Question

Car tires are basically polymer. What makes car tires resistant to wear? Explain how?                                                                                                                                                                                                                                                                                                                                                                                                                  What would you suggest for face hardening of the following materials: An excavator teeth made of 1040Q:                                                                                 Internal gears of a Swiss watch:                                                                                   What would you suggest for face hardening of the following materials: A gear made of AISI 1080 carbon steel                                                                            : a nail made of AISI 1020 carbon steel______________________________________

4. Elastomers have an exceptionally large amount of elastic deformation due to:

1. the high modulus of elasticity
2. the HCP structure
3. significant amounts of cross linking
4. the high sulphur content
5. the coil shaped polymer chains
6. all of the above

                                                                                                                                   

5. Explain why pulling a plastic shopping bag makes it stronger. Describe the mechanism.

    

                                                                                                                                   

                                                                                                                                   

                                                                                                                                   

  

                                                                                                                                   

                                                                                                                                   

Answer 1

Natural and synthetic rubber are the main components of a car tyre. Fillers are added to rubber and that makes resistant to wear.Some of the fillers are silica, carbon black or chalk.They bind the rubber and make it more resistant to wear.

Face hardening should be done for internal gears of a Swiss watch because it is the process of hardening the surface of steel with low carbon content which allows the metal deeper underneath to remain soft, thus forming a thin layer of harder metal at the surface.

Face hardening should be done for a nail made of AISI 1020 carbon steel because it is the process of hardening the surface of steel with low carbon content which allows the metal deeper underneath to remain soft, thus forming a thin layer of harder metal at the surface.

Elastomers have large amount of elastic deformation due to the coil shaped polymer chains. A large number of cross-links would make the material rigid, hard, and closer in properties to a thermoset