Polymers Flashcards
Define a Polymer
Polymers are long chain giant organic molecules which are assembled from many smaller molecules called monomers
What is the c-c bond angle
Carbon to carbon bonds lie at 109 Degrees
name characteristics of polymers
Low Density, Low melting point, High elongation, Low thermal conductivity, Resistive, Transparent, Easily Coloured, Solvent Sensitivity, Flammable
What is Polymerisation
Process of sticking polymers together - with an initiator or catalyst
What is a copolymer
Polymer made up from two different monomers e.g. Nylon
Describe the structure of a polymer crystal
Chain folded structure for plate shaped polymer crystallite, all molecule chains follow the long order arrangement
Describe the mechanical behaviour of polymers
Visco-elasticity. It exhibits both viscous and elastic properties when undergoing deformation.
Describe vulcanisation and how it effects mechanical properties
The adding of cross links to polymer chains in rubber. done through the addition of sulphur. Increases the amount of stress rubber can withstand
What is a thermoplastic
No cross links between chains, weak forces of attraction (can be broken by warming). Plastically deforms under stress
what is a thermoset
Extensive cross linking formed by covalent bonds, bonds prevent the chains moving relative to each other. Elastic, when deformed it returns to original shape
How do polymers react to cold drawing
Cold drawing creates necking where the polymer chains become aligned which increases the polymer strength
