Polymers 2

Question 1

Molecular Weight (MW)

Answer 1

Sum of elemental masses

Question 2

Degree of polymerization

Answer 2

DP=MW poly/MW mono

Question 3

Average degree of polymerization

Answer 3

avg. num of structural units

Question 4

Average molecular weight

Answer 4

avg. DP time MW (mer)

Question 5

Number average MW

Answer 5

M_n = sum(M_i*M_i) / sum(N_i)

sum(chain weight*# chains) / sum (# chains)

Question 6

Weigh average MW

Answer 6

M_w = sum([M_i]^2N_i)/(M_iN_i)

sum(chain W^2#) / sum(chain W#)

Question 7

Polydispersity Index

PDI

Answer 7

M_w / M_n

>1

Question 8

MW effect on matter state

Answer 8

Low = Gas
Med = Liquid
High = Solid

Question 9

Polymerization synthesis

Answer 9

Addition

Condensation

Question 10

Addition Polymerization

Chain

Answer 10

Placing additional monomers to the end of a chain
MW increases quickly, but monomer consumption slowly
Broad MW distribution

Question 11

Condensation Polymerization

Step

Answer 11

Eliminates some atoms during reaction
Reaction takes place at multiple sites
MW increases slowly, but monomer consumption quickly
Narrow range of MW

Question 12

Free Radical

Answer 12

Active site during chain Polymerization

Question 13

Polymer phases

Answer 13

Amorphous
Crystalline
Semi-crystalline

Question 14

Crystallization

Answer 14

water to ice

Melting temp T_m

Question 15

Amorphous

Answer 15

window glass can flow

glass-rubber transition temp T_g

Question 16

Melting

Answer 16

When polymer chains lose their ordered or crystalline structures becoming disordered

Question 17

Glass Transition

Answer 17

Structure remains, but becomes soft and flexible

Question 18

Amorphous charc.

Answer 18

Spaghetti like
Glassy - random coils frozen
Rubbery - Coils can slide

Question 19

T_g factors

Answer 19

Chemical structure - double bonds, bulky pendant groups (?), branching increase by restricting rotation
MW - longer chains increase
Plasticizers

Question 20

Plasticizer

Answer 20

Small molecule used to reduce T_g

Caused by spacing chains and slide-ability

Question 21

Backbone flexibility

Answer 21

It increases then Tg goes down

Question 22

Bulky pendant groups

Answer 22

can either restrict motion (Tg up) or space chains (Tg down)

Question 23

Crystalline charc.

Answer 23

Closely packed linear patterns.

Flexible backbones and strong polarity increase