2339 Week 3 Asyn_Generic polymer nomenclature and properties

Question 1

Properties of materials/ Polymers

Answer 1

Question 2

What are thermoplastics

Answer 2

• 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)

Question 3

How does the monomer influence the properties of the polymer

Answer 3

• 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.

Question 4

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

Answer 4

• 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

Question 5

How chain length of polymers effects melting/ boiling point

Answer 5

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

Question 6

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

Answer 6

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

Question 7

Diagram of crystallinity in polymers

Answer 7

Question 8

How crystallinity effects properties of a polymer

Answer 8

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

Question 9

Describe what tacticity is, there are three groups

Answer 9

Question 10

How side branching effects polymer density, and polymer properties

Answer 10

• 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

Question 11

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

Answer 11

• 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

Question 12

How crosslinks are formed, V______, or F_____ R______ P________

Answer 12

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

Question 13

Describe the structure and properties of elastomers

Answer 13