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Introduction to Polymer composites
This document provides an introduction to polymer composites. It defines composites as materials made of two or more chemically and physically distinct phases separated by a distinct interface. Composites combine materials to achieve properties not attainable by the individual components alone. The matrix phase holds the dispersed reinforcing phase and shares the applied load. Polymer composites offer advantages like high strength and stiffness, as well as good impact and corrosion resistance. Properties depend on factors like interfacial adhesion between phases, shape and orientation of the dispersed phase, matrix properties, and size and concentration of the dispersed phase. Processing methods for polymer composites include hand lay-up, injection molding, and pultrusion. Dental composites contain resin
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Introduction to Polymer composites
- 1. Introduction to Polymer composites MohamedMahmoud Abdul-Monem
- 2. Introduction • Composites canbe defined as materials that consist of two or more chemically and physically different phases separated by a distinct interface. • The different systems are combined to achieve a system with more useful structural or functional properties non-attainable by any of the constituent alone. • The basic difference between blends and composites is that the two main constituents in the composites remain recognizable while these may not be recognizable in blends.
- 3. • Most primitiveman-made composite materials were straw and mud combined to form bricks form building construction
- 4.
- 5. • Composite materialis a material composed of two or more distinct phases (matrix phase and dispersed phase) and having bulk properties significantly different from those of any of the constituents. • Matrix phase is the primary phase having a continuous character. • Matrix is usually more ductile and less hard phase. • It holds the dispersed phase and shares a load with it. • Dispersed (reinforcing) phase is embedded in the matrix in a discontinuous form. • Dispersed phase is usually stronger than the matrix.
- 9. Advantages of polymercomposites a) High strength b) High stiffness c) High fracture resistance d) Good abrasion resistance e) Good impact resistance f) Good corrosion resistance g) Good fatigue h)Low cost
- 10. Disadvantages of polymercomposites a) low thermal resistance b) high coefficient of thermal expansion.
- 11. Factors affecting propertiesof polymer composites 1. Interfacial adhesion 2. Shape and Orientation of Dispersed Phase 3. Matrix properties 4. Concentration of dispersed phase 5. Size of dispersed phase
- 12. Factors affecting propertiesof polymer composites 1.Interfacial adhesion • To attain superior mechanical properties the interfacial adhesion should be strong. • Matrix molecules can be anchored to the fiber surface by chemical reaction or adsorption
- 13. Factors affecting propertiesof polymer composites 2.Shape and Orientation of Dispersed Phase The shape of the reinforcing particles can be: • Spherical, • Cubic, • Platelet, • Regular or irregular geometry.
- 14. Factors affecting propertiesof polymer composites • 3.Polymer matrix Varieties of polymers for composites are : • Thermoplastic polymers, • Thermosetting polymers, • Elastomers, • Blends.
- 15. Thermoplastic polymers • Thermoplasticsconsists of linear or branched chain molecules having strong intramolecular bonds but weak intermolecular bonds. • They can be reshaped by application of heat and pressure and are either semicrystalline or amorphous in structure. • E.g. polyethylene, polypropylene, polystyrene
- 16. Thermoset polymers • Thermosetshave cross-linked or network structures with covalent bonds with all molecules. • They do not soften but decompose on heating. • Once solidified by cross-linking process they cannot be reshaped. • E.g. epoxies, polyesters, phenolics, ureas.
- 17. Elastomers • An elastomeris a polymer with the property of viscoelasticity, generally having notably low Young’s modulus and high yield strain compared with other materials. • Elastomers are amorphous polymers existing above their glass transition temperature, so that considerable segmental motion is possible. • E.g Natural rubber, synthetic polyisoprene, polybutadiene,
- 20. Polymer composites interfacecharacterization • The characterization of interface gives relevant information on interactions between fiber and matrix. • The mechanical properties of fiber-reinforced composites are dependent upon the stability of interfacial region. 1. Micromechnical : fiber-pullout & micro-debond test 2. Spectroscopic : XRD & EDX 3. Microscopic: Opitcal microscope,SEM,TEM & AFM 4. Thermodynamics: wettability & contact angle.
- 21. Fiber pullout testContact angle
- 22. Processing of Polymercomposites 1. Hand lay-up 2. Bag molding 3. Pultrusion 4. Filament winding 5. Preformed molding 6. Injection molding 7. Spray up
- 23.
- 24. Dental composites Dental composite Resin matrixFillers Silane coupling agent
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