Materials which are made by combining two or more materials differing in composition or form.
Eco-friendly green composites, which may replace conventional manmade fibre-reinforced plastics, have been increasingly considered as promising materials due to their many advantages, like using a natural resource, environmental friendliness, sustainability, lightness, carbon dioxide reduction in nature, etc. Their unique balance of properties would open up new market development opportunities for bio-composites in the twenty-first–century’s, green materials world.
Composites are widely used in our day to day life due to their low weight and ability to be tailored for specific end use. They have gained a considerable ground in the high-performance applications, such as aerospace and automobile industry. However, the use of polymers that can be recycled when used with carbon and other niche fibres renders the composite non-recyclable. This has become a major issue as the landfills are filling up at a faster pace along with the need for going green due to global warming.
To tackle these issues research in recent years has been focused on substituting olefin (polypropylene, polyethylene, etc) based composites with biodegradable ones. Green composites are a specific class of biocomposites, where a bio-based polymer matrix is reinforced by natural fibres, and they represent an emerging area in polymer science. In order to achieve the goal of recyclable composites, natural fibres are surfaced as the fibres of choice for reinforcing composites. Bio-composites and green composites are being developed to address issues such as resource saving, lightweight, low cost, carbon neutral, and eco-friendly through stages of a product’s lifecycle.
Fast growing population, eco and health awareness create large space for future expansion of natural fibres. This can help to stop forests depletion, the flood of non-biodegradable wastes, environmental degradation, and also raise the living standards of rural areas in many parts of the globe.
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Introduction
Composites are biphase or multiphase materials which are made by combining two or more materials differing in composition or form. Due to their low weight and ability to be tailored for specific end use they have gained a considerable ground in high-performance applications. Biopolymers or synthetic polymers reinforced with natural fibres (Sisal, Jute, Silk, Coir, Bamboo, Arecanut and Pundi) frequently termed as “bio-composites” can be viable alternatives to glass fibre reinforced composites. “Green Composite” is a completely bio-based composite; both matrix and fibre are completely biodegradable and renewable.
Green-composites
Green composites are completely bio-based composites in which both matrix and fibre are completely biodegradable and renewable. Natural, vegetable fibres can be applied to reinforce the natural polymers such as starch, lignin, hemicellulose and India-rubber which results in 100% biodegradable material. Essentials for green composites are high strength natural fibres, resins with good bio-degradability and optimum fibre/resin interfacial bonding.
Composite properties depend on the properties of the constituents, i.e. the fibres and resins used. The strength and stiffness of the composites are directly a function of the reinforcing fibre properties which carry most of the load, and their volume content. The resin helps to maintain the relative position of the fibres within the composite and, more importantly, transfers the load from broken fibres to the intact fibres. As a result, fibre/resin interfacial properties are also important and have a significant effect on composite properties, including toughness and transverse fracture stress. In summary, to fabricate high strength composites all three factors, namely, fibre properties, resin properties as well as the fibre/resin interface characteristics are critical.
Reinforcing Biofibres
In biocomposites, the bio-fibres serve as a reinforcement by enhancing the strength and stiffness of the resulting composite structures. Sources, origin, nature, as well as the physical and chemical composition of different natural fibres, have been reviewed. The conventional fibres like glass, carbon, aramid, etc., can be produced with a definite range of properties, whereas the characteristic properties of natural fibres vary considerably. This depends on whether the fibres are taken from plant stem or leaves, the quality of the plants’ locations, the age of the plant and the preconditioning. Depending on their origin, the natural fibres may be grouped into leaf, bast, seed, and fruit origin.
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The natural fibres are lignocellulosic in nature. Lignocellulosic materials are the most abundant renewable biomaterial of photosynthesis on earth. In terms of mass units, the net primary production per year is estimated to be 2X1011 tons as compared to synthetic polymers by 1.5X108 tons. Lignocellulosic materials are widely distributed in the biosphere in the form of trees (wood), plants and crops. Cellulose, in its various forms, constitutes approximately half of all polymer utilized in the industry worldwide.
For more industry information, please pay attention to Knitting Fair.
Source: textile school
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The textile industry is considered as the most ecologically harmful industry in the world. The Eco-problems in textile industry occur during some production processes and are carried forward right to the finished product. In the production process like bleaching and then dyeing, the subsequent fabric makes a toxin that swells into our ecosystem.Therefore the need for eco-textiles is felt.Green textiles refer to clothing and other accessories that are designed to use the organic and recycled material.
What is Eco-Textiles?
In recent years ecological issues have loomed large especially in textile and apparel industry, an industry not noted for eco-friendliness.Every textile item releases effluents that are harmful to the environment.The traditional textile industry consumes large amounts of earth’s natural resources and pollutes the environment as their production and processing involve Chemical Intensive Applications, therefore, the need for green textiles. During the production process controlling pollution is as vital as making a product free from the toxic effect. The utilization of rayon for clothing has added to the fast depleting forests and opened the door to the development of natural sustainable fibers like Organic Cotton, Hemp, and Bamboo fibers. Petroleum-based products are harmful to the environment. In order to safeguard our environment from these effects, an integrated pollution control approach is needed.Fabrics made in an eco-friendly way can substitute normal products.Green textiles refer to clothing and other accessories that are designed to use organic and recycled materials, less packaging and more energy-efficient manufacturing.Reducing the environmental impact throughout the life-cycle of a fabric item or using lower impact products can contribute actively to improve the situation.In general, there are four major environmental key factors associated with the making of textiles: water, energy, pollution, and use of non-renewable resources.
Green Activities in Textile Industries
Textile and clothing manufacturers are encouraged to re-examine the whole life cycle of their products with the aim to minimize environmental degradation at every stage, from manufacturing to disposal. They have to pay special attention in the selection of dyes and ensure the products are low in formaldehyde and free from pesticides and heavy metals. The reason behind those environmental requirements in textile and garment are as follows:
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Human skin has a light acid coating which inhibits the development of many diseases, textiles in which the pH lies in the neutral(pH7) or slightly acid region(below 7)are friendly to the skin. Alos, under extreme pH conditions fabric will be damaged.
Easy care finishing incorporates artificial resin containing formaldehyde which is intended to prevent shrinkage and to give the product a crease- resistant, smooth dry and soil release finish. However, resin finished fabric may retain chlorine resulting in fishy odor, fabric damage, and skin irritations. Formaldehyde is found in clothing in a latent form as resin and also as free formaldehyde (split off from the resin by high temperature, pH or oxidants). Formaldehyde has a strong irritant effect on the mucous membrane and may cause inflammation of the human respiratory tract. It can also give rise to inflammation of the skin. Formaldehyde is one of the most significant allergy-causing agents and is probably also cancer inducing.
Pesticides are used in cotton cultivation for combating insects and also as moth protection during storage. They are rated from slightly to strongly toxic for humans. Sometimes they are very easily assimilated into the skin.Linden is a possible cause assumed to be cancer inducing.
To prevent mold spots(caused by fungi) chlorinated phenols are applied directly on the textiles and leather mainly in the third world countries. Both PCP and TCP are very toxic and regarded as cancer-inducing substances.
This is the name of the group of synthetic dyestuffs based on nitrogen and which are often used for textiles.Separation products of certain Azo dyestuffs are regarded as cancer-inducing and allergic. If a person has once been sensitized, other products which are containing Azo dyestuffs will lead to allergic reactions.
The presence of nickel in certain objects coming into direct and prolonged skin contact may cause sensitization of humans to nickel and may lead to allergic reactions.The use of nickel in such objects is thus limited. Such objects include rivet buttons, tighteners, rivets, zippers and metal marks when these are used in garments.
For more industry information, please pay attention to Knitting Fair.
Source: textile school
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