The comprehensive mechanical properties of pure hemp products are difficult to compare with synthetic materials, but their performance in other aspects is obviously excellent, such as higher friction coefficient and elastic modulus, high hygroscopicity, high oil absorption, Heat resistance and self-degradability, etc. Our country is a big traditional planting country of kenaf, and sacks and hemp ropes are the traditional uses of kenaf. As the market is shrinking year by year due to the impact of synthetic fiber products, actively developing the use of kenaf in manufacturing geotextiles and composite materials based on the characteristics of the material will not only benefit the country and the people, but also have great potential.
Kenaf fiber is rough, stiff, and has poor spinnability. The general count is 1.5~3Nm, and the maximum is no more than 10Nm. It can only be woven in coarse counts. However, the use of non-woven technology can open up a new world for kenaf fabrics.
In farmland infrastructure, environmental engineering, water conservancy facilities, road construction, etc., various geotextiles are increasingly used. Geotextiles made of strong synthetic fibers such as nylon are widely used in dams, retaining slopes, highway roadbeds, etc.
However, the use of three-dimensional geotextiles, needle-punched turf and other products made of yellow and kenaf fibers in soil and water conservation, road greening, and landscaping is a different story.
Hemp products woven into a honeycomb shape have excellent adsorption properties. After being laid on slopes, they can not only retain water but also protect the soil from being eroded by wind and rain. Putting crop seed fertilizer in the honeycomb will quickly germinate and form vegetation. Even if the hemp fiber rots over time, the vegetation will be established and it will be safe for a hundred years.
Kenaf products can be used in modern homes, whether for interior decoration or roof greening. The kenaf wall covering is natural and rustic, and also has the function of breathing, which can regulate humidity and absorb bad gases, allowing you to enjoy healthy benefits. Yellow and kenaf fabrics are used for roof greening, which can make complex projects of thermal insulation and heating a piece of cake.
Kenaf can also be used as a reinforcing fiber for composite materials. Yellow and kenaf have high strength, especially elastic modulus, so they are suitable as reinforcing materials. In some cases, it can even replace expensive carbon fiber. There are automobile manufacturers in Japan that use kenaf and certain tree fingers to make door back panels for luxury cars. They are light, strong and have excellent impact resistance.
According to processing methods and uses, composite materials reinforced with kenaf fiber have the following types:
1. Contact molding method, used to make cruise ships, containers, etc.;
2. Winding method, manufacturing pipe products;
3. Extrusion method, manufacturing chairs, shelves and machine parts, etc.;
4. Filling (resin) board, Used in manufacturing construction, decoration and packaging materials.
Kenaf fiber is a high-quality natural cellulose fiber and an important raw material for the light textile industry. Its fibers are embedded in the phloem of the stems and must be "degummed" to obtain pure fibers for light spinning. For a long time, the degumming method has adopted the "natural water retting method", which occupies a large amount of water, making it difficult to ensure fiber yield and quality. The labor intensity of farmers is high. Regardless of whether it is cold or hot, the operator will stand in the water for a long time, and the retting person will suffer from arthritis. Moreover, retting pollutes both water and air. In addition, because there is no unified standard, the yield and quality of the fiber obtained in this way are difficult to guarantee, which restricts the development of the kenaf industry.
The "Introduction and Digestion of Kenaf Rapid Biological Degumming Technology" project undertaken by the Hemp Research Institute of the Chinese Academy of Agricultural Sciences introduced kenaf rapid degumming fungal cultures from Bangladesh, using special strains for kenaf degumming. , designed their own technical route, developed a kenaf degumming biological preparation for the first time at home and abroad and applied for a patent. They also used the preparation to research and form an "efficient and clean kenaf biological degumming technology" suitable for my country's national conditions, which can Part of the non-cellulosic material undergoes "block collapse" and certain key structural components are completely decomposed, thereby providing nutrients for the life activities of the microorganisms themselves until the kenaf fibers are dispersed.
The results of large-scale production demonstration applications show that the new technology is low-consumption, high-yield, high-quality, and less polluting, and completely eliminates the dirty, slow, and bitter characteristics of traditional methods. Compared with the traditional retting method, the degumming cycle is shortened from the original 9-10 days to 3-5 days; the dry hemp extraction rate is increased by 5 percentage points; the quality of cooked hemp is improved by 1-2 levels; and environmental pollution is reduced by 90% %%, it also saves water surface area and labor force. It is estimated that the comprehensive benefit of increasing income and reducing expenditure per hectare of kenaf reaches more than 1,928 yuan, which is a considerable economic benefit.
Relevant experts analyze that "degumming" is the bridge and link connecting the kenaf planting industry and the processing industry, and is an important processing link in the industrial production of kenaf. Due to the advent of this technology, the key technology that restricts the development of the kenaf industry has been solved. Kenaf production can be vigorously developed in areas with insufficient water sources or water sources, and it can effectively adjust the structure of rural planting industry.
Retting kenaf does not go into the water, and each acre of kenaf saves 0.2 acres of water surface. The 600,000 acres of water surface saved every year can be used to develop aquaculture, thereby creating more material wealth for farmers.