intro to polymers e lec

Question 1

what is alginate

Answer 1

a hydrocolloid

Question 2

give an example of a natural polymer

Answer 2

collagen

Question 3

what is a denture material made out of

Answer 3

the vulcanisation of rubber

Question 4

when did we see alginate impressions

Answer 4

since the second world war

Question 5

what did we see since the second world war

Answer 5

the poly methylmethacrylate and alginate impressions and acrylic base denture resin

Question 6

what language does the world polymer come from

Answer 6

greek

Question 7

what does polymer mean in greek

Answer 7

many parts

Question 8

how many carbons does ethene have

Answer 8

it has 2 carbons

Question 9

how many hydrogens does ethene have

Answer 9

it has 4 Hs

Question 10

what is in the ethene molecule which makes it special

Answer 10

a double bond which is relatively easy to break

Question 11

how can we write a repeated unit of a mer

Answer 11

by adding a bracket and a n outside the bracket

Question 12

the n is called the

Answer 12

degree of polymerisation

Question 13

how can we calculate the molecular mass of the polymer

Answer 13

by the degree of polymerisation and the product of the molecular mass

Question 14

what are the three types of co polymer

Answer 14

block
graft
random co polymer

Question 15

what can co polymers do

Answer 15

tailor the properties of the final material

Question 16

what is a straight polymer called

Answer 16

a linear polymer- a simple polymer

Question 17

if the chain is branched off the main backbone it can resemble a

Answer 17

graft co polymer

Question 18

if the branched polymer attaches to another it can form

Answer 18

a 3D structure which is said to be cross linked

Question 19

what is an example of cross linking in dentistry

Answer 19

a alginate impression material

Question 20

which type of polymer can be melted and remodelled

Answer 20

linear or branched- and they are called thermoplastic

Question 21

what type of waxes do we use in dentistry

Answer 21

thermoplastic

Question 22

which type of polymer does not melt and rest

Answer 22

cross linked

Question 23

in dentistry which example do we have of a thermoset polymer

Answer 23

poly methylmetacrylate(PMAA)/acrylic

Question 24

what is polymerisation

Answer 24

the act of reacting the monomers or comonomers into a polymer

Question 25

what are the two main branches of polymerisation

Answer 25

condensation polymer | addition polymer

Question 26

what is condensation polymerisation

Answer 26

it is where the monomer reacts to form a polymer and a small by product is produced

Question 27

what is addition polymerisation

Answer 27

it is when monomers great together but no by product is produced

Question 28

condensation polymers grow by

Answer 28

step growth

Question 29

what is the most common by product

Answer 29

water

Question 30

what can also be a by product

Answer 30

low molecular weight alcohols

Question 31

how does addition polymerisation occur

Answer 31

by a chain reaction

Question 32

name the four steps of the chain reaction

Answer 32

activation initiation propagation termination

Question 33

what chemical is added to the monomer

Answer 33

the initiator

Question 34

what is the initiator sensitive to

Answer 34

heat light additional chemicals

Question 35

what does activation do

Answer 35

split the initiator molecule so that there are very reactive free radicals

Question 36

what does the initiation stage have

Answer 36

the very reactive free radicals which hone into the weaker points in the monomer

Question 37

what happens in the propagation step

Answer 37

the free radical binds and then gets passed on to the other monomer

Question 38

during termination

Answer 38

the free radical must either meet another free radical or join to a hydrogen

Question 39

what is it called when two free radicals join in the termination step

Answer 39

combination

Question 40

what is it called when the free radical binds to a hydrogen in the termination step

Answer 40

disproportionation

Question 41

what happens when a double bond is broken

Answer 41

heat is given out exothermic

Question 42

what are the clinical considerations for breaking a double bond

Answer 42

it can become uncomfortable for the patient

Question 43

the conversation from methyl methacrylate to polymathy methacrylate

Answer 43

can reduce in volume by 30%

Question 44

how do we reduce the volume lost

Answer 44

by using filler particles of a material that doesn't change volume

Question 45

which particle is used in PMAA

Answer 45

particles that have been previously polymerised polymer

Question 46

what does Mm stand for

Answer 46

mean molecular mass

Question 47

what is different amount the graph

Answer 47

the graph is skewed so the mean lies funny

Question 48

how can this be fixed that the graph is skewed

Answer 48

this can be rectified by taking the “number average molecular mass” this calculates what length chain the average (mean) monomer resides in.

Question 49

what structures can polymers form

Answer 49

crystalline or amorphous

Question 50

what structure is crystalline

Answer 50

a highly ordered structure

Question 51

what structure is amorphous

Answer 51

random loose net work which is toucher

Question 52

what structure are most polymers

Answer 52

a mixture of the two structures

Question 53

this can depend on

Answer 53

chemistry and processing

Question 54

what does Tg mean

Answer 54

gasses transition temperature

Question 55

what is the temp of tg

Answer 55

lower than the melting point

Question 56

polymers below Tg are said to be

Answer 56

glassy

Question 57

polymers above Tg are said to be

Answer 57

rubbery

Question 58

the longer the chain group the

Answer 58

lower the Tg

Question 59

why does the tg become lower in the longer chain group

Answer 59

as they push the pendants far apart