Natural Fiber Based Composite Materials

Composite Materials: A composite material can be defined as a combination of two or more materials that results in better properties than those of the individual components used alone. The two constituents of a composite are a reinforcement and a matrix.​
Matrix: The continuous phase is the matrix, made of polymer, metal, or ceramic.​
Reinforcement: A strong, inert, woven and nonwoven fibrous material incorporated into the matrix to improve its mechanical and physical properties. For example, fibers, whiskers, particulate etc.​

1. Composite Materials ME 434 SRINJOY DE JOARDAR MEB18040 DEPARTMENT OF MECHANIACAL ENGINEERING TEZPUR UNIVERSITY

2. Natural Fibre based Composite Materials

3. Composite Materials : A composite material can be defined as a combination of two or more materials that results in better properties than those of the individual components used alone. The two constituents of a composite are a reinforcement and a matrix . Matrix: The continuous phase is the matrix, made of polymer, metal, or ceramic. Reinforcement: A strong, inert, woven and nonwoven fibrous material incorporated into the matrix to improve its mechanical and physical properties. For example, fibres, whiskers, particulate etc. COMPOSITE MATERIALS

4. A fibre has a length that is much greater than its diameter (high l/d ratio) They effectively transfer strength to the matrix influencing and enhancing composite properties as desired FIBRES

5. NATURAL FIBRES

6. NATURAL FIBRES

7. ADVANTAGES OF USING NATURAL FIBRE Obtained from Renewable Sources Requires little energy during production Recyclable Environmentally friendly during stages of production, processing and waste disposal Light Weight Producible with low investment at low cost Acceptable Specific Strength Properties Better Wear Protection Good thermal and acoustic insulating properties

8. DISADVANTAGES OF USING NATURAL FIBRE Moisture absorption , which causes swelling of the fibres. These are UV-sensitive . Lower durability . Low impact strength . Fibre degradation during processing.

9. S ome Natural Fibres and their Applications in Composites 1. Flax 2. Hemp 3. Jute 4. Coir 5. Asbestos

10. FLAX 1 Flax is an annual crop for multipurpose use: fibre and oil production, non-textile applications like in composites. The relevant part for fibre production is the stem . The stem has a length which goes from 600 to 1000 mm. For composite use, the length of 10 to 20 mm is sufficient. For the industrial use, the non-retted stems are dominantly mechanically decorticated.

11. Properties: Flax fibre is an ecologically safe alternative to reinforcing fibres in plastic composites. Flax fibres are less dense than glass fibres, are renewable and combustible , and they are less expensive. Strength and toughness of flax fibre are comparable to those of glass fibres. Applications: In 1941, flax and hemp fibres were used in resin matrix composites for the bodywork of a Henry Ford car which was claimed to have an “impact strength 10 times greater than steel”. These are typically combined with polypropylene, polyester, or polyurethane to produce components like door and trunk liners, parcel shelves, seat backs, interior sunroof shields, and headrests . Recently, flax has also been employed lo reinforce thermosetting resin (i.e., epoxy) in order to realize structural components for automotive and marine ships with high performances.

12. HEMP 2 Hemp is an annual plant native of Central Asia. True hemp is a fine, light-colored, lustrous and strong bast fibre obtained from retting. Color and cleanliness may vary considerably according to the method of preparation of the fibre. The lower grades are dark cream and contain much non-fibrous matter. The fibre ranges in length from 1.0 to 2.5 m.

13. Properties: Although acceptable composite properties have been obtained from mechanically extracted fibre, concern arouses over long-term stability due to degradation of Lignin , which mainly acts as an adhesive holding the cellulose fibres together. Removal of lignin, pectin and hemicellulos by means of alkali treatment improve instantaneous fibre properties due to better packing and increased molecular orientat ion of cellulose chains. However, over-treatment with alkali reduces fibre properties. Therefore, in order to optimize composite strength, it is important to be able to assess the effect of fibre extraction as well as growing conditions on fibre properties, particularly fibre strength. Applications: Hemp, is amongst the natural fibres now finding use in thermoplastic matrix composites for internal structures in automotive applications to those for flax fibres.

14. JUTE 3 White jute and dark jute fibres are obtained from the bast layer of the plants. Jute is the second most common natural fibre after cotton.

15. Properties: The jute fibre has prominent stiffness and hardness properties. Applications: It is widely used for the manufacture of flexible fabrics , its prospective use as carpet backing etc. Jute-based thermoplastic matrix composites find a substantial market in the German automotive door-panel industry . The fibre is used in marine industry to reinforce polyester resin.

16. COIR 4 Plantation of coconut are spread all over the world. Growing attention is being paid to coconut fibre. These fibres are extracted from the external layer of the exocarp and from the endocarp of the fruit. The coconut palm can be regarded as an integral part, such as leaf sheath, the bark of the petiole or from the midribs of the leaves.

17. Properties: Coir is inexpensive if compared to other natural fibres. Furthermore, it has advantages of lignocellulosic fibre. It is not brittle as glass fibres, is amenable to chemical modification, is non-toxic and poses no waste disposal problems . Unfortunately, the performance of coir as a reinforcement in polymer composites is unsatisfactory. The inferior performance of coir is due to various factors such as its low cellulose content, high lignin and hemicellulose content, high microfibrillar angle and large and variable diameter. Applications: Fibres extracted from the husk the nut, known as coir fibre, are now being commercially used, blended with natural rubber latex in the production of seat cushion parts in automobiles .

18. ASBESTOS 5 Asbestos is a naturally occurring mineral . They 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.

19. Properties: These are inflammable, have high tensile strength and are flexible . These are Insoluble in water; their colors depend on the types and the composition of the asbestos which is depends on the amount of iron. The mechanical properties depend on 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 ), the percentage of fibre mass fraction. The increase in the volume of fibre, increase the impact resistance of the polymer Hatschek process is the most widely used processing technique for asbestos fibre. Applications: Asbestos fibre is used in making fireproof materials and also insulation products (thermal and electrical). These are widely used for the fabrication of papers and felts for flooring and roofing products . These are also used to develop products for the automotive, electronic, and printing industries, insulating pipe insulating board roofing

20. Properties of Natural Fibre based Composite Materials

21. Mechanical Properties: Mechanical efficiency is dependent upon the interface provided by fibre-matrix along with the stress transfer function in which stress is transferred to fibre from matrix. Stiffness and stress transfer in composites increases with an increased or excessive addition of fibre The fracture behavior of composites is also affected due to the nonlinear mechanical behavior of natural fibres. To develop composites with good mechanical properties, chemical modification of fibre carried out to reduce the hydrophilic behavior of fibres and the absorption of moisture. Flame Retardant Properties: Natural fibres and polymers are organic materials and are very sensitive to alter any features if flame is introduced to them. Flame retardancy is a safety aspect to counter this.

22. Biodegradability: At high temperatures, natural fibres start degrading whereas constituents of fibre may start decomposing at earlier temperatures. The thermal stability can be improved if the concentration levels or the structural constituents are completely removed by chemical treatments. Natural fibres have a short lifetime with minimum environmental damage upon degradation whereas synthetic ones affect environment due to pollution caused by degradation. Energy Absorptions: High strength, energy absorption, and stiffness are obtained by composite materials which are widely used in automotive and motorsport sectors of industry mainly due to the property of mass reduction. Enhanced energy absorption is evident from the increased volume fraction that is only possible in the presence of low speed. On the other hand, at high speeds, similar performance is shown by flax, jute, and hemp.

23. Water Absorbent Properties: The main weakness of the application of natural fibres is their susceptibility to moisture. The natural fibres are rich of components which are hydrophilic sources and strong polar while the polymers show hydrophobicity. These can cause warping, buckling, bigger possibility of their microbial inhabitation, freeze, and unfreeze caused destruction of mechanical characteristics of composite materials. The effect of coupling agent such as maleic anhydride polyethylene and chemical treatments such as bleaching, acetylation, and alkali treatment reduces moisture absorption of natura fibre-based composites. Thermal Properties: Enzymatic treatment for many natural fibres such as flax and hemp often can lead to improvement in surface and thermal properties.

24. Industrial Applications of Natural Fibre based Composite Materials

25. AUTOMOTIVE INDUSTRY The automotive industry has developed various new components based on natural fibre composites. Only non-structural or semi-structural components are realized by mainly using polyester resin or thermoplastic polymers and lignocellulosic fibres (i.e., flax, hemp, sisal and jute). Bast fibre composites are predominantly used in automotive interior panels , such as doors, pillar, trim, trunk liners and package or real parcel trays. Flax or sisal material can be molded in complicated 3D shapes, thus making it more suitable for door trim panels than the previously used materials.

26. Natural Fibre based Composites in Mercedes C Class

27. AUTOMOTIVE INDUSTRY Natural fibres are broadly used for thermo-acoustic insulation . Such insulating materials, mainly based on cotton fibres recycled from textiles, have relatively high fibre content, more than 80 percent by weight. Another well established field of application is the use of coconut fibres bonded with natural latex for seat cushions . The most important structural application of natural fibre composites in automotive field are the load floors of several sport utility vehicles (example: Volkswagen Touareg , Porsche Cayenne and Audi Q7). These parts are a sandwich of expanded polypropylene foam covered on each side with fibre-polypropylene composites, and topped with PET carpet. Each load floor is produced in a single molding cycle.

28. BIOMEDICAL INDUSTRY The most important requirements for use in medical industry are biocompatibility and absence of adverse effect to the host tissues. The traditional structures began to be substituted by bio-engineered composites, consisting of biodegradable polymer as matrix and usually bio-fibres as reinforcing elements which have generally low cost, low density, high toughness, acceptable specific strength properties, good thermal properties, ease of separation, enhanced energy recovery and biodegradability. Silk fibre has been used in biomedical applications such as sutures by which the silk fibroin fibre is usually coated with waxes or silicone to enhance material properties and reduce fraying. Chicken feather fibre (CFF) has attracted much attention to different product design and engineering industries.

29. NAUTICAL INDUSTRY Due to their total biodegradability, bio-composites represent a valid alternative to glass fibres reinforced thermoset composites also in marine applications. The main disadvantage that limits their use in this field consists in a low durability in a seawater environment due to their hydrophilic nature. Bamboo is a natural material that offers good potential for composites as a substitute of solid wood for structural uses also in marine applications. Flax fibres can be used as reinforcement to realize nautical components like surf boards, rudders or thin keel.

30. OTHER APPLICATIONS Printed Circuit Boards (PCBs): Due to their total biodegradability, natural fibres represent an optimal alternative to materials currently used in PCBs (fiberglass and brominated flame retardants) as both of them will reduce health risks during manufacturing and at the end of their useful life. Research of bio-epoxy-flax PCB composite design gave acceptable results for thermal, mechanical and electrical properties with the exception of wet conditioning which can be improved by treating the flax fibres with sodium hydroxide and octadecyl trichlorosilane. Packing Industry: Another possible application of bio-composites regards the packing industry. Most plastic products are discarded after single use. Coconut or coir fibre can be used for packaging applications.

31. OTHER APPLICATIONS Electronic Application: Chicken feather fibres can be used as reinforcements in composites for electronic application (as high-speed data transforming insulator material). It has been found that the dielectric properties of chicken feather fibrils using epoxy resin as matrix are dependent on operating frequency and temperature conditions and such composites have potential use as low as dielectric materials. Civil Application: The natural fibres are also used to realize element for insulating in order to reduce the thermal conductivity of the walls. They are generally mixed with polymeric or ceramic matrices.

32. CONCLUSION Natural fibres-based composites are an effective way of improving the quality of parts regarding the environment, economic and technical and mechanical feasibility. These have beneficial properties such as low density, less expensive, and reduced solidity when compared to synthetic composite products. However, to accomplish this goal, there are certain issues that need to be tackled, some of them being related to the properties of the natural fibre. Despite these backdrops, natural fibre-based composites have paved its way to extensive usage in various commercial sectors, such as automotive industry, biomedical industry, buildings and construction etc.

33. THANK YOU! Srinjoy De Joardar MEB18040 Department of Mechanical Engineering Tezpur University