• Composites = combinations of two or more materials. - which is reinforcing phase (fibre) and matrix phase Fibre reinforced polymer Matrix phase – polymer Fibre as reinforcing phase - act as a binder and a - to enhance the strength and medium to tranfer stresses elasticity of plastic. between reinforcing fibers.
Types of polymer matrices Thermoplastic Thermoset - materials that undergo a chemical reaction - Above its melt point, the plastic liquefies (curing) and transform from a liquid to a solid. (softens enough to be processed). - The cross link between their uncured form (in This process can be repeated, with the plastic monomer form) and the catalyst that initiatemelting and solidifying as the temperature climbs the chemical reaction is irreversible. above and drops below the melt temperature respectively - The exposure to high heat will cause the material to degrade, not melt. The advantage of thermoplastics over thermosets are thermoplastics has higher elongation at break. Thus, it is necessary in order to improve impact strength.
renewable source, requires little energy during Producible with low production and use carbon investment at low cost dioxide while oxygen is given back to the environment. Advantages of natural fibre composites They are environmentally friendly materials at the Good thermal and acoustic stage of insulating propertiesproduction, processing and waste.
one of the type of natural fiber that consist of cellulose, hemi- cellulose, lignin, pectin.Properties of the plant fibers.• The fibers are normally a rigid, crystalline cellulose micro fibril-reinforced amorphous lignin and with hemicellulosic matrix.• Mechanical structural of plant fibers is much lower when compared to reinforcing glass fiber.• Somehow, because of the low density, their properties for such the strength and the stiffness of the plant fibers are comparable to the values of glass fibres. (the detail will be disscussed further in the part 2)
- Generally compromise of proteins Animal Hair - wool, humanClassification of hair, feather animal fibre Silk fibre
Example - Wool Properties of wool• low tenacity because it has excellent elongation and elastic recovery• durable with moderate resistance and it is also poor conductor of heat• very sensitive to some alkalis• give influence on the tensile stress or modulus of elasticity with increasing fraction of wool content• when arranged in a transverse position to the tensile load, the tensile stress was increased• may be able to provide reinforcement in multi-axial situations.Properties of wool fibre composite• Effect of orientation of fibre - transverse position increase the tensile stress and toughness. - The modulus of elasticity does not effected fibre samples.
Processing and extraction of wool fibre Shearing SORTING CLEANING CARDING SPINNING WEAVING FINISHING• As a composite, wool fibres have been combined with polyester fibres and spun into multistrand yarn as threads• Traditionally, wool fibres have been spun into multilayer fibres in the form of threads, then knitted into cloth and utilized for the manufacture of garments• The composite matrix was prepared from polyester resin with 1% hardener (methyl ethyl ketone peroxide).• Samples of composite sheets were prepared in the laboratory from skeins of wool laid alternatively with layers of resin mixture, and placed in a rectangular mould.
Application of wool fiber• used as alternatives for producing composite materials which may have great scope in value added application including bio- engineering and medical applications• In the textile industries, a lot of waste wool fibers and their products induce actions which lead to the regeneration of wool keratin materials• Animal fiber reinforced composite - applications in the automotive, aerospace and sports equipment industries• Advantage of animal fiber composite materials is that they can be tailored to meet the specific structure such as face brush makeup, blanket etc.
• the only naturally occurring of mineral fibre – asbestos• Asbestos fibres are silicate compound which contain silicon and oxygen in their molecular structure.• The crystal in these fibres forms a long, thin and flexible fibre when separated. This is a piece of asbestos Asbestos fibers as seen rock. Can you see the through a microscope fibers?
Properties of asbestos fibre• Resistance to fire or inflammable• Poor thermal and heat conductor• High tensile strength and flexible• Insoluble in water• their colours depend on the types and the composition of the asbestos which is depends on the amount of iron. Properties of asbestos fibre composite• The mechanical properties depends on; i) The orientation of the fibre In axial orientation, the composite shows the higher tensile strength while in radial orientation, the composite shows the higher compressive strength(Lee & Kim, 2004). ii) The percentage of fibre mass fraction The increase in the volume of fibre, increase the impact resistance of the polymer(Akens & Garret, 1986)
Processing and extraction of asbestos fibre 1st step - Mining process – open-pit mining extracts the rock or minerals from the earth by remove it from an open pit or borrow. 2nd step - Milling process - extraction of the fibre from the ore - separation and degradation of fibre according to its lenght Dry milling Wet millingthe fibre extraction were done by crushing the asbestos is dispersed through the water the ore using different series of crushing and not being dried until the separationmachine and pass to vacuum aspiration on a process of fibre was completed vibrating screen
Processing of asbestos fibre composite.Most widely method - Hatschek process (or wet process)- This process produce the fibre cement sheets by stacking together the thinlamina which is made from a suspension (slurry) of cement, fibre, limestonefiller and water Schematic diagram of a typical Hatschek process, where are slurry (1),Cement (2), asbestos (3), limestone filler (4) ,water (5) , vats (6), sieve cylinders (7), running felt (8), Vacuum (9), formation cylinder (10), Green lamina produced (F) cutting of the green lamina (11), moulding (12) , finish product (P)
Application of asbestos fibre• Used in making fireproof materials and also insulation products (thermal and electrical)• Widely used for the fabrication of papers and felts for flooring and roofing products.• Develop products for the automotive, electronic, and printing industries. insulating pipe Insulating board roofing
Problems of asbestos fibre• Unfortunately, asbestos can cause health effects when the fibres are breath into the lungs or being swallowed into the body and eventually accumulate in the bodies and lodged in tissues.• This can lead to the lung cancer, mesothelioma (a cancer of the linings around the lungs and abdomen), asbestosis (scarring of lung tissue that impairs in breathing) and eventually can lead to the death.• But the low levels exposure of asbestos can’t be harmful to human body.• Thus, precaution steps must be taken when handling this fibre.
Some of the precaution steps.• Wear coveralls and an approved respirator• Do not use abrasive cutters and sanders on asbestos cement products.• Wet down material to reduce the release of dust• Work in well ventilated areas where possible• Immediately dispose of smaller asbestos pieces and collected dust in plastic bags, which are clearly labelled asbestos waste.
STEM FIBRE Example – Jute fibre• This fiber are extracted from the ribbon of the stem.• Use retting process in extracting this this kind of fiber from the long lasting life stem or the bast.• give more application toward strength, lightweight and noise absorption.
Properties of Jute fibre• favor moderately high specific strength and stiffness• cheap with high performance composite• easy availability, low cost, high strength (tensile strength).• developed with different thermoplastic andthermoset polymers such as jute reinforcepolyester, epoxy composite and jute reinforcedpolypylene.
Propertis of Jute-polyester Composite• High in mechanical properties• The percentage of fibre volume affetcs the composite mechanical properties such as tensile, strain, toughness and moduli.
Processing and extraction of jute fibre• The process - retting process• To extract fine fibers from jute plant, - the first parameter were considered is if the fiber can be easily removed from the jute hurd or core before the crop been harvested.• Jute stalk after harvesting are submerged in soft running water in bundles in 20 days.• then, grabbed in bundles and hit with a long wooden hammer to make the fiber loose from the jute hurd or core.• Then, the extracted jute fiber is washed with water and left to dry.
Application• Give advance in strength, lightweight and noise absorption• commercially important in the automotive and building industry, i.e roofing.• As decorative, vast, in sacking, yarn and carpet backing, all now replaced by synthetic fibres.
FRUIT FIBRE Example – Banana fibre• Banana fibers obtained from the stem of banana plant (Musa sapientum) present important advantages such as low density, appropriate stiffness and mechanical properties and high disposability and renewability• Banana fiber was used because of its ability to be produced in a continuous form, and hence able to be produce into woven mat form
Properties of banana fibre• chemical composition are cellulose, hemicellulose andlignin• is better in terms of fineness and spinnability whichinclude ring spinning, open-end spinning, bast fiberspinning and semi-worsted spinning.• highly strong fiber, has smaller elongation and itsweight is light.• it has strong moisture absorption quality• can be categorized as eco-friendly fiber because it isbio-degradable and has no negative effect onenvironment
Properties of banana-polyester composite• the percentage volume fractions of banana fibre effects the tensile strength. - The results shows that an increasing of percentage volume fractions of banana fibre increase the the tensile modulus of the composite. - While, for the tensile strength, only after 0.1% volume fraction of the fibre, the tensile strength increase gradually.
Processing and extraction of banana fibreJapanese Nepalese method method
Japanese method• In the Japanese method of making banana fiber, the care is taken as early from the plant cultivation stage• To ensure their softness, the leaves and shoots of the banana plant are pruned periodically.• harvested shoots are first boiled in lye to prepare the fibers for making the yarn, whereas at the same time the banana shoots give away fibers having varying degrees of softness.• As a results, different qualities of yarns and textiles produced that can be used for specific purposes.
different qualities of yarns and textiles produced that can be used for specific purposes The outermost fibers of the shoots are While the innermost part of banana fiberthe coarsest ones and more suitable for is the softest and widely used for making making such home furnishing as kimono and kamishimo, the traditional tablecloth. Japanese apparels.
Nepalese method• Second method is Nepalese method in which the trunk of the banana plant is harvested instead of the shoots.• The steps 1) small pieces of these trunks are put through a softening process for mechanical extraction of the fibers, bleaching and then drying to produce fiber that has appearance similar to silk. - During the processed, only the aged bark or the decaying outer layers of the banana plant are harvested and soaked in water to quicken the natural process. 2) After that, when all the chlorophyll is dissolved and only cellulose fibers remain, they are extruded into pulp so that they may become suitable for spinning into yarn. 3) The yarn is then hand-dyed and these rugs are woven by hand –knotted methods again by the women of Nepal.
Applications of banana fibre• The application of banana fiber only limited for making items like ropes, mats and some other composite materials• home furnishings.• used to make fine cushion covers, necties, bags, table cloths, curtains• due to its being lightweight and comfortable to wear, Japan people also preferred to use kimono and kamishimo as summer wear.
The processing of the plant fibres composite.• Hand lay up process: The fibres are manually placed into a one- sided gel coated male or female mould A matrix of thermosetting resin is rolled onto the fibres using an hand roller More layers can be added and, after drying, the composite part can be removed from the mould.
• Compression moulding process:The mould is closed and pressure is then applied to force the material to fill up the entire mold cavityExcess material is channelled away by the overflow grooves The heat and pressure are maintained until the plastic material is cured
• Nowadays, natural fiber has been used in industries and manufacturing company for its enormous potential for application in different engineering utility.• It is widely used due to their several advantages which are cost effective, renewable material and also environment friendly.• There are three types of natural fibers which are plant fibers, animal fibers and mineral fibers. Among them, plant fibers are used much higher compare to others because of its renewability, recyclability, availability and environmental friendly. For mineral fiber, asbestos is less used or prohibited in certain country because of carcinogenic mineral.• By using natural fiber composites, they would be sustainable and biodegradable. Thus, it is good in other to save our environment.
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