(+91) 9686 448899
Kruger Industries E 42 & 43 2nd Main 2nd Phase, Peenya Ind Area, Bengaluru - 560058, India
(+91) 9686 448899
Kruger Industries E 42 & 43 2nd Main 2nd Phase, Peenya Ind Area, Bengaluru - 560058, India
A composite is a material made from at least two or more materials with significantly different chemical and physical properties. When combined, they form another material that has properties different from the individual components.
Components are made of two parts: a fibre and a matrix. Fibres can be materials such as polyethylene, glass, carbon fibre, or Kevlar. At the same time, a matrix is what holds the fibres together.
The matrix is usually a thermoset such as an epoxy resin, polydicyclopentadiene, or polyimide. To make the material of the matrix stronger, the fibres are embedded into the matrix. This is one of the most common types of composite materials, called fibre-reinforced composites.
These days, polymer composites have found applications in various fields. They’re physical, chemical, and mechanical properties are what sets them apart from other metals.
Factors that decide the performance of polymer composites
And the geometry and the orientation of the fibre materials inside the polymer composite.
The performance of the polymer composites is usually called the mechanical properties of the composite materials. The mechanical properties are the most important physical and chemical properties.
Factors that influence the mechanical properties of composites:
The factors that influence the mechanical properties of the composites are given below:
Polymer Composites are classified at two distinct levels:
The first level of classification: This is made according to the polymer matrix constituents. The major component classes under this type of classification include:
The second level of classification: This is made according to the reinforcement form. These are further divided into:
Metal matrix composites (M.M.C.’s) are some materials (such as alloys, metallic, and intermetallic compounds) incorporated with reinforcing phases such as whiskers, particulates, or continuous fibers.
According to the matrix material, they are classified into the following metal matrix configurations:
The Aluminum-based matrix composites are widely seen in the aerospace and automotive industries. Fiber-based titanium composites are used in developing the structures of the aircraft. Titanium-based composites are used for manufacturing missile and aircraft structures, whose operating speeds are very high.
The main disadvantage of titanium-based composites is that they are highly reactive. Magnesium–matrix composites have lower thermal conductivity and are used actively in the space industry. Superalloys are commonly used for the manufacture of turbine blades as they operate at higher speeds and temperatures.
These polymer matrix composites are the most produced composite matrix materials. The fibers in Polymer Matrix Composites (P.M.C.’s) are embedded in the organic polymer matrix. This kind of polymer is used to enhance the properties of the materials.
These types of polymer composites are present in almost every aspect of life. Its applications range from gadget components to automotive accessories. The most common type of polymers that are used as composites is either elastomers, thermosetting polymers, or thermoplastic polymers. The many added advantages of the Polymer matrix composites (P.M.C.’s) include:
Properties of Polymer matrix composites (P.M.C.’s)
The overall properties of a P.M.C. are affected by its constituents; these are:
The two distinct types of categories include:
The detailed classification of polymer matrix composites is as follows:
The Glass Fiber Reinforced polymer composite is produced in the largest quantities. GFRP composite or FRP composite consists of glass fibers in the polymer matrix. The diameter of the glass fiber ranges between 3-20mm. glass is widely used as reinforcement due to the following reasons:
When new fibers of glass are drawn, they are coated with a size. This is a thin layer that protects the glass fiber from undesirable environmental conditions and other damages. Before composite Fabrication, the size is removed and is replaced with a coupling agent that promotes the bond between the polymer matrix and the fiber.
The glass fiber reinforced plastic composite has high strength, but they are not used to construct airplanes or bridges because of their low rigidity and stiffness.
Glass Fiber reinforced Plastics – GFRP holds many applications, some of them include:
In Carbon Fiber Reinforced Polymer CFRP composites, the carbon fibers provide stiffness and strength to the polymer composites, whereas the polymer matrix holds the fibers together to provide some toughness.
Advantages of using Carbon Fiber Reinforced Polymer Composites CFRP
Applications of Carbon Fiber Reinforced Polymer CFRP
The first organic fiber used as reinforcement in polymer composites was an aramid-fiber reinforced polymer. When compared to steel and glass fibers, aramid fibers have better mechanical properties and equal weight. This group of materials is known as the poly para phenylene terephthalamide.
Kevlar and Nomex are the most common aramid materials. Having high strength and moduli, these fibers are weak in compression. These fibers are susceptible to degradation by strong acid and bases and are stable at high temperatures (-200°C to 200°C).
Applications of Aramid fiber reinforced polymer composites – AFPC
Metal Matrix Composites
The matrix materials of M.M.C.’s are ductile metal.
The advantages of M.M.C.’s over P.M.C.’s include
Ceramics Matrix Composites C.M.C.’s, the fibers, whiskers, or particulates of the ceramic’s internal toughness are embedded together into the ceramic polymer matrix. This technique increases the toughness of the polymer composite. The Ceramics Matrix Composites C.M.C.’s are fabricated by liquid phase sintering, hot pressing, and hot isotactic techniques.
The interaction between the advanced cracks formed and the dispersed phase particles improves the fracture toughness properties.
Transformation toughening is a technique in which partially stabilized zirconia is dispersed into the matrix material to retain the metastable tetragonal phase at ambient conditions.
The stress causes the particles to transform the monoclinic phase.
If there is a slight increase in particle volume, producing compressive stresses near the tip’s surface. This stops the growth of the particle.
Reasons that cause is crack propagation n the ceramic whiskers:
Applications of Ceramics Matrix Composites C.M.C.’s
Dome of the applications of CMC’s include the following:
In the Carbon-Carbon Composites (C.C.C), the carbon fiber is reinforced into the carbon fiber matrix. These composites are highly resistant to thermal shocks and have high tensile strength and moduli. The major drawback is that they are susceptible to oxidation at higher temperatures.
The processing techniques of such composites are complex, and hence the techniques for production are expensive. This is because carbon fibers are impregnated into the
polymer resin, and then to give it the final shape, we allow the resin to cure.
Applications of Carbon-Carbon Composites:
These contain glass fibers and carbon fibers. These types of composites are good for sports and orthopaedic components.
Applications of hybrid composites
The sandwich panels consist of 2 sheets that are separated by less dense material. This has lower strength and stiffness. The core is foamed or made of honeycomb materials.
These composites are made of many laminae. The Lamina is thin, about 0.1mm to 1mm.
The composite material’s behavior is based on the individual elements’ combined behavior: the polymer matrix, the fiber/interface, and the reinforcing element. The interfacial adhesion must be strong so that the mechanical properties of the composite materials are strong. The matrix molecules determine the extent of interfacial adhesion.
Shape and Orientation of Dispersed Phase Inclusions
The particles are mainly used to improve the properties of the isotropic materials and have no preferred directions. The shapes of the reinforced particles can be cubic, regular or irregular, or spherical. The particulate reinforcements have directions that are almost equal in every direction.
Properties of the Matrix
The properties of the polymer will determine the application of the matrix.
The main added advantages include:
Thermoplastic polymers contain branched or linear molecules that have weak intermolecular and strong intramolecular bonds. The application of heat and pressure can reshape these polymers. These can either be semi-crystalline or amorphous in structure.
The plastic materials can be melted or softened by heating, and they get set again when cooled is called Thermoplastics.
Types of thermoplastics:
Thermoplastic Properties and applications
Properties of Thermoplastic polymers
Polyether ether ketone, Polysulfone, Nylons, Polyacetals, Polyamide-imides, Polycarbonate, Polyphenylene sulfide, Polyetherimide, Polyethylene, Polypropylene, Polystyrene.
A Thermosetting polymer is also known as a thermoset. It is a polymer that has heavily branched molecules that have a cross-linked structure.
The Thermosetting polymers are in their viscous state or soft solid state. These polymers undergo extensive cross-linking, which results in becoming insoluble products that are irreversibly hard.
One of the most important properties of thermosetting polymers or plastics is that they become hard in their molding process. After the polymers are solidified, they cannot become softened in any other circumstances.
The thermosetting polymers, after they are molded, acquire a three-dimensional shape and have a cross-linked structure. The covalent bonds that the structure produces acquire the polymer to retain its strength and structure even if it is very high. Thermoset resins are insoluble.
The processing of the Thermoset usually occurs in three stages.
Stage One- The first stage of the thermosetting process is known as the resole stage. In this stage, the resin is in an insoluble state and a fusible condition.
Stage Two- The thermoset resins in the second stage are partly soluble. In this stage, they tend to show similar characteristics to a thermoplastic where the changes are reversible.
The temporary state of a thermoset lasts for only a couple of minutes in its molten form. When the thermosets are in their molten state, they start forming cross-links as soon as there is more temperature increase.
Stage Three- this is when the cross-linking reaction occurs in the polymers. In this stage, the final structure of the thermoset polymers is created. This stage is similar to the molding stage, where the polymers are under controlled temperature and pressure.
The end product of the network structure consists of many cross-linked polymer chains. Once this polymer is formed, it cannot be thermally deformed under any circumstances.
The different kinds of thermosetting polymers
Uses: Thermosetting Polymers
Industrial equipment housings, coatings, tool housings, brackets, automotive body panels, and fender/wing walls.
Encapsulating for electrical components, laminates, coatings, casting compounds, and adhesives.
Knobs and electrical motor components, relays, laminates, adhesives, handles (pans and cooking pots), electrical switch housings.
Automotive body panels, foams, adhesives, and coatings, sealants.
Handles appliance components, adhesives, receptacles, closures, knobs, Electrical breakers, coatings, and laminates.
Electrical insulation, work surface laminates, and tableware.
Silicone, and polyimides, Polyesters, Phenolics, Ureas, Melamines, and Epoxies.
Polymers- Is a long or larger molecule consisting of a network or chain of repeating units. Polymers are formed by chemically bonding together many monomers that are identical or similar small molecules. A polymer is formed by the joining of many small monomer molecules by a process called polymerization.
Composites– Made up of multiple compounds, components, or complexes.
There are several polymers used in civil engineering infrastructure. such as-
Reinforced rubber products use the rubber matrix and combine another reinforcing material. This is done to achieve the desired flexibility and strength ratios.
The reinforcing material is usually a kind of fiber. This fiber is used to provide stiffness and strength. The rubber matrix has low stiffness and strength, and it is used to make the air-fluid tight and support its reinforcing materials to maintain the positions.
The positions are of great importance because they directly impact the mechanical properties of the composites.
Fiber reinforced components
These are fiber reinforced composite materials made of a polymer matrix reinforced with fibers.
The composer F.R.P. is used to strengthen the slabs, columns, and other beams. Even if the components’ structures are damaged due to the loading conditions, it is possible to increase their strengths.
The first human-made fiber-reinforced component was a raincoat. Charles Macintosh, a Scottish man, came up with this idea in the nineteenth century. He remembered that cotton is a form of a natural polymer called Cellulose.
This fiber that is embedded into the matrix is used to make the material stronger. The reason why fiber-reinforced composites are used is that their properties make them strong and lightweight. These composites are stronger than steel but weigh much lesser. This is why these composites are often used in automobiles as they make it fuel-efficient, and lesser pollution is emitted.
F.R.P. in Civil Infrastructure
F.R.P. is most popular in rehabilitation. This is the renewal of the construction of the buildings, pipelines, bridges, and other infrastructures.
The process of rehabilitation includes repairing damaged and deteriorated civil infrastructure.
Use of FRP in bridge rehabilitation
There are many parts of the bridge where FRP.’s are used:
Use of F.R.P. in bridge deck and stringer
The F.R.P.’s are used to increase the service life of the bridge decks. Because of their lightweight, this reduces the construction of the time of the bridge deck.
Use of FRP in the abutment panel
The FRP composite panels provide a strong, durable, and lightweight structure. This structure will not rust like steel, rot like Wood, or spall like concrete.
Due to the corrosion-resistant and fatigue properties, the abutment panels have a long service life and a reduced maintenance cost.
Use of F.R.P. in the retaining structure
The high-temperature resistance, lightweight insulation, high strength and corrosion-resistance properties of F.R.P.’s are used in the retaining wall structure.
Use of FRP in the Parapets
The Parapet is strengthened with the help of Fibre Reinforced Polymer (F.R.P.). The F.R.P. is a cost-effective alternative to strengthen the parapets.
Use of FRP in the Parapets
Carbon fiber reinforced polymers (CFRP) are used for the effective strengthening of the steel girder bridges. The C.R.P. improvises the live load carrying capacity of the steel bridges.
Practical Applications of F.R.P. Bridges
There are many countries adopting FRP for the construction of bridges and their rehabilitation processes. Some of them are given below:
The Joffer bridge in Canada
For the rehabilitation of the Joffer Bridge in Canada, different F.R.P.’s are used to strengthen the sidewalk, the concrete deck slab, and the traffic barrier.
Additionally, fiber petro strain sensors are installed in the steel girders and the F.R.P. grid. This helps develop an understanding of traffic loading and environmental conditions.
This Wickwire Run Bridge was in critical condition and had to be replaced. In July 1997, a new bridge was constructed using F.R.P. The composite deck modules 500 are supported by wide flange steel beams.
Advantages of using F.R.P. for civil infrastructure/construction applications
Greater initial expense
Many engineers and constructors are not familiar with F.R.P.
There is an increment of deflections due to the low modulus of elasticity,
The F.R.P.’s lack the required load-bearing capacity to handle the wall structures and the high-performance deck.
To build a bridge faster with low maintenance, one may use FRP’s.
FRP in the Automotive industry
31% of FRP is used in the automotive industry.
Other vehicles include Stout 46, Ford Thunderbird – 1954, Chevrolet Corvette fiberglass body – 1953.
Why use composite parts in the automotive industry?
The replaceable body parts in the vehicles
Fabrication methods used
Adaptations for the automotive processing
Natural Fiber Composites
The natural fibers are biodegradable, renewable, and non-abrasive. These possess a good calorific value, are inexpensive, and possess good mechanical properties.
The natural fibers are environmentally friendly, and that is why they are used extensively in the market.
Natural Composites exist in both plants and animals. A popular example is Wood. Made of cellulose fibers (polymer) and held together by a weaker substance named Lignin. These two substances form a strong bond. Cellulose is also found in cotton, but due to the absence of Lignin, it is much weaker.
The bones inside your body are also natural composites. It is made of a hard and brittle material named hydroxyapatite and flexible material called collagen. The collagen is found in other parts of your body too much as your fingernails and your hair. But without hydroxyapatite, they are not strong enough.
Composites have been a part of human life for over a thousand years. One such example of an early composite is mud bricks.
Early mankind have noticed that you can dry mud out easily, and one can give it shape to building material. It does not break if one tries to squash it ( because it has high compressive strength), but if one tries to bend it (due to its low tensile strength), it breaks easily. In contrast, straw can be stretched easily. Therefore by mixing both of these materials, early men made mud bricks resistant to squeezing and tearing.
Concrete is another example. Concrete is a mixture of sand, stone, and cement. This gives it good compressive strength. You can increase concrete’s tensile strength by adding wires or rods. The concrete that contains such materials is known as reinforced concrete.
Based on their origin, Natural composites are categorized into the following:
Plant fibers mainly consist of Cellulose. Examples- Flax, Sisal, Hemp, Ramie, Jute, Bamboo, Cotton, and Coir.
These cellulose fibers find many applications:
Animal and Mineral Fibers
Mineral Fibers are those fibers that are extracted from minerals. These are either naturally occurring fibers or changed fibers.
Animal fibers contain a large number of proteins. Such as mohair, downy, cases, silk, alpaca. The animal strands are the animal’s hair, such as horsehair, alpaca hair, Sheep’s downy, goat hair, and so on.
Banana plant is a large herb that has leaves and emerges from stems. The height of the banana plant varies between 10-50 feet. Each plant is surrounded by at least 8-12 large leaves. The fibers are the waste end product of banana cultivation. So, without any additional costs, these fibers are sent for industrial purposes.
Bananas produce textiles fibers. They grow easily in young shoots and are usually found in hot climatic regions.
All the banana plants have large fibers. This plant is a good source for the textile industry, especially in countries like Nepal and Japan
Properties of Banana Fiber
Required materials for preparation
The banana fiber is removed from the banana plant. The extracted fibers are dried out in the sun and then in the oven. This is used to remove the water content from the fiber. The fiber is mixed with the matrix mixture by simple stirring, and the mixture is poured slowly into molds of different sizes.
The releasing agent is used on the mold sheet and used to remove the composite from the mold easily. After pouring into the mold cavity, it is heated to 30 degrees. It is heated for 24 hours. A load is put on the mold constantly. After the curing is done, the specimen is taken out from the mold.
Composition of the materials in the banana composite: