Polymers Flashcards
(12 cards)
What is a polymer?
A large molecule made up of many monomers
What is a monomer?
A single unit within a polymer
What are the two polymerisation reactions?
Addition - forms polymers from ethene monomers
Condensation - forms polymers from monomers
What are the two types of synthetic polymers, and what are their properties?
Thermoplastic - softens under heat, easily recyclable
Thermosetting - do not change shape under heat, not easily recyclable, stronger than thermoplastic
Are polymers usually soluble or insoluble?
Insoluble
How does biodegradability differ depending on the type of reaction that forms a polymer?
Condensation - polymers produced by condensation are easily reversible, and therefore more biodegradable
Addition - more difficult to reverse, not biodegradable and harmful to the environment
Describe tensile strength and cross linking
Tensile strength - the resistance of a substance to be pulled or stretched
Cross linking - joins linear polymer chains through ionic or covalent bonds between chains. Increases tensile strength.
What are three factors that affect density?
Branching, side groups, and chain length
How does branching affect density?
Branching decreases density because branched chains cannot pack as closely
How do side groups affect the properties of polymers?
Larger side groups decrease flexibility. Replacing atoms stiffens the polymer
How does chain length affect the properties of polymers?
Longer chains have higher melting points due to intermolecular forces. They are also harder substances
Describe some properties of crystalline polymers
- Higher density due to closer packing
- Higher melting points due to stronger intermolecular forces
- Opaque
- Resistant to chemicals due to close packing
