4- General Intro to Polymers

Question 1

what is polymer (break down of word)

Answer 1

many repeat unit

Question 2

saturated hydrocarbons

Answer 2

each carbon is fufilled with as many hydrogens

Question 3

double bond

Answer 3

ethylene or ethane

Question 4

tripe bond

Answer 4

acetylene or ethyne

Question 5

most polymers are defined by

Answer 5

chemical composition
molecular wieght
molecular structure

Question 6

degree of polymerization (DP)

Answer 6

how many monomers are in a chain

Question 7

chain length (l)

Answer 7

end to end distance of a stretched out molecule

Question 8

molecular weight (mw)

Answer 8

weight of chain

Question 9

end-to-end distance (r)

Answer 9

distance between ends of randomly coiled chain

Question 10

what are methods of molecular weight determination?

Answer 10

number average molecular weight

weight average molecular weight

viscosity average molecular weight

molecular weight distribution

Question 11

molecular weight

Answer 11

mass of a mole of chains

Question 12

define polydisperisty index (PDI)

Answer 12

Ratio of Mw to Mn

Question 13

degree of polymerization

Answer 13

n= number of repeat units per chain

Question 14

define conformation

Answer 14

molecular orientation that can be changed by rotation around bonds

Question 15

define tacticity

Answer 15

stereoregularity of chain

isotactic
syndiotactic
atactic

Question 16

define isotactic

Answer 16

all R groups on same side of chain

Question 17

syndiotactic

Answer 17

R groups alternate sides

Question 18

atactic

Answer 18

R groups random

Question 19

Cis/trans isomerism

Answer 19

cis- bulky groups on same side of chain

trans- bulky groups on opposite sides of chain

Question 20

copolymers

Answer 20

two or more monomers polymerized togeher

random
alernating
block
graft

Question 21

random (copolymer)

Answer 21

A and B randomly vary in chain

Question 22

alternating (copolymers)

Answer 22

A and B alternate in polymer chain

Question 23

block (copolymers)

Answer 23

large blocks of A alternate with large blocks of B

Question 24

graft (copolymers)

Answer 24

chains of B grafted on to A backbone

Question 25

spherulites

Answer 25

fast growth-forms lamellar (layered structures)

Question 26

what four fall under the classification of polymers?

Answer 26

thermoplastics, thermosets, elastomers or rubbers, composites

Question 27

thermoplastic polymers

Answer 27

long chains with limited or no cross-linking
behave like plastic, ductile manner
melt when heated and thus are easily remolded and recycled

Question 28

thermoset polymers

Answer 28

highly cross linked, 3d network structures
generally brittle
decompose when heated and cant easily be reshaped or recycled

Question 29

elastomers and rubbers

Answer 29

large amounts of elastic deformation
some cross linking
crosslinks allow material to return to original shape without plastic deformation

Question 30

name some polymer additives

Answer 30

fillers- added to improve tensile strength and abrasion resistance

stabilizers-antioxidants, uv protectants

lubricants- added to allow easier processing, slides throug hdies easier

colorants

flame retardants

Question 31

thermoplastic

Answer 31

can be reversibly cooled reheated, recycled

heat till soft, shape as desired, then cool

polyethlylene, polyproplene,polystyrene