Transcript Properties of plastics PowerPoint

* Starter
(Nat 5 2014)
C
A
D
*Learning
Intentions:
•
•
Give examples of natural and synthetic fibres.
•
•
•
•
State synthetic materials are made by the chemical industry.
State most plastics and synthetic fibres are made from chemicals
derived from oil.
Explain the terms ‘thermosetting’ and ‘thermoplastic’.
Explain the problems with some plastics.
Name examples of plastics including polythene, polystyrene etc. and
give their uses.
*Plastics
* Natural
and
Synthetic Fibres
*Plastics are widely used as they have many
useful properties e.g. lightweight (low
density) and waterproof. They are good heat
insulators and also good electrical insulators.
*Plastics and synthetic fibres are man-made
materials, this is why they are called
SYNTHETIC.
*In addition, plastics are easily moulded into a
variety of shapes and are excellent
insulators of both heat and electricity.
COTTON
From fibres of the cotton plant.
WOOL
From spun hair of sheep.
LINEN
Made from fibres of a plant called
.
SILK
Made from fibres produce by
.
*Properties
of Plastics
Page 2 of pupil booklet
*Most plastics and synthetic fibres are made
crude oil
from chemicals derived from ____________
and are made up of long chain molecules called
polymers.
*Plastics are examples of polymers - very large
molecules formed by the joining of many small
monomers
molecules called __________.
NYLON
Used to make jackets, sports bags,
sportswear and ropes.
POLYESTER
Used to make trousers, shirts, sportswear.
Some polyester clothes are labelled
TERYLENE.
POLYTHENE
Used to make bags, packaging,
containers, food boxes.
Nylon
Nylon widely known as a fibre. Nylon as a
plastic, is widely used in machine parts, as
it is very strong.
PERSPEX
Used as replacement for glass but not
as brittle as glass. Can easily be
shaped. Used to make jewellery.
POLYPROPYLENE (POLYPROPENE)
As a fibre used to make ropes and
carpets. As a plastic it is used to make
containers, packaging and combs.
POLYVINYL CHLORIDE (PVC)
Used as floor covering, window frames, electrical
insulation and water pipes.
POLYSTYRENE (Expanded)
Used in packaging as it is light and absorbs
knocks. It is a good heat insulator and is
used in take-away food cartons.
POLYSTYRENE (Non-expanded)
This is a rigid plastic and is used to make
casings for TV’s, computers, cameras.
*Effect
of Heat on Plastics
*
Page 2 of pupil booklet
* Some plastics soften when heated and can be
reshaped whereas others cannot.
*Thermoplastic:
A plastic which softens on heating and
*____________________________________
can be reshaped e.g. P.V.C. and polythene.
__________________________________
*Thermosetting:
A plastic which does not soften
*____________________________________
on heating e.g. bakelite and formica.
________________________________
* Problems
Plastics
with
Page 2 of pupil booklet
*Plastics are not biodegradable. This means they do not…
rot away naturally by biological processes.
_____________________________________
*Incomplete
Combustion of Plastics
*The poisonous gas produced on incomplete burning of
Carbon monoxide
plastics is called: ____________________
*Disposal
of Plastics
*Plastics can be disposed of by burying, incineration
or recycling.
* Naming
Polymers
Page 3 of pupil booklet
* The name of the polymer comes from the name of the monomer
used to make it e.g. the monomer ethene can be used to make the
polymer poly(ethene).
* Notice how the prefix poly- is put in front of the name of the
monomer. Brackets are put around the name of the monomer.
Monomer
Polymer
Use
propene
poly(propene)
Packaging and labelling, textiles,
stationary
phenylethene
poly(phenylethene)
vinyl chloride
ethene
styrene
Domestic appliances, medical
applications
poly(vinyl chloride) also Electrical cable covering and frames
known as PVC
poly(ethene) also known
as polythene
poly(styrene)
for double- glazed windows
Carrier bags
Packaging, drinking cups and CD/
DVD cases
* Starter
(Nat 5 2014)
B
B
*Learning
Intentions:
•
State what is meant by: monomer, polymer and polymerisation.
•
To state that addition polymers are made from small unsaturated
molecules, produced by cracking, by a process called addition
polymerisation.
•
Describe addition polymerisation as small unsaturated molecules
joining together by the opening of the carbon to carbon double bond.
•
Draw the structure of an addition polymer given the monomer
structure, or the repeating unit / monomer given the polymer
structure.
* Polymerisation
Page 4 of pupil booklet
*
Polymerisation is the process in which
the small monomer units __________
join
together to form a large polymer
molecule.
*POLYMERISATION
Plastics and synthetic fibres
are made from giant
molecules.
Monomer
molecules
join
together
Small part
of a
polymer
molecule.
Joining together many thousands
of smaller molecules called
MONOMERS makes these giant
molecules.
The giant molecule is called a
POLYMER as joining many small
molecules together makes it. POLY
means many.
* Addition
Polymerisation
Page 4 of pupil booklet
*Addition polymerisation is a process involving many
small, __________
unsaturated monomers combining to form one
large polymer molecule.
*The alkenes, ethene and propene are two important
feedstocks in the petrochemical industry which can
also be used to make addition polymers.
*Addition polymers are made from monomers that
contain a –C=C– double bond and result in a polymer
‘backbone’ made solely of ______atoms.
carbon
H
H
C C
H
H
One of the covalent bonds of the C=C
breaks open, allowing the monomers to
“ADD” to each, other building up the
polymer chain.
*Formation
of poly(ethene)
The most common monomer is ethene, C2H4.
H
H
H
H
H
3 ethene
C C
C C
C
molecules
MONOMERS H
H
H
H
H
The joining up reaction is called
ADDITION POLYMERISATION
as a polymer is made.
A section of the
POLYMER. The
polymer is named by
placing POLY in front
of the monomer name.
H
C
H
The C=C breaks open allowing the
molecules to join.
H
H
H
H
H
H
C
C
C
C
C
C
H
H
H
H
H
H
(also known as polythene)
*Formation
of poly(propene)
Addition
polymerisation
Propene monomers (x 3)
Double bonds break
The repeating unit
for polypropene is…
poly(propene) is formed
All addition polymers have a chain
of C–C single bonds forming the
backbone of the polymer molecule.
Animation
For each of these monomers, draw a section of the polymer
produced when 3 molecules of each monomer above join.
Name each polymer produced.
This group of atoms is
called the phenyl group.
H
CH3
H
H
Propene
F
C C
C C
H
C6H5
H
F
C C
H
Phenylethene
(styrene)
F
F
Tetrafluoroethene
*
Page 6 of pupil booklet
If the structure of the polymer is given then the
structure of the monomer can be worked out.
* The repeating unit
* Closing the double bond
gives the monomer
* Starter
(Nat. 5 2014)
Starter answers
(Nat. 5 2014)
*Learning
Intentions:
•
To revise our previous knowledge of condensation
reactions from Unit 2; forming esters.
•
State that condensation polymers are made from
monomers with two functional groups per molecule.
•
Draw the structure of a polyester polymer given the
monomer structures.
•
Draw the repeating unit / monomers given the polymer
structure.
* Condensation
Polymerisation
Page 7 of pupil booklet
*Condensation
Reactions
In unit 2 we learned that esters molecules are formed by condensation
reactions.
alcohol
+
carboxylic
acid
propan-1-ol
+
ethanoic
acid
H H H
H
C C C O H
H H H
+
C
C
H
water molecule
eliminated
CH3CH2CH2OH
+
propyl
ethanoate
H
O
H O
ester
HOOCCH3
H H H
H
H
C C C
H H H
O
O
H
C
C
H
+
water
+
water
+
O
H
H
ester link
(carboxylate group)
CH3CH2CH2OOCCH3
+
H2O
H
*Condensation
Polymerisation
*Condensation polymerisation is a process
whereby many small monomer molecules
join together to form one large polymer,
water or some other small molecule
with _____,
(e.g. HCl) formed at the same time. The
monomers have more than one functional
group (-OH, -COOH, -NH2).
*Polyesters
*Polyesters are examples of condensation
polymers formed by the reaction between a
diacid with a diol. Both monomers must have
____
two functional groups (one at each end of the
molecule).
DICARBOXYLIC ACID
Dialcohol
(Diol)
(Diacid)
MONOMERS
of a
POLYESTER
H O
O H
O
H O C
O
C O H
* Making
O
H O
O H
O
O
H O
C O H
H O C
H2O
molecule
forms
H2O
molecule
forms
The polymer
molecule contains
many ester links,
hence the name
POLYESTER.
a Polyester
O H
H O C
O
C O H
H2O
molecule
forms
Condensation polymerisation
O
O
O
C O
O C
Ester link
Ester link
O
O
O C
C
Ester link
The structure of the polyester molecule repeats every TWO MONOMERS.
This is called the REPEATING UNIT.
O
O
O C
O
C O
REPEATING UNIT
O
O
O C
C
* MAKING
TERYLENE - A POLYESTER
DICARBOXYLIC ACID
DIALCOHOL
O
H H
H
O
H O C
C C O H
H H
H
O
C C O H
C O H
benzene-1,4-dicaboxylic acid
(other name: terephthalic acid)
ethane-1,2-diol
O
H H
O
O
H O C
O
H H
H
C O H
O
H H
C C O H
H O C
O
C O H
H H
H2O
O
H2O
H2O
Condensation polymerisation
H H
O
O
C C O
C
C
H H
O
H H
O
O
C C O
C
C
POLYESTER
H H
REPEATING UNIT
O
H H
O
O
C C O
C
C
H H
n
*Breaking
a Polyester
(Page 8 of pupil booklet)
*If you are asked to identify the monomers
from a condensation polymer, simply add a
water molecule back across the ester link.
This is called ________.
hydrolysis
*To break the ester link, firstly identify
the ester link and then just add water.
*A polyester
undergoes hydrolysis
with the addition of
water to create a
diacid
diol and a _____.
____
*In summary…
*During hydrolysis, water
attacks the ester link and
adds across it.
*Adding water across the
ester link produces a
carboxylic acid and an alcohol.
*Polymer
backbones
*The 'backbone' of a polymer can tell us
whether it is an addition polymer or a
condensation polymer.
*A horizontal chain can be seen in the polymer
below [poly(ethenol)]:
*This polymer only has carbon atoms in it's backbone.
*This indicates that the molecule was formed by
addition polymerisation.
_______
*The polymer below (Kevlar) has a more
complicated backbone.
*This backbone includes atoms of carbon and
nitrogen.
*If the polymer backbone has any atom other
than carbon in it (such as nitrogen or oxygen),
then it was formed by ___________
condensation
polymerisation.
* Starter
(Nat. 5 Specimen)
A
B
*Learning
Intentions:
•
Revise that carbohydrates are compounds containing the
elements carbon, hydrogen and oxygen only.
•
State that starch is a natural condensation polymer made
of many glucose molecules linked together.
•
Understand the classifications mono-, di- and
polysaccharides in relation to the terms monomer and
polymer.
•
Describe the tests for starch.
* Natural
Polymers
Page 10 of pupil booklet
*Polymers are not simply an invention of
chemists. Many are synthesised in nature
and even in our bodies. The most common
natural polymers are carbohydrates like
starch and cellulose, and proteins.
Carbohydrate
Cellulose
*Carbohydrates
*Plants make carbohydrates which are high energy
foods containing the elements carbon, hydrogen, and
oxygen.
*They do this by the method of photosynthesis.
*While they produce glucose (a monosaccharide sugar)
during photosynthesis, they store this as starch (a
polysaccharide) which is formed by linking together
many monosaccharide units within the plant.
carbon dioxide + water
6CO2 + 6H2O
𝑙𝑖𝑔ℎ𝑡 𝑒𝑛𝑒𝑟𝑔𝑦 𝑎𝑛𝑑 𝑐ℎ𝑙𝑜𝑟𝑜𝑝ℎ𝑦𝑙𝑙
𝑙𝑖𝑔ℎ𝑡 𝑒𝑛𝑒𝑟𝑔𝑦 𝑎𝑛𝑑 𝑐ℎ𝑙𝑜𝑟𝑜𝑝ℎ𝑦𝑙𝑙
glucose + oxygen
C6H12O6 + 6O2
Starch and cellulose (carbohydrates) are natural
condensation polymers.
All carbohydrates are based on the
monomers glucose or fructose
(C6H12O6).
These carbohydrates are classified as
MONOSACCHARIDES.
A monosaccharide
can be represented
as:
C6H12O6
When 2 monosaccharides join a disaccharide is produced
and a water molecule is lost.
2 monosaccharides
+
C6H12O6
C6H12O6
disaccharide
C12H22O11
+
H2O
When many monosaccharides join a polysaccharide is
produced and many water molecules are lost.
many monosaccharides
+
+
n C6H12O6
H2O molecule is lost from
each C6H12O6 making the
polymer chain made of many
C6H10O5 units.
(C6H10O5)n
polysaccharide
+
n H2O
many water
molecules
n = a large
number
Starch and
cellulose are
polysaccharides.
*Testing
for Starch
* Physical test
* The Tyndall Beam experiment can be used to distinguish
starch from glucose by shining a beam of light through
'solutions' of each.
* Dispersal only happens in starch as the large starch molecules
are big enough to affect the light and disperse it.
* The light will pass straight through the solution of glucose.
* Chemical test
* In the presence of starch, iodine changes from yellow/brown
to a blue/black colour. It is possible to distinguish starch from
other carbohydrates using this iodine solution test.
* For example, if iodine is added to a peeled
potato then it will turn black.
*Digestion
of Starch
*During digestion starch is broken down into glucose.
Glucose is small enough to pass through the gut wall but
starch cannot. This is done in the lab using dilute acid; or
in the body using enzymes (biological catalysts). The main
enzyme for digestion is amylase. Enzymes work best at
body temperature (37oC).
*Water must be added which is the reverse of
condensation polymerisation. This is known as hydrolysis.
*Hydrolysis is when one large molecule is broken down into
smaller molecules by reaction with water.
O-
G
-O
O-
G
-O
O-
G
-O
+H2O
HO-
G
-OH
+
HO-
G
-OH
+
HO-
G
-OH
*Proteins
(Page 12 of pupil booklet)
*Nitrogen is an essential nutrient for all plants
and animals, as it is needed to make proteins.
*Proteins are natural __________
condensation
polymers
formed by joining together thousands of amino
acid molecules.
*Amino acids have two functional groups; a
carboxyl group and an amine group.
*Amino
acids
• The monomers of proteins are amino acids.
• There are 20 amino acids used to make proteins. The
different amino acids have the same basic structure,
with the R group being different. Here are three
amino acids.
CH
CH OH
2
3
H H O
H N C C O H
H
glycine
O
H
H N C C O H
H
alanine
O
H
H N C C O H
H
serine
*Protein
formation
Two amino acids combine in a condensation reaction to
form a protein and a water molecule.
CH3
CH2OH
O
O
H H O
H
H
H N C C O H
H
H N C C O H
H2O molecule
forms
H
H N C C O H
H2O molecule
forms
H
Condensation polymerisation
Part of a
PROTEIN
molecule.
CH2OH
CH3
O
O H H O H
H
N C C N C C N C C
H peptide linkH peptide link H
H O
In a protein the N C
is called a PEPTIDE
LINK.
Each protein has its own sequence of amino acids making up the polymer chain.
*Proteins
in the body
*Proteins have many important jobs within
the body. They form the major structural
materials of animal tissue including hair,
nails and muscle etc. Other proteins are
involved in regulating life processes. These
include haemoglobin, enzymes and certain
hormones like insulin.
*Digestion
of proteins
*During digestion the proteins we eat are
broken down into _____
amino acids (by hydrolysis).
*These amino acids are transported around the
body by blood. In the bloodstream,
condensation reactions build the amino acids up
to produce proteins required by the body.
* Starter
(2014 P.P.)
D
B
*Learning
Intentions:
•Give examples of new polymers with special properties and
their uses.
* Novel
Materials
Page 14 of pupil booklet
*A novel material is a new material; one that
does not resemble anything that was
previously known or used.
*A smart material is one that changes shape
in response to changes in its environment
*Hydrogels are smart materials that have
found a lot of uses in daily life because
they are polymers that absorb _____.
water
*Hydrogels
(Polyacrylate)
*The first hydrogels were used in the 1950s to develop
early contact lenses and many different types have now
been developed.
*In simple terms they are all insoluble substances that
form a tangled, three-dimensional network of fibres.
*When a gel is in contact with water,
functional groups along the fibres
(carboxyl, -COOH groups) ionise
(become charged) and the negative
charges repel each other, forcing
the fibres to become less tangled
and to expand.
*Water is a polar molecule (slightly
charged) and is attracted to the negative
charges that exist within the structure.
This is why water is absorbed.
Hydrogel
experiment
*Uses
of Hydrogels
A hydrogel polymer is used in disposable
nappies.
Plant storage crystals are hydrogels. They
absorb water and swell up. If put in plant tubs
and hanging baskets they slowly release water
extending the time between watering's, for
example when you go on holiday.
Soft contact lenses are hydrogels. Their ability
to absorb water means they don’t dry out in use,
and are compatible with tears which lubricate
the eye making them more comfortable to wear.
*More
Novel Materials
*Polyvinyl
Alcohol (PVA)
Polyvinyl alcohol (PVA) is a watersoluble polymer. It is used as an
adhesive.
As a film it is used to make the
packaging of “liqui-tabs”, which hold
detergent for dishwashers and
washing machines.
*Kevlar
*Kevlar is a condensation polymer. It is very
strong but also very light and can therefore
be used aircraft wings, bulletproof vests and
other products where strength and weight
are important.
*Polyethenol
*This plastic is soluble in water and can
therefore be used to make laundry bags
and surgical stitches.
*Conductive
Plastics
*Most plastics are insulators.
*However, specific polymer materials like
polyaniline, polythiophene and polypyrrole
have been developed and can conduct
electricity for the development of flexible
touch screens etc.
*One of the earliest conducting polymers to
be developed was polypyrrole.
*Colour
changing plastics
*Packaging that incorporates nanomaterials can be
“smart,” which means that it can respond to
environmental conditions or repair itself or alert a
consumer to contamination and/or the presence of
pathogens.
*These can be used in food packaging to let
consumers know the condition of the food.
Colour changing disposable beverage lids showing
increasing redness from left to right.
*Bioplastics:
Polylactic acid (PLA)
Bioplastics are polymers made from plant
sources.
Starch-based plastics currently
represent the mostly widely used
bioplastic. Protective packaging is an
example of this type of polymer.
Polylactic acid (PLA) is made from corn
or sugar cane. It is used to make
disposable cutlery, waste sacks and
sutures used for internal stitches in the
body during surgery.
Bioplastics are biodegradable.
*Exercise:
1.
Poly(ethenol) is a water soluble plastic that has many uses from
laundry bags to dishwasher tablets.
a)
b)
2.
Properties of plastics
Plastics are synthetic. What is meant by the term ‘synthetic’?
When heated, poly(ethenol) softens and can be reshaped. What
name is given to such plastics?
Styrene, which is also known as phenylethene, can be extracted
from the sap of the styrax tree. Styrene is the monomer used to
produce polystyrene.
a)
b)
Name the type of polymerisation that takes place to form
polystyrene.
Draw a section of the polystyrene polymer showing three
monomer units combined.
3.
Poly(butene) is an addition polymer made up of butene, C4H8,
monomers.
a)
Draw a section of poly(butene) showing three monomer units
joined together.
b)
Draw the repeating unit for poly(butene).
4.
The structure for part of the poly(chloroethene) polymer chain is:
a)
b)
c)
d)
Draw the structure of its repeating unit.
Draw the structure of the monomer unit.
Name the monomer unit.
Find out the common name for poly(chloroethene).
5.
Poly(lactic acid) is made from the monomer lactic acid which has the
structural formula shown:
a)
Rearrange the molecule above so that there is a hydroxyl group at
either end of this molecule.
b)
c)
Use your rearranged molecule to draw a section of poly(lactic acid)
showing three monomer units linked together. [HINT: the
monomers will be joined by ESTER links]
State the type of polymerisation that poly(lactic acid) is formed by.
6.
Part of the structure of Kevlar is shown:
Draw the structures of the two monomers used to make Kevlar.
*Exercise:
1.
2.
Novel materials
a)
b)
What is a smart material?
c)
c) Name two natural polymers.
A hydrogel is a smart material; give one common use for
hydrogels.
PVC is a very useful plastic. It can be used to make window frames
and to make the insulating cover for electrical cables. PVC is not
biodegradable.
a)
b)
What is meant by the term biodegradable?
Why have biodegradable polymers been developed?