ch 8- polymers Flashcards
1
Q
addition polymerisation
A
chemical reaction between monomers resulting in the formation of a polymer
2
Q
alkene
A
hydrocarbon with at least one double carbon to carbon bond
3
Q
alkyne
A
hydrocarbon with at least one triple carbon to carbon bond
4
Q
condensation polymerisation
A
chemical reaction between monomers resulting in the formation of a polymer and water
5
Q
cross link
A
covalent bond between polymer chains
6
Q
thermosetting-cross linked polymers
A
polymer with covalent bonds/cross links that degrade or char when heated
7
Q
elastomers
A
polymer that forms occasional cross links and is elastic
8
Q
functional group
A
specific groups of atoms within a compound that affect the properties of the compound
9
Q
high density polyethene HDPE
A
tightly packed polymers produced at lower pressures
10
Q
linear- thermoplastic polymers
A
polymer with no cross links that can be remoulded when haeted
11
Q
low density polyethene LDPE
A
branched polymer produced at high pressures
12
Q
monomers
A
molecules that can react with other molecules to form larger molecules
13
Q
plastic
A
molecule produced synthetically from monomers bonded together
14
Q
polymer
A
molecule produced naturally or synthetically from monomers bonded together
15
Q
general formula for addition polymerisation
A
[C=C + C=C]n
->
-[-C-C-C-C-]-n
16
Q
general formula for condensation polymerisaiton
A
let R= any group where a carbon or hydrogen is attached to the rest
R-A-H + R-B-OH
->
R-A-B-R + H2O
17
Q
how does addition polymerisation work
A
the C to C double or triple bond is broken, allowing carbon atoms to form bonds with adjascent monomers
18
Q
how does condensation polymerisation work
A
two functional groupds react to form a bond between monomers- forming a polymer and water
19
Q
general formula for the formation of polyesters
A
(n+1) R(OH)2 + n R’(COOH)2 → HO[ROOCR’COO]nROH + 2n H2O
20
Q
polymer properties
A
light and strong
durable
highly versatile and modifiable
flammable
chemically resistant- particularly against acids
effective thermal and electrical insulators
21
Q
polar vs non polar polymers
A
non polar monomer are only held together by dispersion forces but when a polymer
22
Q
non polar polymer- tetrafluoroethene
A
polytetrafluroethene has strong dispersion forces between chains and other substances making it non stick
23
Q
polar polymer- polyacrylonitrile
A
make materials like carbon fibre which is found in tennis raquets and fishing rods.
the carbon nitrogen bond in acrylonitrile- the monomer, creates permanent dipole-dipole interaction between chains, giving them a high tensile strength and stiffness
24
Q
what determines the properties of a polymer
A
the monomer itself
the size and branching - the greater the chain length, the stronger the inermolecular forces due to greater surface material ( the strong intermolecular forces make the material tough)
polarity- physical properties of polymers as it creates certain attractions
25
how is low density polyethene produced
when polymerisation occurs at high temperatures and high pressures, polymers are unable to form linear chains
LDPE has many branches that extend from the parent chain
26
how do the branches prevent LDPE from becoming dense
the branches prevent them from packing close together, leading to weakened dispersion forces
27
LDPE properties
* Lower density (relative to DPE)
* Relatively soft
* Lower melting point (105115 C) (relative to DPE)
* Good chemical resistance
* generally opaque
28
how is high density polyethene produced
HDPE is produced under lower temperature and pressure conditions
little brancing and the polymer chains can pack together tightlyp
29
HDPE properties
higher density (relative to LDPE)
* hard
* higher melting point (120180 C) (relative to LDPE)
* Weatherproof and cold-resistant
* Good chemical resistance
* Allows light to pass through
* Insulator of electricity
30
polypropene- type of polymerisation
addition
31
polypropene- properties and applications
durable and cheap making it good for artificial turf and rope
32
polyvinylidene chloride- type of polymerisation
addition
33
polyvinylidene chloride- properties and applications
sticks to itself, making it good for food wrap
34
polyamide/nylon- type of polymerisation
condensation
35
polystyrene- type of polymerisation
addition
36
polystyrene- properties and applications
can be solid or foamed and can be used in cups, insulation foam or bean bags filling
37
linear polymers properties
when heated, they soften enabling them to be reshaped or remoulded
commonly sold as pellets that are heated then moulded to make a variety of plastics
intramolecular bonds of linear polymers are much stronger than the intermolecular forces holding the chains together
sufficient exposure to heat, individual chains become mobile and the plastic can be reshaped
38
how does the presence of cross links impact a molecule
it greatly restricts the movement of a molecule, making it more rigid and heat resistant
39
do thermoplastics have cross links
no
40
forces between chains in thermoplastics
weak intermolecular
41
thermoplastics- response to heat
softens/melts
42
thermoplastics- hardness
varies
43
elastomers- cross links
a few giving them elasticity
44
elastomers- forces between chains
weak intermolecular forces and occasional strong covalent bonds
45
elastomers- response to heat
varies- stretch and return to original shape
46
elastomers- hardness
varies
47
thermosets- cross links
larger number
48
thermosets- forces between chains
strong covalent bonds
49
thermosets- response to heat
degradation and decomposition
50
thermosets- hardness
generally hard
51
biodegradable
| not to be confused with compostable
ability to decompose in the environment
## Footnote
within a given time frame (~80 years is a good ballpark)
52
bioplastics
plastics produced from biomass
53
carbon negative
describes a process that absorbs more carbon dioxide than it produces
54
chemolysis
the use of solely chemical substances to decompose organic substances into simpler ones
55
circular economy
A continuous cycle that focuses on the optimal use and re-use of resources from the extraction of raw materials through to production of new materials, followed by the consumption and re-purposing of unused and waste materials
56
compostable
Describes a polymer that can be at least 90% decomposed after 180 days in a composting environment
57
dehydrate
To remove Hâ‚‚O from a molecule or ion
58
dehydrogenate
To remove a hydrogen atom or atoms from a molecule or ion
59
feedstock
raw material used for producing another product
60
greenhouse gases
molecules that absorb infrared radiation from the sun
61
humus
dark, nutrient-rich, organic material produced from composting
62
linear economy
Operates on a 'take-make-dispose' model, making use of resources to produce products that will be discarded after use
63
plastic dissolution
dissolving plastic to extract polymers and separate them from their additives
64
pyrolysis
decomposition brought about by high temperatures
65
steam cracking
The breaking down of larger saturated hydrocarbons into smaller, often unsaturated ones
66
how is ethene produced
via steam cracking- larger hydrocarbons extracted from crude oil, are mixed with steam and heated in the absence of oxygen to produce small, unsaturated hydrocarbons.
67
what is HDPE used in
milk jugs, detergent bottles, outdoor furniture
68
what is LDPE used for
plastic bags, food wraps
69
PVC
aka vinyl
widely used plastic made up of chloroethene/vinyl chloride monomers
chloroethene monomers are synthesised by reacting chlorine gas with ethene which is produced from crude oil in steam cracking
70
what is PVC used for
pipes, electrical cable insulation, vinyl records
71
PP
plastic composed of propene monomers that are produced via steam cracking
72
PP applications
flexible, rigid packaging, rugs, bags, cars
73
PS
distinctive plastic made of styrene monomers
ethyl benzene is dehydrogenated and then polymerised
74
PS application
as it is soft and lightweight, it is suitable for usage in packaging, polystyrene cups and insulated boxes
75
PLA
polylactic acid is a condensation polymer produced from fermented plant starch from crops like sugarcane or corn
76
PLA properties
low melting point
high strength
good adhesivity
most widely used filament plastic in 3d printing- also used in disposable cutlery
77
bio PE
bio polyethene/renewable polyethene has the same formula as HDPE and LDPE but is deribed from plants
78
how is bio PE produced
crops are fermented to produce ethanol which is then dehydrated to form ethene and polymerised and can be produced as LDPE or HDPE
79
bio PE environmental impacts
crops used to produce bio PE like wheat and sugar cane, absorb carbon dioxide making its production carbon negative, reducing greenhoue gas emissions
howver, it requires a large area and rapid harvesting can cause land degradation
80
bio PP
bio polypropene is primarily produced from crops or vegetable oils
81
production of bio pp from crops
fermentation (methylpropan-1-ol)
dehydration (methyl propene)
various methods (propene)
addition polymerisation (polypropene)
same manufacturing equipment can be used
82
recycling codes
1- PETE
2- HDPE
3- PVC
4- LDPE
5- PP
6- PS
7- other
83
mechanical recycling process
collection
sorting
cleaning
shredding
melting
reforming
repurposing
84
can thermosets be recycled
in general they can't but all thermoplastics can be mechanically recucled
85
products of mechanical recycling
usually only used for lower grade plastic products due to hte risk of toxic contamination and some plastics like PVC are more difficult and resource intensive to recycle than others and so not all recycling facilities consider recycling worthwhile
86
chemical recycling
aka advanced or feedstock recycling involves converting plastics back into either constituent polymers, monomers or organic chemicals
87
how can chemical recycling occur
plastic dissolution- heating plastics with solvents to produce a solution of polymers and additives that can be separated
chemolysis- depolymerising plastics breaking it up into its constituent monomers- only used for condensation plymers
pyrolysis- convert plastics to raw organic chemicals which can then be used as fuels to produce energy- prohibitvely expensive
88
chemical recycling methods and products- conversion
methods: conversion
- gasification, pyrolysis, hydrothermal, hydrocracking
products
- refined hydrocarbons give you petrochemicals or fuels -> monomers -> polymers -> plastic products
89
chemical recycling methods and products- polymerisation
methods:
enzymolysis
chemolysis
solvolysis
products
monomers -> polymers -> plastic products
90
chemical recycling methods and products- purification
method:
dissolution
products
polymers -> plastic products
91
compostable plastics
biodegradable in a short time period without leaving any toxic residue or microplastics only nutrients
92
process of degrading compostable plastics
bacteria in a composter struggles to break down the polymer chains- so it is first shredded
reacted with water at high temperatures to break it down into its constituent monomers
bacteria decompose the monomers to produce water vapour and CO2- released into environment as well as humus
high temperature environments of an industrial composter to break down rapidly - in these composting environments, moistre, oxygen and heat levels are carefully controleld to ensure maximal breakdown rate
93
examples of compostable bioplstics
PLA and PHB (polyhydroxylbutyrate)- produced when microorganisms are stressed
PHB can be used for internal stitches as it is non toxic
94
fossil fuel based plastic that is compostable
PBAT- polybutylene adipate terephthalate is tough and flexible that can be used to make cling wrap
95
current barriers to plastic recycling
25%- of thermoset plastics cant be recycled
recycling is expensive and buyers of recycled plastics are hard to find
insufficient recycling facilites- shipped overseas prior but this is now banned
incineration is cheaper- produces toxic emissions
only 9% is actually recycled
96
potential circularity of chemical recycling
monomers
polymerisation
high grade plastic
chemical recycling
monomers
97
condensation polymerisation
chemical reaction between monomers resulting in the formation of a polymer and water
98
hydrolysis
reaction involving the cleavafe of bonds using water to break up polymers into monomers
99
innovation
introduction of new methods, procedures or products to traditional industries
100
in condensation polymerisation what reacts
alcohol with another functional group, often a carboxylic acid to form a covalent bond bewteen molecules, simultaneously releasing a water molecule
101
uses of PLA
as it can be degraded into lactic acid, it is useful in the construction of medical implants like screws or plates as it can remain intact for up to 2 years during a healing process before being broken down and naturally removed
102
condensation polymerisation for PBS- polybutylene succinate
monomer succinic acid (COOH functional group) + monomer 1,4 butanediol (OH functional group)
-> polybutylene succinate + water
103
what makes polymers biodegradable
as condensation reactions produce water, due to he rearrangement of oxygen and hydrogen atoms from functional groups into water molecules- the functional groups are left in a reactive state
when water is reintroduced to the polymer system- the reaction occurs in reverse, through hydrolysis
104
polymer circular economy
renewable resource
industrial processing plant
biodegradable polymer product
biowaste bin
specific biowaste collection
biowaste treatment composting plant
fertiliser
back to a renewable source
105
how does stronger intermolecular forces impact the properties of the polymer
increase hardness and rigidity of the polymer
increase melting point or density as they are held together tightly
106
3 ways bioplastics can be recycled
chemical- polymer to monomers to raw chemicals
mechanical- shred, melt, reform
organic- composters
107
difference between natural and synthetic polymers
Natural polymers are created in the environment, for example, by plants or animals.
synthetic polymers are man-made through manufacturing processes.
108
