MOLECULAR ORIGIN OF POLYMER PROPERTIES Flashcards
These small units are repeated
throughout the macromolecule
chain
POLYMERS
macromolecule or long molecules
POLYMERS
built of small
covalently bonded units called
monomers
POLYMERS
Greek word for part
“mer” from meros
▪ The macromolecules are bonded
together by
weak Van der Waals
and hydrogen (secondary) bonds,
or additional covalent crosslinks
repeating unit of (image p3)
polyethylene (PE)
poly
many
mer
repeat unit
repeating unit of (image p3)
polyvinyl chloride (PVC)
repeating unit of (image p3)
polypropylene (PP)
(image p4) commodity thermoplastics
polypropylene
(image p4) commodity thermoplastics
polyacetylene
(image p4) commodity thermoplastics
poly(p-phenylene vinylene)
(image p4) commodity thermoplastics
polythiophene
(image p4) commodity thermoplastics
polyphenylene sulfide
(image p4) commodity thermoplastics
polyanilines
(image 5) biomedical applications
polycarbonate (diphenyl carbonate)
(image 5) biomedical applications
polymethyl methacrylate
(image 5) biomedical applications
silicone polymers
(image 5) biomedical applications
polyvinylidene chloride
(image 5) biomedical applications
polyindene
(image 5) biomedical applications
polyvinyl pyrrolidone
(image 5) biomedical applications
coumarone polymer
Most polymers are _________, and formed from __________ molecules
organic , hydrocarbon
no. electrons in each C atom that participate in covalent bonding
4 electrons
no. bonding electron/s in each H atom
1 bonding electron
A single covalent bond exists when
each of the two bonding atoms contributes one
electron
involve the sharing of two and
three pairs of electrons
Double and triple bonds
Molecules that have double, and triple covalent bonds are termed
unsaturated
each carbon atom is not bonded to the maximum (four) other atoms
unsaturated (double, and triple bonds)
all bonds are single ones
a saturated hydrocarbon
no new atoms may be
joined without the removal of others that are already bonded
a saturated hydrocarbon
(image 7)
Methane , CH4
(image 7)
Ethane , C2H6
(image 7)
Propane , C3H8
(image 7)
hydrocarbon ethylene , C2H4
(image 7)
acetylene , C2H2
molecule that combines with other molecules of the
same or different type to form a polymer
monomer
The structure of the repeating unit of a polymer is essentially that or
_____________ to that of the ____________ molecule(s).
closely related , monomer
monomer for polyacrylonitrile
Acrylonitrile, CH2=CHCN
(image 8)
Acrylonitrile, CH2=CHCN
Monomer for polyethylene
Monomer for polyvinyl chloride
Monomer for polyisobutylene
Monomer for polystyrene
Monomer for polycaprolactam (6-nylon)
Monomer for polyisoprene (natural rubber)
a low-molecular-weight polymer. It contains at least two monomer units
oligomer
oligomer of polyethylene
hexatriacontane
(image 10)
hexatriacontane
ethylene gas is reacted under appropriate conditions, it will transform to
polyethylene (PE) , solid polymeric material
transformation of ethylene gas to
polyethylene (PE) begins when
an active center is formed by the reaction between an initiator or catalyst species (R.)
and the ethylene monomer
an active center is formed by the
reaction between an initiator or catalyst species (R.)
and the ethylene monomer
(image 11)
formation of an active center
The polymer chain then forms by the ____________ of monomer units to this
actively growing chain molecule.
sequential addition
repeat unit of polymer (image 12)
polytetrafluoroethylene (PTFE)
repeat unit of polymer (image 12)
polystyrene (PS)
repeat unit of polymer (image 13)
poly(methyl methacrylate)
PMMA
repeat unit of polymer (image 13)
phenol-formaldehyde (bakelite)
repeat unit of polymer (image 13)
poly(hexamethylene adipamide)
nylon 6,6
repeat unit of polymer (image 13)
poly(ethylene terephthalate)
PET, a polyester
repeat unit of polymer (image 13)
polycarbonate (PC)
specifies the length of the polymer molecule.
degree of polymerization
subscript designation, n, indicates the
number of repeating units strung
together in the polymer chain (molecule).
______________ normally required for a material to develop useful properties and before it can be appropriately described as a
polymer.
high degree of polymerization
dimensionless quantity given by the sum of the atomic weights in the molecular formula.
Molecular weight
equation for relation between degree of polymerization and molecular weight M of the same macromolecule
M = (DP)Msubs0
FIVE CLASSIFICATION
BASED ON
- origin
- polymer structure
- polymerization mechanism
- thermal processing behavior
- preparative technique
CLASSIFICATION OF POLYMERS BASED ON ORIGIN
NATURAL VS. SYNTHETIC
Wood, rubber, cotton, leather, wool, silk, protein, enzymes, starches, cellulose
natural polymers
Synthetic Polymers
✓ Fibers, elastomers, plastics, adhesives
CLASSIFICATION BASED ON POLYMER STRUCTURE
A. LINEAR, BRANCHED OR CROSS-LINKED, NETWORK VS.
FUNCTIONALITY
B. AMORPHOUS OR CRYSTALLINE
C. HOMOPOLYMER OR COPOLYMER
D. FIBERS, PLASTICS, OR ELASTOMERS
CLASSIFICATION BASED ON POLYMERIZATION
MECHANISM
CONDENSATION POLYMERS
ADDITION POLYMERS
CLASSIFICATION OF POLYMERS ACCORDING TO
THERMAL PROCESSING BEHAVIOR
▪ THERMOPLASTICS
▪ THERMOSETS
CLASSIFICATION BASED ON PREPARATIVE TECHNIQUE
▪ BULK POLYMERIZATION
▪ SOLUTION POLYMERIZATION
▪ SUSPENSION POLYMERIZATION
▪ EMULSION POLYMERIZATION
BULK PROPERTIES OF POLYMERS
▪ TENSILE STRENGTH
▪ YOUNG’S MODULUS OF ELASTICITY
▪ TRANSPORT PROPERTIES
▪ PURE COMPONENT PHASE BEHAVIOR
its interlinking capacity, or
the number of sites it has available for bonding with other
molecules under specific polymerization conditions.
FUNCTIONALITY
under FUNCTIONALITY, a molecule may be classified ________________, ___________ and ____________ depending on whether it has one, two, or greater
than two sites available for linking with other molecules.
monofunctional, bifunctional, or
polyfunctional
those in which the
repeat units are joined together end to
end in single chains
✓Linear polymers
These long chains
are flexible and may be thought of as a
mass of “spaghetti.”
✓Linear polymers
Some of the common examples of
linear polymers are
polyethylene, PVC,
polystyrene, and polyamides.
_________ polymers are generally more
rigid
linear
have side chains or branches
growing out from the main chain
▪ BRANCHED POLYMERS
The side chains or
branches are made of the _______________ as the
main polymer chains.
same repeating units
For a polymer to classify as branched polymer the side
chains or branches should comprise of a minimum of ____________
one complete monomer unit
One of the most common example branched
low-density
polyethylene (LDPE)
applications ranging from
plastic bags, containers, textiles, and electrical insulation, to coatings for packaging materials
low-density polyethylene (LDPE) , branched polymers
adjacent linear chains are joined one to another at various positions by covalent bonds
crosslinked polymers
tend to be permanent in
nature
Crosslinks
Once the crosslinks between the
chains develop the polymer then
becomes _______
thermoset.
✓Common examples include
Bakelite,
melamine, epoxies, bulk molding
compounds, rubber, and various
adhesives.
Multifunctional monomers forming
three or more active covalent bonds
make three-dimensional networks
network polymers
These materials have distinctive
mechanical and thermal properties
network polymers
network polymers
epoxies, polyurethanes, and
phenol-formaldehyde
the material
exhibits organized and tightly packed molecular
chains
CRYSTALLINE
they have good strength &
wear, and good chemical resistance, but they typically lack in impact resistance.
CRYSTALLINE
✓Examples of crystalline polymers include
polyethylene, polyacrylonitrile, poly(ethylene
terephthalate), and polytetrafluoroethylene
polymers that have no
crystalline regions and no uniformly packed
molecules
Amorphous polymers
composed of amorphous regions where molecules
are randomly arranged.
Amorphous polymers
good examples of amorphous polymers
✓Natural rubber latex and styrene-butadiene rubber
(SBR)
measure of the degree of order or
orientation in a crystal.
degree of crystallinity
ranges from 0 to 100%, where 0% represents
an amorphous material, and 100% represents a perfectly crystalline
material.
degree of crystallinity
degree of crystallinity by ___________ may be determined from accurate
density measurements, according to
weight , (image 25)
1, WATER BOTTLES, JARS, CAPS
PET (POLYETHYLENE TEREPHTHALATE)
2, SHAMPOO BOTTLES, GROCERY BAGS
HDPE (HIGH-DENSITY POLYETHYLENE)
3, CLEANING PRODUCTS, SHEETINGS
PVC (POLYVINYL CHLORIDE)
4, BREAD BAGS, PLASTIC FILMS
LDPE (LOW DENSITY POLYETHYLENE)
5, YOGURT CUPS, STRAWS, HANGER
POLYPROPYLENE
6, TAKE-AWAY AND HARD PACKAGING TOYS
POLYSTYRENE
7, BABY BOTTLES AND NYLON CDS
OTHERS
(IMAGE 33)
condensation polymerisation
✓When all of the repeating units along a chain are of
the same type, the resulting polymer is called a
homopolymer.
✓The purpose of homopolymers is to produce a
polymer that has
increased mechanical properties.
These enhanced mechanical properties include:
tensile strength, stiffness, impact resistance, and
short-term creep resistance.
increased mechanical properties enhanced
tensile strength, stiffness, impact resistance, and
short-term creep resistance.
example of homopolymers
polyvinyl chloride
polyethylene
polypropylene,
polycarbonate
polyester
nylon 6
nylon 11,
polytetrafluoroethylene
styrene
polymer made up of more
than one type of monomer unit.
COPOLYMER
Copolymers are produced by polymerizing
two or more types of monomer together in
a process referred to as
copolymerization.
The purpose of creating a copolymer is to
manufacture a polymer with
more desirable
properties
Copolymers typically experience
a
lower crystallinity
higher glass transition
temperature
improved solubility
to get Buna-S, copolymerization happened between
1,3-butadiene and Styrene
to get Nylon 6,6, copolymerization happened between
Hexamethylenediamine and Adipic acid
ABBABBBAABBAABAAABBA
two different mers by A and B, a random copolymer
the two mers
alternate in a regular fashion along the polymer chain
alternating copolymer
-ABABABABABABABABABAB-
alternating copolymer
-AAAAAAAAAABBBBBBBBBB-
block copolymer
a linear polymer with one or more long
uninterrupted sequences of each mer in the chain
block copolymer
a branched
copolymer with a backbone of one type of mer and
one or more side chains of another mer
graft copolymer
(image 29)
graft copolymer
(image 29)
- random
- alternating
- block
- graft
linear polymers with high
symmetry and high intermolecular forces
that result usually from the presence of polar groups
✓Fibers
characterized by high modulus, high
tensile strength, and moderate extensibilities
✓Fibers
Examples of fibers are
Polyester
Nylon,
Terelyne
Spandex
Kevlar
Rayon
Acetate
Acrylic
Lastex
Polypropylene
molecules with
irregular structure, weak
intermolecular attractive forces, and
very flexible polymer chains.
elastomers
Elastomers are polymers that have
viscosity and elasticity and therefore
are known as
viscoelasticity.
polymers that have
viscosity and elasticity
Elastomers
inherit the unique property of
regaining their original shape and
size after being significantly
stretched
Elastomers
Examples of elastomers are
rubber
polyurethanes
polybutadiene
a polymer, typically
modified with
additives, which can
be molded or
shaped under
reasonable
conditions of
pressure and
temperature
plastic
commonly used in commercially sold water bottles, soft drink bottles, sports drink bottles, and
condiment bottles.
1 PET, Polyethylene terephthalate
PET
commonly used in milk and juice bottles, detergent bottles.
shampoo bottles, grocery bags, and cereal box iners.
2 PE-HD, Polyethylene (high density)
HDPE
can be flexible or
rigid
is used for plumbing pipes, clear food packaging, shrink
wrap, plastic children’s
toys, tablecloths, vinyl
flooring, children’s play mats, and blister packs (such as for medicines).
3 PVC, Polyvinyl chloride
PVC
used for dry cleaning bags, bread
bags, newspaper bags, produce bags, and garbage bags, as well as
“paper” milk cartons and
hot/cold beverage cups.
04 PE-LD, Polyethylene (low density)
LDPE
used to make
yogurt containers, deli
food containers, furniture,
luggage and winter clothing insulation.
05 PP
Polypropylene
also popularly known as Styrofoam, is used for cups, plates, take-out
containers, supermarket meat trays, and packing peanuts.
06 PS
Polystyrene
Any plastic item not made
from the above six
plastics is lumped
together HERE
things like CD’s baby
bottles and headlight
lens
07 O
Bisphenol A and others
formed from a series of reactions, often of _________ type, in which any two
species can react at any time leading
to a larger molecule.
CONDENSATION POLYMERS, condensation
form of a step-growth
polymerization where smaller
molecules or monomers react with
each other to form larger structural
units (usually polymers) while
releasing by-products
CONDENSATION POLYMERS
releasing by-products in CONDENSATION POLYMERS.
water
or methanol molecule
The by-products are normally referred to as
condensate.
✓ This reaction can occur between any two growing polymer molecules
CONDENSATION POLYMERS
✓ This reaction can occur between any two
growing polymer molecules and can be
represented by
(image 33)
Several synthetic condensation polymers
include
nylon
kevlar
polyester
Bakelite,
Melamine
polycarbonates
polyurethanes
epoxies
produced by reactions in which monomers are
added one after another to a rapidly growing chain.
Addition polymers
✓Examples of addition polymers are
polystyrene
polyethylene,
polyacrylonitrile
polymethyl methacrylate
polyvinyl chloride
if n is added in an ethene, it would result in a
polyethene (image 34)
The addition polymerization can be schematically represented as follows
(image 34)
✓Plastics that soften when heated and
become firm again when cooled
THERMOPLASTICS
This is the more popular type of plastic because
the heating and cooling may be repeated
and reformed.
thermoplastic
Most linear polymers and those having
some branched structures with flexible
chains are
thermoplastic
✓Examples of common thermoplastic
polymers include
polyethylene
polystyrene
poly(ethylene terephthalate)
poly(vinyl chloride)
polypropylene,
polycarbonate
nylon
Teflon
These are plastics that soften when heated and can
be molded but harden permanently.
THERMOSETS
They will
decompose when reheated.
THERMOSETS
✓ A thermoset when heated, undergoes a chemical
change to produce a
cross-linked, solid polymer. cross-linked, solid polymer.
Thermosets usually exist initially as liquids called
prepolymers
they can be shaped into desired forms
by the application of heat and pressure but are
incapable of undergoing repeated cycles of softening
and hardening.
prepolymers of thermosets
Principal examples of thermosets include
epoxy
phenolformaldehyde resins
unsaturated polyesters.
✓ Another example of thermosets
Bakelite
used in toasters,
handles for pots and pans, dishes, electrical outlets
and billiard ba
Bakelite
differences (image 37)
- thermoplastic
- thermosets
draw the graph showing differences between thermoplastics and thermoset
(image 37)
a polymer that is irreversibly hardened by heat
thermoset
only the monomer
(and possibly catalyst and initiator, but no
solvent) is fed into the reactor.
▪ BULK POLYMERIZATION
The
monomer undergoes polymerization, at the
end of which a solid mass is removed as
the
polymer product
(image 38)
bulk polymerization
Example of polymers that can be produced
by bulk polymerization are
polyvinyl
chloride (PVC)
polyethylene (PE)
Polypropylene (PP)
Polyethylene
terephthalate (PET)
Polystyrene (PS),
Polyvinylidene chloride (PVDC)
Polytetrafluoroethylene (PTFE).
involves polymerization of a
monomer in a solvent in
which both the monomer
(reactant) and polymer
(product) are soluble.
✓Solution polymerization
Reactant and product in Solution polymerization
monomer
(reactant) and polymer
(product)
usage of ✓Solution polymerization
in the industry
production of
polyacrylonitrile
polyacrylic
acid
polyacrylamide
polyvinyl alcohol
polybutadiene
refers to
polymerization in an aqueous medium with
the monomer as the dispersed phase.
Consequently, the polymer resulting from
such a system forms a solid dispersed phase.
Suspension polymerization
✓Several commercially important ______________ are manufactured using
suspension polymerization
vinyl
copolymers
Example of commercially important vinyl copolymers which are manufactured using
suspension polymerization
polystyrene (general purpose, expandable and
high impact)
polymethyl methacrylate
polyvinyl acetate
styrene–acrylonitrile (SAN)
copolymers
acrylonitrile–butadiene–styrene
(ABS) copolymers
polyvinyl chloride (PVC).
(image 40)
suspension polymerization
similar
to suspension polymerization, but
the initiator is located in the
aqueous phase (continuous phase)
in contrast to the monomer
(dispersed phase) in suspension
polymerization.
EMULSION POLYMERIZATION
in EMULSION POLYMERIZATION, where the initiator is located
aqueous phase (continuous phase)
example of emulsion polymerization is used
for the commercial manufacture of
many important polymers including
polyvinyl chloride (PVC)
polymethyl methacrylate
polystyrene
quantifies how much stress the
material will endure before failing
tensile strength of a material
Tensile strength increases with
polymer chain length
quantifies the
elasticity of the polymer
✓ Young’s Modulus
ratio of the rate of
change of stress to strain.
✓ Young’s Modulus
relate to how rapidly
molecules move through the polymer matrix
▪ TRANSPORT PROPERTIES
example of ▪ TRANSPORT PROPERTIES
diffusivity
important in many applications of polymers for films
and membranes.
▪ TRANSPORT PROPERTIES
a transition from a crystalline or
semi-crystalline phase to a solid amorphous phase
NOT a
solid-liquid phase transition
➢MELTING POINT
a crucial physical
parameter for polymer manufacturing, processing, and use
glass-transition temperature (Tg)
✓ Below Tg
molecular motions are frozen, and polymers are brittle
and glassy.
Above Tg
molecular motions are activated, and
polymers are rubbery and viscous
