POLYMERS AND COMPOSITES (MATERIAL SCIENCE)

A PPT DESCRIBING ABOUT POLYMERS AND COMPOSITES FROM BASIC TO ADVANCE LEVEL. (A BRIEF INTRODUCTION).

1. POLYMERS AND COMPOSITES MATERIAL SCIENCE

2. CONTENTS ROADMAP POLYMERS TYPES OF POLYMERS BASED ON ORIGIN BASED ON PROPERTIES COMPOSITES PROPERTIES OF COMPOSITES COMPOSITES: A MIXTURE MATRIX REINFORCEMENT INTERACTION OF MATRIX AND REINFORCEMENT APPLICATIONS OF COMPOSITES REFERENCES 2

3. Ceramics Metals Polymers Composites 3

4. POLYMERS P olymer , any of a class of natural or  synthetic  substances composed of very large molecules, called macromolecules, that are multiples of simpler chemical units called  monomers .[1] The word ‘polymer’ is coined from two Greek words: poly means many and mer means unit or part. The term polymer is defined as very large molecules having high molecular mass (103-107u). [ 2] Polymers, also known as macromolecules , are formed by the joining of repeating structural units called monomers , which are reactive molecules. These monomers are linked by covalent bonds through a process known as polymerization . 4

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6. Types of Polymer (based on their properties) THERMOSETTING Thermosetting polymers are a type of polymer that irreversibly harden when exposed to heat or chemical curing processes. Unlike thermoplastics, which can be reheated and reshaped, thermosetting polymers form a rigid, cross-linked structure after curing, making them resistant to heat, chemicals, and deformation. They offer High strength and rigidity, Heat resistance, Chemical resistance however they cannot be recycled. Some examples are: epoxy resins, phenolic resins (Bakelite), and polyurethane. 6

7. THERMOPLAST Thermoplastics are a class of polymers that soften and become mouldable when heated and harden upon cooling. This process can be repeated multiple times without significantly altering the chemical properties of the material, allowing thermoplastics to be reshaped, remoulded, and recycled. When thermoplastics are heated, the weak intermolecular forces between polymer chains allow the chains to slide past one another, making the material flexible and soft. Upon cooling, these forces regain strength, solidifying the material. They offer Recyclability, Flexibility, Heat-sensitivity, Less rigidity. Some examples are Polyethylene (PE), Polyvinyl Chloride (PVC), Polypropylene (PP), Polystyrene (PS) 7

8. ELASTOMERS Elastomers are a type of polymer that exhibit exceptional elasticity, meaning they can stretch significantly and return to their original shape when the force is removed. This property comes from their molecular structure, which consists of long, flexible polymer chains that are lightly cross-linked, allowing them to move and stretch under stress but return to their initial arrangement once the stress is released. They offer Elasticity , Soft and flexible , Resilience , Thermosensitivity Examples: Natural Rubber, Silicone, Neoprene, Polyurethane 8

9. COMPOSITES Two inherently different materials that when combined together produce a material with properties that exceed the constituent materials. A Composite material is a material system composed of two or more macro constituents that differ in shape and chemical composition and which are insoluble in each other. A materials system composed of two or more physically distinct phases whose combination produces aggregate properties that are different from those of its constituents FIG. 1 carbon fiber ( fiber reinforced composite) 9

10. PROPERTIES OF COMPOSITES Composites can be very strong and stiff , yet very light in weight , so ratios of strength‐to‐weight and stiffness‐to‐strength to stiffness to weight are several times greater than steel or aluminium. Fatigue (it is the progressive and localized structural damage that occurs when a material is subjected to cyclic loading) properties are generally better than for common engineering metals. Toughness is often greater too. Composites can be designed that do not corrode (to destroy a metal or alloy gradually, especially by oxidation or chemical action) like steel. Possible to achieve combinations of properties not attainable with metals, ceramics, or polymers alone. 10

11. COMPOSITE: A MIXTURE In composite materials, matrix and reinforcement are two key components that work together to enhance the material's properties. The matrix is the continuous phase in a composite material, responsible for holding the reinforcement in place and distributing the loads or forces applied to the material. It acts as a binder, enveloping and protecting the reinforcement, and transferring the external stress to it. Key Roles of the Matrix: Binding : Keeps the reinforcement materials in place. Load transfer : Transfers stress to the reinforcement, which bears most of the load. Protection : Shields the reinforcement from environmental damage, such as moisture, corrosion, and UV rays. Shape : Gives the composite its shape and surface finish. Types of Matrix Materials: Polymers : Used in polymer matrix composites (PMCs) like fiberglass and carbon fiber -reinforced plastics. Metals : Used in metal matrix composites (MMCs), such as aluminium reinforced with ceramic fibers . Ceramics : Used in ceramic matrix composites (CMCs), offering high-temperature resistance and mechanical strength. MATRIX 11

12. Reinforcement is the dispersed phase in the composite material, which provides strength, stiffness, and other mechanical properties. It usually takes the form of fibers , particles, or flakes that are embedded within the matrix. The reinforcement material is typically much stronger and stiffer than the matrix, and its primary role is to improve the mechanical properties of the composite. Key Roles of Reinforcement: Strength enhancement : Provides mechanical strength and stiffness. Load bearing : Carries most of the load applied to the composite. Toughness : Improves resistance to fracture, impact, and fatigue. Types of Reinforcement Materials: Fibers : Most common form, includes carbon fibers , glass fibers (fiberglass), and Kevlar. Particles : Metal, ceramic, or polymer particles used in materials like concrete or metal composites. Whiskers and nanotubes : Microscopic reinforcements that improve strength at a nano or micro-scale. REINFORCEMENT The matrix provides ductility, shape, and protection, while the reinforcement offers mechanical strength and rigidity. The effectiveness of the composite depends on the proper bonding between the matrix and the reinforcement. The reinforcement usually carries the bulk of the load, and the matrix ensures the load is effectively distributed to the reinforcement and maintains structural integrity. Interaction Between Matrix and Reinforcement: 12

13. APPLICATIONS 1. Aerospace and Aviation Aircraft components : Fuselages, wings, tail sections, and interior parts are often made from carbon fiber -reinforced composites due to their high strength-to-weight ratio. Spacecraft : Lightweight, durable composites are used in satellites, space shuttles, and rockets for their ability to withstand extreme temperatures and conditions in space. 2. Automotive Industry Body panels and frames : Carbon fiber and fiberglass composites are used in performance vehicles for reducing weight, which improves fuel efficiency and speed. Electric vehicles : Lightweight composite materials help increase the range of electric vehicles by reducing their overall weight. Interior components : Composites are used in dashboards, door panels, and seats due to their durability and aesthetic flexibility. 3. Construction Bridges and buildings : Fiber-reinforced polymers (FRP) are used for reinforcing concrete, providing improved strength, durability, and resistance to corrosion in harsh environments. Roofing and cladding : Composites provide weather resistance and insulation in building exteriors. Structural reinforcement : Composites are used to strengthen aging structures, such as bridges and buildings, by wrapping them with FRP sheets or plates. 13

14. APPLICATIONS 4. Marine Industry Boats and yachts : Fiberglass-reinforced plastics are commonly used in hulls, decks, and masts due to their lightweight, corrosion resistance, and durability in water environments. Offshore structures : Oil platforms and underwater pipes use composites for their resistance to saltwater corrosion and high strength. 7. Wind Energy Wind turbine blades : Composites, particularly fiberglass and carbon fiber , are used to make long, lightweight, and strong blades for wind turbines, maximizing energy efficiency and lifespan. 8. Electrical and Electronics Circuit boards : Composite materials are used in printed circuit boards (PCBs) due to their electrical insulating properties and heat resistance. Enclosures and housings : Electronic devices use composites for cases and enclosures that are lightweight, durable, and resistant to corrosion and wear. 14

15. REFERNCES Britannica, The Editors of Encyclopaedia. "polymer". Encyclopaedia Britannica, 16 Sep. 2024, https://www.britannica.com/science/polymer. Accessed 26 September 2024 . NCERT textbook on Chemistry II ,class XI W. D. Callister, Fundamentals of Materials Science and Engineering, Wiley (2007) 15

16. Thank You 16