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 Introduction  Basic Topics: o Structure of polymers o Mechanical Properties of Polymers  Applications of Polymers

 Polymers are long chain giant organic molecules are assembled from many smaller molecules called monomers. Polymers consist of many repeating monomer units in long chains. A polymer is analogous to a necklace made from many small beads (monomers).  Another common name for many synthetic polymers is plastic which comes from the Greek word "plastikos", suitable for molding or shaping. Many objects in daily use from packing, wrapping, and building materials include half of all polymers synthesized.

1)Configuration  The two types of polymer configurations are cis and trans. These structures can not be changed by physical means (e.g. rotation).  Three distinct structures can be obtained :  Isotactic is an arrangement where all substituents are on the same side of the polymer chain.  syndiotactic polymer chain is composed of alternating groups  atactic is a random combination of the groups.

2)Conformation  The two atoms have other atoms or groups attached to the two atoms that are joined by a single bond then configurations which vary in torsional angle. 3)Other Chain Structures  A branched polymer is formed when there are "side chains" attached to a main chain.  Star branching-when a polymerization starts with a single monomer and has branches radially outward from this point.  Dendrimers-Polymers with a high degree of branching.

 Copolymers-polymers that incorporate more than one kind of monomer into their chain.  A random copolymer contains a random arrangement of the multiple monomers.  A block copolymer contains blocks of monomers of the same type.  A graft copolymer contains a main chain polymer consisting of one type of monomer with branches made up of other monomers. Block Copolymer Graft Copolymer Random Copolymer

4)Cross-Linking  When the polymer is stretched, the cross-links prevent the individual chains from sliding past each other. The chains may straighten out, but once the stress is removed they return to their original position and the object returns to its original shape.  vulcanization-a series of cross-links are introduced into an elastomer to give it strength. This technique is commonly used to strengthen rubber.

 Tensile strength  a material quantifies how much stress the material will endure before suffering permanent deformation. This is very important in applications that rely upon a polymer's physical strength or durability.  Young's modulus of elasticity  quantifies the elasticity of the polymer. It is defined, for small strains, as the ratio of rate of change of stress to strain.  The modulus is strongly dependent on temperature.  Viscoelasticity describes a complex time-dependent elastic response, which will exhibit hysteresis in the stress-strain curve when the load is removed.

Polymeric materials are used in and on soil to improve aeration, provide mulch, and promote plant growth and health. Medicine Many biomaterials, especially heart valve replacements and blood vessels, are made of polymers like Dacron, Teflon and polyurethane. Consumer Science Plastic containers of all shapes and sizes are light weight and economically less expensive than the more traditional containers. Clothing, floor coverings, garbage disposal bags, and packaging are other polymer applications.

Industry Automobile parts, windshields for fighter planes, pipes, tanks, packing materials, insulation, wood substitutes, adhesives, matrix for composites, and elastomers are all polymer applications used in the industrial market. Sports Playground equipment, various balls, golf clubs, swimming pools, and protective helmets are often produced from polymers.