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Units manufacturing linen, hemp, kenaf and jute fibers

Units manufacturing linen, hemp, kenaf and jute fibers

Fibers derived from bio-based sources such as vegetables and animal origin are termed as natural fibers. This definition includes all natural cellulosic fibers cotton, jute, sisal, coir, flax, hemp, abaca, ramie, etc. There are also man-made cellulose fibers e. Natural fibers being cost effective and abundantly available yields high potential in various industrial and commercial applications such as in the interior applications of the passenger cars, panels for partition and false ceiling, partition boards, roof tiles, coir fibers in packaging, furniture applications, as insulating materials in low energy houses, geo-textiles for soil protection and erosion control, enhancing barrier properties, composites etc. Due to research and developmental work in modification and treatment methods of natural fibers, utilization of natural fibers has observed a significant growth in various applications. The chapter addresses the potential applications of natural fibers in various commercial sectors for the development of environment-friendly products with an aim to replace synthetic fibers or inorganic fillers with cost-effective and efficient products.

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Natural Fibers: Applications

Fibers derived from bio-based sources such as vegetables and animal origin are termed as natural fibers. This definition includes all natural cellulosic fibers cotton, jute, sisal, coir, flax, hemp, abaca, ramie, etc. There are also man-made cellulose fibers e. Natural fibers being cost effective and abundantly available yields high potential in various industrial and commercial applications such as in the interior applications of the passenger cars, panels for partition and false ceiling, partition boards, roof tiles, coir fibers in packaging, furniture applications, as insulating materials in low energy houses, geo-textiles for soil protection and erosion control, enhancing barrier properties, composites etc.

Due to research and developmental work in modification and treatment methods of natural fibers, utilization of natural fibers has observed a significant growth in various applications. The chapter addresses the potential applications of natural fibers in various commercial sectors for the development of environment-friendly products with an aim to replace synthetic fibers or inorganic fillers with cost-effective and efficient products. The transition toward a bio-based economy and sustainable developments as a consequence of the Kyoto protocols on greenhouse gas reduction and CO 2 neutral production offers high perspectives for natural fiber markets.

Changing to a bio-based economy requires substitution of common raw materials that are currently largely produced from fossil petrochemical or mineral resources, by-products produced from renewable plant and animal based resources [ 1 ]. The development of a sustainable global economy, which permits improving purchasing power and living standards without exhaustion of resources for future generations, requires a fundamental change in attitude.

On ecological grounds products should then be preferred that are based on photosynthetic CO2 fixation [ 1 ]. The benefit of those sustainable resources is that they can be regrown within the foreseeable future, without negative side effects on global biodiversity.

Therefore, competitive products based on renewable resources need to be developed to have high quality, show excellent technical performance, and harm the environment less than current products based on petrochemical materials [ 2 , 3 ]. Table 1 below shows the major natural fiber producers in the world, their potential applications and associated by products.

Natural fiber type, producers and markets [ 4 ]. In , global fiber production exceeded million mt resulting in the largest fiber production volume ever. Synthetic fibers have dominated the fiber market since the mids when they overtook cotton and became the dominant fiber. More than 53 million mt of polyester is produced annually. Cotton is the second most important fiber since synthetics took the lead in the mids [ 4 ].

An increasingly important fiber category is man-made cellulosics MMCs with a global production volume of around 6. The need to decouple growth from resource consumption gets more urgent every year. The significant growth in fiber production results in a significant use of natural resources and a huge production of textile waste.

There is a growing awareness of the urgent need for a more responsible use of resources, enabling growth without increased resource consumption. An innovation toward a circular economy and dematerialization can be seen in almost all fiber categories.

Accelerating such initiatives will help to reduce the overall fiber footprint on the planet [ 4 ]. Natural fibers have three main components lignin, cellulose and hemi-cellulose, percent of each vary with each type of natural fiber. Hemicellulose is strongly tied to cellulose fibrils presumably by hydrogen bonds.

Hemicellulose polymers are branched and fully amorphous and have a significantly lower molecular weight than cellulose. Because of its open structure containing many hydroxyl and acetyl groups, hemicellulose is partly soluble in water and hygroscopic.

Lignin is amorphous, highly complex, and mainly aromatic polymer of phenyl propane units but had the least water absorption of the natural fiber components. Amorphous lignin matrix helps in the combination of helically arranged cellulose microfibrils, which results in the formation of composite fiber. Lignin plays a very important role in the plant fiber such as water holding capacity, provide protection against biological attacks, and strengthened the stem against wind and gravity forces.

Hemicellulose found in the plant fibers is believed to be a compatibilizer between cellulose and lignin [ 5 ]. However, the quality of natural fibers is greatly influenced by various factors like the age of the plant, species, growing environment, harvesting, humidity, quality of soil, temperature, and processing steps, and there is a move to reduce the on-field processing to improve consistency and reduce costs [ 6 ].

For centuries different sources like wood, oil, coal and currently materials like coke, natural gas, nuclear materials etc. With the significant increase in population, civilization, and industrialization, the consumption of energy has increased many folds. There is a continuous search for sustainable development with minimum pollution and better efficiencies for reduction in energy consumption which have led to the development of wind energy.

It is a prominent renewable energy source available to mankind which can be part of the solution of the global energy problem [ 7 ]. Currently the wind energy sector is growing, and highly efficient systems capable for converting the kinetic energy of the wind into mechanical or electrical energy are available. Generally the wind turbines consist of three rotor blades that rotate around a horizontal hub and convert the wind energy into mechanical energy and are the key component of the wind turbine.

However the design aspect of these wind blades plays a major role in conversion process, the aerodynamic shape, the length of blades, and the material of construction used by the manufacturer. Based upon the design of orientation of the shaft and rotational axis, wind turbines can be classified into two types Figure 1.

A turbine with a shaft mounted horizontally parallel to the ground is known as a horizontal-axis wind turbine HAWT , and turbine with shaft normal to the ground is called vertical-axis wind turbine VAWT. Fiber-reinforced composite materials have been the choice for the commercial production of large-scale wind turbine rotor blades especially glass and carbon fibers.

Carbon fibers are preferred over glass fibers because they provide superior mechanical strength due to their lower density and higher fatigue ratio which extends the life of the blades.

The high cost of the carbon fibers which start with the expensive poly-acrylonitrile polymer PAN precursor and due to the environmental concerns and stringent laws, these are not considered as first choice since the commercial production of these types of fibers is highly dependent upon petroleum-based resources [ 11 ].

Because of these and similar reasons, researchers around the globe have shifted their focus on replacing these man-made fibers with natural fibers. Some of the main requirements for the wind turbine blade are a high strength, b high fatigue resistance and reliability, c low weight, and d high stiffness [ 12 ]. There is a huge potential to reduce the overall manufacturing cost of the wind turbine blades and replace the man-made fibers with natural fiber-reinforced composite materials.

Balsa, flax, hemp, coir, abaca, alpaca, bamboo, and jute fibers have been marketed as potential and prospective substitutes to the traditional composite reinforcements. Lignin which is an aromatic biopolymer and abundantly available and can be sourced from plants and wood can be used as a precursor for production of carbon fibers. Generally wind turbine blades are made up of array of sandwich panel strips and panels. Because of its light in weight and stiffness relative to density, balsa wood is being studied and used for making wind turbine interior panels and sandwich components [ 11 , 12 ].

The performance of NFC-based wind turbine blades depend upon the following factors [ 10 ]: Matrix selection—Matrix plays an important role in fiber-reinforced composites. It acts as a barrier against environment and protects the surface exposed from mechanical abrasion.

Most commonly used matrices are polymeric in nature as they hold certain advantages being light in weight and easy to fabricate, can be designed to withstand harsh temperatures, etc.

Thermoplastic e. Fiber selection—All the plant-based fibers hold cellulose as the major structural component. Choice of the fiber depends upon the country or region and size of the wind turbine blade. It is important to know the availability of the fiber since it varies from country to country.

The size of the blade governs the nature of mechanical performance requirements; therefore one particular fiber might not provide adequate strength for a particular size blade. Generally better performance can be achieved with fibers having higher cellulose content and cellulose microfibrils aligned more in fiber direction. Typical examples are flax, hemp, kenaf, jute, and ramie fibers.

The properties of the natural fibers do vary depending upon the chemical structure and composition, growing conditions, treatment procedures, harvesting time, extraction method, and storage procedures [ 14 ].

Some alignment can be achieved during injection molding process and manual placement of long fibers [ 15 , 16 , 17 , 18 ]. Interference strength—Though the natural fibers are obtained from renewable resources and the composite materials will be environment-friendly, there are certain disadvantages also associated with unmodified or raw natural fibers.

Some of the major problems can be high moisture uptake, low thermal stability, poor adhesion, poor mechanicals, etc. Hydrogels are polymers having a three-dimensional cross-linked hydrophilic structure produced by simple reaction of one or more monomers which renders them capability of absorbing, storing, and releasing water molecules.

Hydrogels have been researched considerably over the past decades due to their promising application in various fields. Some of the application areas of hydrogels include the manufacture of personal hygiene products, medical devices, environmental, agricultural, drug delivery systems, pharmaceuticals, biomedical, tissue engineering and regenerative medicines, wound dressing, biosensor, separation of biomolecules or cells and barrier materials to regulate biological adhesions, etc.

Hydrogels can be classified based upon the following [ 22 ]: Source—Based upon the source, hydrogels can be categorized into two groups: natural and synthetic.

According to the polymeric composition—Preparation method leads to different class of hydrogels. Cross-linking will depend upon the nature of monomer and polymerization technique. In semi-IPN hydrogel, one is cross-linked, while the other component is non-cross-linked. Type of cross linking—Based upon the chemical or nature of cross-linking junctions, hydrogels can be classified into two categories. Chemical cross-linked having permanent junctions and hydrogels with physical networks arising from physical entanglements or interactions [ 27 ].

Configuration—Based upon the chemical composition and physical structure, the hydrogels can be amorphous, semicrystalline, and crystalline. Physical appearance—It is governed by the polymerization technique used for preparation. Hydrogels can be in form of matrix, films, microsphere, etc. Network electrical charge—On the basis of the presence or absence of electrical charge located on the cross-linked chains, hydrogels are divided into four groups: nonionic, ionic, amphoteric, and zwitterionic polybetaines electrolytes.

Lignin, hemicellulose, and cellulose are the major constituents of natural fibers. Lignin which coats or covers the cellulose part shows lower tendency to react with other molecules and poor adhesion with polymer matrix.

Therefore the natural fibers most of the time have to undergo through treatment or modifications to improve the reactivity, interaction, and better adhesion with polymer matrix or other molecules [ 28 ].

For the hydrogel production, the natural fibers are modified in two stages: Pretreatment step—It is a very common step even used when NF are used in composite material production also. The main objective of this step is the removal of lignin which is nonreactive toward other molecules and is achieved by alkaline treatment [ 29 ].

Chemical modification—The step involves insertion of molecules into active sites of natural fibers of cellulose [ 30 ]. Collectively these steps increase the water absorption and retention capacity throughout with the help of modifying agents and active site generation.

Hydrogel synthesis methods are mass polymerization, solution, and reverse suspension use of initiator and a crosslinking agent. Generally hydrogel synthesis based upon the plant fibers uses solution polymerization method [ 28 ]. Figure 2 shows general hydrogel preparation process. Table 2 shows the different polymerization techniques, method employed, and type of characterization required during hydrogel synthesis. Solution polymerization is typically the preferred method for synthesis.

In acidic environment, hydronium ions interacts with hydroxyl groups of cellulose to form hydrogen linking forces resulting in increasing chain cross-linking and decreasing absorption capacity, whereas in basic media due to the neutralization of active sites, the swelling ability decreased. The effect of use of natural fibers at nanoscale level in the hydrogels also has been studied, and few of the advantages found are the following: Better mechanical strength of hydrogels. Hydrogels can be tailored and designed as per the requirements and needs for different applications.

Natural fibers as part of hydrogels synthesis can provide an eco-friendly alternative and fulfill the potential. Automotive manufacturers and associations are under tremendous pressure to improve on fuel efficiency and lower emissions.

One of the best ways is to reduce the overall weight of the vehicle which can be possible in replacing metal with lightweight composite materials [ 43 ].

Automakers have taken initiatives to design and utilize natural renewable resources as part of composite materials, though the use of natural biomaterials like natural fibers in automotive dates back to s when Henry Ford produced the first composite component using hemp fiber.

Similarly many other automotive manufacturers started following the same path down the line.

An understanding of friction and wear behavior of materials is crucial in order to improve their performance and durability. New research is providing the opportunity to solve common problems relating to the development of materials, surface modification, coatings, and processing methods across industries. Processing Techniques and Tribological Behavior of Composite Materials provides relevant theoretical frameworks and the latest empirical research findings on the strategic role of composite tribology in a variety of settings.

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Это невозможно. Хейл высокомерно засмеялся. - Одна из проблем, связанных с приемом на работу самых лучших специалистов, коммандер, состоит в том, что иной раз они оказываются умнее. - Молодой человек, - вскипел Стратмор, - я не знаю, откуда вы черпаете свою информацию, но вы переступили все допустимые границы.

Вы сейчас же отпустите мисс Флетчер, или я вызову службу безопасности и засажу вас в тюрьму до конца ваших дней.

О Боже! - воскликнул.  - Что случилось. ГЛАВА 93 Причастие. Халохот сразу же увидел Беккера: нельзя было не заметить пиджак защитного цвета да еще с кровавым пятном на боку.

Светлый силуэт двигался по центральному проходу среди моря черных одежд. Он не должен знать, что я.  - Халохот улыбнулся.

Открыв ее, она увидела несколько дополнительных папок; создавалось впечатление, что у Хейла было множество почтовых адресов. Один из них, к ее удивлению, был адресом анонимного провайдера. Сьюзан открыла одно из старых входящих сообщений, и у нее тотчас же перехватило дыхание. ТО: NDAKOTAARA.

У тебя ужасный вид.

Я так хочу выбраться отсюда. Беккер легонько обнял. Девушка высвободилась из его рук, и тут он снова увидел ее локоть. Она проследила за его взглядом, прикованным к синеватой сыпи.

Подняв глаза, он увидел старика с усыпанным родинками лицом, который стоял перед ним, намереваясь пройти. Беккера охватила паника.

Он уже хочет уйти. Выходит, мне придется встать.

Ну только подумайте. Усадить человека моих лет на мотоцикл. Просто позор. - Могу я для вас что-нибудь сделать. Клушар задумался, польщенный оказанным вниманием. - Если честно… - Он вытянул шею и подвигал головой влево и вправо.

Халохот замедлил шаги. Мгновение спустя появились еще двое - тучный мужчина и рыжеволосая женщина. Они также подошли к Танкадо. - Неудачный выбор места, - прокомментировал Смит.  - Халохот думал, что поблизости никого.

Халохот какое-то время наблюдал за происходящим, потом скрылся за деревьями, по-видимому, выжидая. - Сейчас произойдет передача, - предупредил Смит.

Common examples include cotton, linen, jute, flax, ramie, sisal and hemp. used natural fibers are cotton, flax and hemp, although sisal, jute, kenaf and coir workers in fiber processing, spinning of coir yarn and manufacture of coir fabrics. while their enzyme systems hydrolyze these polymers into digestible units.

Он впутал в это дело Сьюзан и должен ее вызволить. Голос его прозвучал, как всегда, твердо: - А как же мой план с Цифровой крепостью. Хейл засмеялся: - Можете пристраивать к ней черный ход - я слова не скажу.

- Ты уже задавал мне этот вопрос, помнишь. Пять месяцев. Я сказала .

Внизу что-то щелкнуло. Затем он снял наружную защелку в форме бабочки, снова огляделся вокруг и потянул дверцу на. Она была небольшой, приблизительно, наверное, метр на метр, но очень тяжелой. Когда люк открылся, Чатрукьян невольно отпрянул.

Ничего себе маленькая шишка, - подумал Беккер, вспомнив слова лейтенанта.

- Я там. У него случился инфаркт. Я сам. Никакой крови. Никакой пули.

У них состоялся откровенный разговор о его происхождении, о потенциальной враждебности, какую он мог испытывать к Соединенным Штатам, о его планах на будущее. Танкадо прошел проверку на полиграф-машине и пережил пять недель интенсивного психологического тестирования. И с успехом его выдержал. Ненависть в его сердце уступила место преданности Будде. Еще через четыре месяца Энсей Танкадо приступил к работе в Отделении криптографии Агентства национальной безопасности США.

Несмотря на солидный заработок, Танкадо ездил на службу на стареньком мопеде и обедал в одиночестве за своим рабочим столом, вместо того чтобы вместе с сослуживцами поглощать котлеты из телятины и луковый суп с картофелем - фирменные блюда местной столовой. Энсей пользовался всеобщим уважением, работал творчески, с блеском, что дано немногим.

Выбегая из собора в маленький дворик, он зацепился пиджаком за дверь, и плотная ткань резко заставила его остановиться, не сразу разорвавшись. Он потерял равновесие, шатаясь, выскочил на слепящее солнце и прямо перед собой увидел лестницу.

Перепрыгнув через веревку, он побежал по ступенькам, слишком поздно сообразив, куда ведет эта лестница.

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  1. Votilar

    Your idea is brilliant