. Good electrostatic properties, UV protection and anti-allergic properties are other properties that can be brought to the textile material by using this fiber. Hemp fibers are converted into short staple fibers by chemical or biological processes, such as flax fibers, in the cotton-like (cottonization) process so that they can be mixed with fibers with short fiber lengths. It demonstrates its suitability for organic agriculture production aiming to protect the soil and the environment, due to reasons such as the lack of high water consumption in the production of hemp fibers and the ability to grow without the need for fertilizers and pesticides. Additionally, since hemp is a crop suitable for crop rotation, it destroys weeds, leaving a rich soil structure for the next crop.
Obtaining Fiber from Hemp
In the textile industry, the male sexual individuals of cannabis sativa type cannabis are used to obtain fiber. The plant has a gnarled, long stem and there are different categories of fibers in the stem section. Primary fibers are suitable for textile use and these fibers are found in the shell part and consist of reptilian tissue. During the growth process of the plant, the number of fibers does not change, but the fibers are elongated. The distance between the nodes determines the fiber length, the fiber thickness increases towards the bottom of the body. Hemp fibers consist of fiber bundles and each fiber cell is 20-35 microns. The glossy hemp fibers are yellow-brown and the cross-section of the fiber is polygonal.
The characteristic features of the fibers vary according to the harvest period of the plant. For this reason, it is important to choose the right harvest period in order to obtain the desired fiber quality product. The process of separating the fibers from the stems after the harvest of the hemp plant is similar to the methods of obtaining flax fiber. There are methods such as mechanical separation, dew-holding, pooling, chemical treatment and enzyme application for the separation of fibers from the stems. The process performed here is to reveal the fibers by removing the woody parts of the stems. Basically, 3 different methods are applied to obtain fiber from the harvested and seeded hemp stalks; biological pooling method, mechanical method, chemical method.
Biological Pooling Method
In this process, cannabis stalks are laid on the fields and left under the influence of microorganisms. In regions with high moisture content, this process, which is carried out in the spring and autumn seasons, facilitates the reproduction of fungi with the effect of temperature and humidity. In this method, which takes place in a period of at least 1.5 months, since the decay is slow, soft and thin fibers are obtained.
It is a method that provides fiber by separating the fibrous regions and woody parts from each other by breaking and crushing the stems of the cannabis plant. Although this method is a faster and more economical method compared to the pooling method, the obtained fibers are harder. Since it is not possible to remove the intercellular pectin by mechanical means, the mechanical method is not suitable for the production of fibers used in textiles.
It is the most suitable method after the enzyme method, which is suitable for the production of fiber from hemp. Clean, equal length fibers are obtained, free from stalks and garbage. In this method, hemp stalks are first cut and cooked under certain pressure in an alkaline bath. It is washed with plenty of water and shaken to remove pectin. Afterwards, dried hemp fibers are mixed with cotton and similar fibers to obtain yarn. However, nowadays, cold or hot pooling methods are being re-evaluated, and at some points, hemp fiber producers are said to have some drawbacks. Because the oxygen ratio in the water is reduced in large amounts during pooling and it contains organic substances after the treatment, which is considered harmful in terms of environmental pollution. Countries that are sensitive to environmental pollution have intensified their research by considering these factors. Especially France and the Netherlands apply the new production methods they have developed for hemp in the textile and paper production industry.
Usage Areas of Hemp
The demand for textile products produced from hemp fibers is increasing day by day due to the increase in ecological concerns in people with the increasing level of awareness. In addition, the superior performance and usage properties of hemp fibers due to their physical and chemical structures attract the attention of customers in the market. Hemp fibers, which are the only plants that can be visually distinguished in nature, are generally used on a sectoral basis in the world;
• In drug making,
• In paper making,
• In fuel production (biofuel),
• In all textile products,
• In the automotive sector,
• In petrochemical applications,
• In making cosmetics and soap,
• In electricity production,
• In the construction sector,
• In the feed industry,
• In oil production,
• In asphalt and road construction.
Hemp is widely used in paper, textile, construction, insulation, agriculture, composites, automotive, medicine, etc. It is cultivated for its fibrous stem used in fields. Thanks to its long fiber structure, it can be applied to fancy yarn works, special weavings, canvases and original works. One of the promising applications for hemp fibers is the production of insulation products and fiber-reinforced composites due to their low density and good mechanical properties. Because of its efficiency and high cellulose content, hemp is also an interesting material for energy and biofuel production.
From a sustainability point of view, it is suitable for organic agriculture production, which aims to protect the soil and the environment, due to the fact that there is no high water consumption in the production of hemp fibers and that it can be grown without the need for fertilizers and pesticides. Since hemp is a plant suitable for crop rotation, it destroys weeds and leaves a rich soil structure for the next crop. In addition, 1 acre of hemp can produce as much oxygen as 25 acres of forest. In the world, industrial hemp fibers are accepted as an interesting sustainable material with different properties such as strength, durability, insulation and resistance to ultraviolet rays. The potential use of hemp fibers in agricultural areas is considered to provide a sustainable solution for the repair of soil slopes and landfill systems. Considering the great need and awareness of environmental impact, the performance and recyclability of hemp material, as well as its compatibility with application studies in different disciplines, cause it to be a higher priority in engineering product design recently.
Cars whose bodies are made of hemp are ten times more durable than those made of steel. In the 1930s, Henry Ford developed a car prototype from biological alloys using hemp fibers. These vehicles, which were advertised and whose durability feature was emphasized, could not be put into mass production due to policies.
Today, the value of the used cannabis is better understood and it is the legal production possibilities of the growers in the world. In the product range for products made from hemp fibers, it can be used in a wide range of applicability areas and superior properties in terms of the textile industry in the world, which consists of textile products. While it is priced high for enhancement wear to evolve Cannabis, it is preferable for a group to be for the season, to compensate for a downside.
The hemp clothing industry in America today relies on fiber, hemp yarn and fabrics imported from Eastern Europe and China. Hemp yarns used in clothing and underwear products such as jackets, shirts, dresses, trousers, T-shirts, skirts, upholstery fabrics, towels, curtains, mats, bags, bags, sacks and awnings, such as coarse woven fabrics (canvas) made of hemp fiber, are more than 25 thousand. It is stated that it is used in many products. In the new trends of the clothing industry, sustainable design and ethical fashion seem to be words that we will hear more often in the coming years, so we can say that the increasing trend of hemp plant and hemp yarn production will continue.
Seher KAYA, Eren ÖNER. The Journal of Graduate School of Natural and Applied Sciences of Mehmet Akif Ersoy University 11(1): 108-123 (2020)