2339 Week 3 Asyn_Generic polymer nomenclature and properties Flashcards

1
Q

Properties of materials/ Polymers

A
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2
Q

What are thermoplastics

A
  • large group of polymers, properties all defined by secondary forces
  • no chemical forces between chains, allowing flow
  • Despite all being thermoplastics, they all have very different properties (brittleness, strength)
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3
Q

How does the monomer influence the properties of the polymer

A
  • the nature of the monomer and the functional group within it, can influence overall properties, type of bond within the polymer and between polymer chains (ie polar, hydrogen)
  • affecting strength between chains
  • size of monomer, how many sites of secondary forces influences bond strength between chains
  • Sum of all bonds= close packing when bonds are strong, impacting strength. Loose polymer will be more flexible.
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4
Q

Monomer effect (how ring structures can impact stiffness and Tg)

A
  • bulks up, decreases chain movement
  • eg PET vs Polycarbonate has two rings, and higher Tg
    -copolymerisation combines properties of different monomers eg. spandex
    is both elastic and strong
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5
Q

How chain length of polymers effects melting/ boiling point

A
  • increase in molecular weight increases tensile strength
  • longer chains tangle together and restrict ability to flow
  • ## ability of chains to tangle (entropy)
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6
Q

Diagrams showing increase in Tg and entanglement (entropy) in Alkanes

A
  • PEG, the number refers to the average molecular weight, from a liquid, to sticky waxy polymer, to a solid
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7
Q

Diagram of crystallinity in polymers

A
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8
Q

How crystallinity effects properties of a polymer

A
  • crystalline has good heat and chemical resistance, harder to separate
  • amorphous less dense and more flexible
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9
Q

Describe what tacticity is, there are three groups

A
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10
Q

How side branching effects polymer density, and polymer properties

A
  • reduces sites for secondary bonding, as reduces packing and lowers density, this lowers strength and melting point
  • very long side branches, can be tougher due to entanglement
  • bulky ring structures can make it stiffer
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11
Q

Network Polymers, or T______ Polymers, describe structure and bonding, and how this effects properties

A
  • covalent bonds between polymer chains, once formed, cannot be reformed or shaped
  • thermosetting
  • polymer with lots of crosslinks is rigid, chemically brittle and low impact strength
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12
Q

How crosslinks are formed, V______, or F_____ R______ P________

A
  • through introducing a cross linking agent, eg hardener in epoxy resin
  • heat or high energy irridation
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13
Q

Describe the structure and properties of elastomers

A
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