Before midterm Flashcards
(313 cards)
1
Q
Substance composed of macromolecules (IUPAC)
A
Polymer
2
Q
Molecule of high relative molecular mass, the structure of which essentially comprises the multiple repetition of units derived
A
Macromolecules
3
Q
Meaning of poly and meros
A
Poly-many
Meros-parts
4
Q
Polymer is made up of repetition of simpler unit called
A
Mer
5
Q
Long chain molecule composed of large number of repeating units of identical structure
A
Polymer
6
Q
Two classifications of polymer
A
- Natural
- Synthetic
7
Q
Natural polymers (biopolymer)
A
- Silk
- Rubber
- Cellulose
- Wool
- Starch
6? Collagen - DNA
8
Q
Prepared in lab by chemical reaction
A
Synthetic polymer
Polystyrene
Polyethylene
Nylon
9
Q
Generally, polymer have molecular weights greater and above ___
A
5000
10
Q
Coined the definition of polymer (poly and meros)
A
Jons Jacob Berzelius
11
Q
Modern def of polymer
A
Hermann Staudinger 1920
12
Q
Homers company of London recorded use of horn and tortoiseshell (natural plastic)
A
1284
13
Q
Ancient Mayan civilization
Children of mayans were found to play with balls from rubber trees
A
1500s
14
Q
Charles Macintosh uses rubber gum for waterproof garments
A
1823
15
Q
Anselme Payen identified cellulose
A
1838
16
Q
Edward Simon discovered polystyrene
A
1839
17
Q
He discovered vulcanization by combining natural rubber with sulfur by heating it to 270F
A
Charles Goodyear
18
Q
Goodyear patents vulcanization
A
1844
19
Q
1846
A
Christian Friedrich Schonbein synthesized nitrocellulose
20
Q
Alexander Parkes patents first thermoplastic (Parkesine)
A
1856
21
Q
John Wesley and Isaiah (Hyatt borthers) produced celluloid
A
1868
22
Q
Eugen Baumann created PVC
A
1872
23
Q
Cross and Bevan created viscous silk (rayon)
A
1892
24
Q
Leo Baekeland producedq phenol-formaldehyde, first synthetic plastic (Bakelite) later known as phenolic resin
A
1907
25
Fritz Klatte patented manufacturing process of PVC
Polyvinyl acetate
1912
26
BF Good rich discovered adhesives
Vinyl age
1926
27
Scotch tape
1930
28
Polyethylene synthesis by Eric
Fawcett and Reginald Gibson
1933
29
Melamine formaldehyde
1933
30
Nylon by Wallace Carothers working at DuPont
1935
31
Father of synthetic polymer science
Wallace Carothers
32
Neoprint
DuPrint
33
Wulff brothers- polystyrene
1936
34
Otto Bayer- polyurethane
1937
35
Roy Plunkett- Teflon
Polytetra fluroethylene
1938
36
PET polyethylene terephthalate John Rex Whinfield and James Tennant Dickson
1941
37
Textiles
1950s
38
First blue HDPE
1980
39
Nanotechnology
2000-2010
40
Discovered at Rice University, can stop 9mm bullet
Bulletproof polymer
41
Uni of Sheffield mimics hemoglobin
Plastics blood
42
Can produce electricity from sunlight
Plastic solar cells
43
Used in neurological applications to help control epilepsy, parkinson's disease
Implantable polymers
44
Space flight lightweight carbon composite material
Commercial
45
Body parts can be printed using plastic materials
3D printed
46
Organic light emitting diodes
Flexible plastic screens
47
Driverless vehicle frkm plastic parts
Driverless cars
48
50000 of bottles for vaccines and hand sanitizer
Covid-19
49
Polymer will continue as long as ___ is available
Pteroleum
50
Importance of polymer engg
1. Select right material and production process for application (material properties, service condition, service life, impact to environment and health and safety, economics, appearance
2. Assess product liability- not endanger the user
3. Devleop and automate oroduction techniques
4. Design for recyclability
5. Solve provlems
6. Challenge and replace traditional materials
51
Space shuttle disaster 1986
Space Shuttle Challenger STS-26
52
Reason of disaster
Selection of O-Ring seals (crystallized during stress)
53
Assess materials
Availability
Properties
Processability
Suitability
Aesthetics and history
Environment impact
54
▪ Each C atom has ___ electrons that participate in covalent bonding, each H atom
has only ___ bonding electron.
4, 1
55
Molecules that have double, and triple covalent bonds are termed
unsaturated
56
all bonds are single ones, and no new atoms may be
joined without the removal of others that are already bonded
saturated hydrocarbon
57
a low-molecular-weight polymer. It contains at least
two monomer units
oligomer
58
oligomer of polyethylene
hexatriacontane
59
repeat units of polyethylene, polyvinyl chloride, polytetrafluoroethylene, polypropylene, and polystyrene
PE- C2H4
PVC-C2H3Cl
PTFE-C2F4
PP-C2H3(CH3)
PS-C2H3(C6H6)
60
specifies the length of the polymer molecule.
degree of polymerization, n
61
a dimensionless quantity given by the sum of the atomic
weights in the molecular formula
Molecular weight
62
relation between degree of polymerization and molecular weight M of
the same macromolecule is given by
M = (DP)Mo
where Mo is the formula weight of repeating unit
63
Classification of Polymers
1. BASED ON
ORIGIN
2. POLYMER
STRUCTURE
3. BASED ON
POLYMERIZATION
MECHANISM
4. ACCORDING TO
THERMAL PROCESSING
BEHAVIOR
5. BASED ON
PREPARATIVE
TECHNIQUE
64
Classify according to recycle number
PET, PvC, LDPE, PP, HDPE, PS, other
1. PET- water bottles
2. HDPE- shampoo bottles
3. PVC- cleaning products
4. LDPE-bread bags
5. PP- yogurt cups
6. PS- take away and hard packaging toys
7 other- baby bottles, cds
65
molecule is simply its interlinking capacity, or
the number of sites it has available for bonding with other
molecules under the specific polymerization conditions
functionality
66
those in which the
repeat units are joined together end to
end in single chains. These long chains
are flexible and may be thought of as a
mass of “spaghetti.
Linear polymers
67
examples of linear polymers
PE, PVC, PS, Polyamides
68
have side chains or branches
growing out from the main chain. The side chains or
branches are made of the same repeating units as the
main polymer chains.
Branched polymers
69
example of branched polymer
LDPE
70
adjacent linear
chains are joined one to another at
various positions by covalent bonds
crosslinked polymers
71
example of crosslinks
bakelite, melamine
72
Multifunctional monomers forming
three or more active covalent bonds
make three dimensional networks
network polymers
73
the material
exhibits organized and tightly packed molecular
chains
crystalline polymer
74
examples of crystalline polymers
PE, PET, PETF
75
polymers that have no
crystalline regions and no uniformly packed
molecules
Amorphous polymers
76
example of amorphous polymers
Natural rubber latex and styrene-butadiene rubber
77
a measure of the degree of order or
orientation in a crystal
degree of crystallinity
78
When all of the repeating units along a chain are of
the same type, the resulting polymer is called a
homopolymer
79
to produce a
polymer that has increased mechanical properties.
These enhanced mechanical properties include:
tensile strength, stiffness, impact resistance, and
short-term creep resistance
homopolymers
80
polymer made up of more
than one type of monomer unit
copolymer
81
Copolymers are produced by polymerizing
two or more types of monomer together in
a process referred to as
copolymerization
82
Copolymers produced through copolymerization are
sometimes also referred to as
biopolymers
83
Copolymer structures
1. random ABBABABBAABBBA
2. alternating ABABABABA
3. block (with one or more long
uninterrupted sequences of each mer in the chain) AAAAAAAAAABBBBBBBBB
4 graft- a branched
copolymer with a backbone of one type of mer and
one or more side chains of another me
84
linear polymers with high
symmetry and high intermolecular forces that
result usually from the presence of polar
groups
Fibers
85
are molecules with
irregular structure, weak
intermolecular attractive forces, and
very flexible polymer chains
Elastomers
86
a polymer, typically
modified with
additives, which can
be molded or
shaped under
reasonable
conditions of
pressure and
temperature
plastic material
87
are formed
from a series of reactions, often of
condensation type, in which any two
species can react at any time leading
to a larger molecule
Condensation polymers
88
smaller
molecules or monomers react with
each other to form larger structural
units (usually polymers) while
releasing by-products such as water
or methanol molecule. The byproducts are normally referred to as
condensate
step-growth
polymerization
89
are produced by reactions in which monomers are
added one after another to a rapidly growing chain
Addition polymers
90
Plastics that soften when heated and
become firm again when cooled
THERMOPLASTICS
91
plastics that soften when heated and can
be molded but harden permanently. They will
decompose when reheated.
THERMOSETS
92
only the monomer
(and possibly catalyst and initiator, but no
solvent) is fed into the reactor
bulk polymerization
93
involves polymerization of a
monomer in a solvent in
which both the monomer
(reactant) and polymer
(product) are soluble
Solution polymerization
94
refers to
polymerization in an aqueous medium with
the monomer as the dispersed phase
Suspension polymerization
95
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
96
quantifies how much stress the
material will endure before failing
tensile strength
97
quantifies the
elasticity of the polymer; It is defined as the ratio of rate of
change of stress to strain.
Young's Modulus
98
relate to how rapidly
molecules move through the polymer matrix
Transport properties
99
suggests not a
solid-liquid phase transition but a transition from a crystalline or
semi-crystalline phase to a solid amorphous phase
melting point
100
______ Tg, molecular motions are frozen, and polymers are brittle
and glassy
below
101
____ Tg, molecular motions are activated, and
polymers are rubbery and viscous
above
102
analytical branch of polymer science; a technique used to determine the
molecular properties, structure, and behavior of polymers
Polymer characterization
103
involves a count of the number
of molecules of each species
number-average molecular weight, Mn
104
number-average molecular weight, Mn
polydispersity index (PDI)
105
chemical method use for calculating the numberaverage molecular weight of polymer samples whose molecules contain
reactive functional groups at one end or both ends of the molecule (for mw of less than 20000)
end-group analysis
106
not applicable to
polymers that lack reactive or easily
detectable end-groups.
End-group
Analysis
107
Properties of solutions that depend on the number of molecules present
and not on the kind of molecules
colligative properties
108
In applying this method, the boiling point of a
solution of known concentration is compared
to that of the solvent at the same pressure
Ebulliometry (Boiling Point Elevation)
109
Calculation of the freezing-point depression of the
solvent and hence the molecular weight of the solute
by this method proceeds exactly the same way as for
the boiling-point elevation (up to mw of 50000)
Cryoscopy (Freezing Point Depression)
110
a technique for the
determination of molecular masses of polymers
by means of osmosis. The phenomenon of
osmosis describes the attempt of solvent
molecules to go through a semipermeable
membrane into a solution (20k-30 k mw and less than 500k)
Membrane osmometry
111
depends
on the light, when the light is passing through polymer solution, it is
measured by lose energy because of absorption, conversion to heat and
scattering. The intensity of scattered light relies on the concentration, size
and polarizability that is proportionality constant which depends on the
molecular weight.
Light-Scattering Method
112
a technique that measures the
intensity of the scattered light to obtain the average
molecular weight Mw of a macromolecule like a polymer or a
protein in solution.
Static light scattering
113
it provides
information about macromolecules without any calibration with polymer
standards
it is non-selective and thus requires
purified extracts without co-eluting contaminants in order to generate
useful data
Light-Scattering Method
114
is defined as the measure of the opposing force of material to
flow
Viscosity
115
gives the relationship between viscosity and
average molecular weight
Mark-Houwink equation
116
most common type of
viscometer that is used for the
determination of viscosity of polymer
solution.
Ubbelohde
viscometer
117
an
extremely powerful method for determining the
complete molecular weight distribution and
average molecular weights
Gel permeation chromatography (GPC)
118
are used to purify and characterize
low-molecular-weight polymers
Ultracentrifuges
119
proved to be a rapid and precise method of molecular-weight
determination, often requiring as little as a half hour per sample.
GPC
120
a microscale property that is
largely dictated by the amorphous or crystalline portions
of the polymer chains and their influence on each other
Polymer morphology
121
the
polymer is allowed to react to form low molecular-weight fragments that are
condensed at liquid-air temperature
Mass
Spectrometry
122
an ionization
technique that uses a laser energy-absorbing matrix to
create ions from large molecules with minimal
fragmentation
matrix-assisted laser
desorption/ionization (MALDI)
123
Provides accurate identification of
compounds based on their mass spectra, allowing the detection of
unknown or trace compounds.
Offers high sensitivity, enabling the
detection of compounds at very low concentrations, and high specificity
due to the unique mass spectra of different compounds
Allows accurate quantification of compounds
based on ion abundance
Mass Spectrometry
124
a method of separation in
which gaseous or vaporized components are
distributed between a moving gas phase and fixed
liquid phase or solid adsorbent.
Gas Chromatography
125
an analytical method that combines the features
of gas-chromatography and mass spectrometry to
identify different substances within a test sample
Gas chromatography–mass spectrometry (GC–MS)
126
High Separation Efficiency
Quantitative Analysis
Wide Range of Applications
Gas Chromatography
127
the analysis
of infrared light interacting with a
molecule. This can be analyzed in
three ways by measuring absorption,
emission and reflection.
Infrared Spectroscopy
128
measures the
vibrations of atoms, and based on
this it is possible to determine the
functional groups.
IR Spectroscopy
129
is a non-destructive analytical technique that
measures the absorption or transmission of
infrared radiation by a sample as a function of
frequency or wavelength
Fourier transform infrared spectroscopy (FTIR)
130
is a
powerful analytical technique used to study the molecular
structure, dynamics, and composition of organic and inorganic
compounds
Nuclear Magnetic Resonance (NMR) spectroscopy
131
exploits the magnetic properties of certain atomic nuclei
within a magnetic field to provide detailed information about
the chemical environment of atoms in a molecule
Nuclear Magnetic Resonance (NMR) spectroscopy
132
works by measuring the presence of paramagnetic ions or molecules with unpaired electrons,
and by observing the resonant absorption of microwaves within a static magnetic field.
Electron Paramagnetic
Resonance Spectroscopy
133
is a valuable technique for analyzing
polymers, providing insights into their electronic structure,
composition, and molecular interactions.
is used to study the
absorption of ultraviolet and visible light by polymer
molecules.
Ultraviolet–visible
spectroscopy
134
Provides information about the
presence of specific functional groups or chromophores
within polymers.
Ultraviolet–
visible
spectroscopy
135
a powerful qualitative and
quantitative tool with some particular advantages for the
analysis of polymers
Raman spectroscopy
136
an analytical technique used to
study molecular vibrations in materials by measuring the
scattering of light when it interacts with a sample
Raman spectroscopy
137
a laser beam is directed onto a
sample, and a small fraction of the incident light
undergoes inelastic scattering. The scattered light
exhibits energy shifts corresponding to the vibrational
energy levels of the molecules in the sample.
Raman Spectroscopy
138
a nondestructive
technique that provides detailed information about the
crystallographic structure, chemical composition, and
physical properties of a material.
works by passing X-rays through a sample and analyzing
the diffraction pattern produced by the scattering of X-rays
by the polymer molecules.
X-ray diffraction (XRD)
139
is a
category of microscopes
that uses visible light to
magnify and image small
samples.
light microscope
140
a technique used to observe the
orientation of molecules in a sample under a microscope. It is
often used with polymers to study their structure, as the
orientation of the polymer chains can reveal information about
their molecular organization
Polarized-light
Microscopy
141
is a type of
microscopy that uses interference patterns
produced by the incoherent light scattered by
specimens to create an image
Phase-contrast microscopy
142
powerful tool in the
study of the morphology of crystalline polymer
Electron Microscopy
143
uses a beam of
electrons and their wave-like characteristics to
magnify an object's image, unlike the optical
microscope that uses visible light to magnify
images
electron microscope
144
is a
type of electron microscope that produces
images of a sample by scanning the surface
with a focused beam of electrons. The
electrons interact with atoms in the sample,
producing various signals that contain
information about the surface topography
and composition of the sample
scanning electron microscope (SEM)
145
) is a
type of electron microscope that transmits
electrons through a thin sample, resulting in an
image of the sample's interior structure at the
atomic level
transmission electron microscope (TEM)
146
is a
thermoanalytical technique in which the difference in
the amount of heat required to increase the
temperature of a sample and reference is measured
as a function of temperature
Differential scanning calorimetry (DSC)
147
the material under study and an inert reference
are made to undergo identical thermal cycles, (i.e.,
same cooling or heating programme) while recording
any temperature difference between sample and
reference.
Differential
Thermal Analysis
148
a sensitive balance is used to follow the
weight change of the sample as a function of
temperature
Thermogravimetric
Analysis
149
measures the mechanical
response of a polymer system
as the temperature is changed
Thermomechanical
Analysis
150
This is
usually done by measuring
continuously the force
developed as the sample is
elongated at constant rate of
extension.
Stress-Strain
Properties in
Tension
151
is the maximum
stress that a material can withstand
while being stretched or pulled
before breaking.
Tensile strength
152
material property
and is the stress corresponding to
the yield point at which the material
begins to deform plastically.
Yield strength
153
is a mechanical property of solid
materials that measures the tensile
or compressive stiffness when the
force is applied lengthwise
Young's modulus (or Young modulus)
154
a measure of the stress or force that is applied in a direction parallel to the surface
of a material. It is typically defined as the force per unit area perpendicular to the plane of shearing
force
Shear stress
155
refers to the bending or storage of stress or strain in a material. It is a mechanical
phenomenon that occurs when force is applied to a flexible material. The amount of bending that
occurs depends on the material's properties, such as its modulus of elasticity and cross-sectional
area.
Flexure
156
the force that is responsible for the deformation of the material such that the
volume of the material reduces. It is the stress experienced by a material which leads to a smaller
volume. High compressive stress leads to failure of the material due to tension
Compressive stress
157
twisting of an object due to an applied torque.
Torsion
158
When subjected to cyclic mechanical
stresses, most materials fail at a stress
considerably lower than that required to
cause rupture in a single stress cycle
fatigue
159
performed to measure the
reduction in stiffness and strength of
materials under repeated loading and to
determine the total number of load cycles to
failure
Fatigue tests
160
measure the ability of a
material to resist deformation in response
to a sudden load
Impact tests
161
Four commonly used types of impact tests
Charpy, Izod, drop-weight, and
dynamic tear tests
162
occurs if the material behaves elastically up to the point of failure.
Brittle rupture
163
occurs when the specimen is permanently distorted near the
point of failure.
Ductile rupture
164
temperature at the onset of brittleness, is usually
determined by subjecting a specimen to impact in a standardized but empirical
way.
brittle point
165
commonly measured by tests in which a
pendulum with a massive striking edge is allowed to hit the specimen.
Impact strength
166
In one test of tear strength, a
specimen is torn apart at a cut made
by a sharp blade
Tear
Resistance
167
composite property
combining concepts of resistance to
penetration, scratching, marring, and
so on
Hardness
168
takes the form of a scratch test, in which
the material is subjected to many
scratches, usually from contact with an
abrasive wheel or a stream of falling
abrasive material
Abrasion
Resistance
169
defined as the
temperature at which the resin flows under a
given load on heating.
softening temperature
170
usually tested
as the burning rate of a specified
sample. The self-extinguishing
tendency of the material on the
removal of an external flame is
also important.
flammability
171
ratio of the intensities of light passing through and light
incident on the specimen (transparent)
transmittance
172
ratio of the intensities of the reflected and the incident light (opaque)
opaque
173
one that transmit part and reflects part of the
light incident on it
translucent
174
subjective sensation in
the brain resulting from the
perception of those aspects of the
appearance of objects that result
from the spectral composition of the
light reaching the eye
Color
175
description of color
requires specification of three
variables
hue, lightness, and
saturation
176
geometrically selective
reflectance of a surface responsible
for its shiny or lustrous appearance
Gloss
177
percentage of transmitted
light that in passing through the
specimen deviates from the
incident beam by forward (2.5deg)
haze
178
defined as the state permitting perception of objects through or
beyond the specimen
Transparency
179
efers to the ability of a polymer material to resist the flow of
electrical current
Resistivity
180
measure of a
material's ability to store electric charge
dielectric constant
181
a
measure of its ability to sustain high-voltage
differences without current breakdown
dielectric strength
182
the ability of the plastic material to resist
the action of a high voltage electrical arc and resist the
formation of a conducting path along its surface under a
given time
Arc resistance
183
the specimen fails by breaking when exposed to
mechanical stress in the presence of an organic liquid of an aqueous
solution of a soap or other wetting agent
environmental stress
cracking
184
specimen fails by the development of a multitude of very small cracks
in the presence of an organic liquid or its vapor, with or without the
presence of mechanical stress
crazing
185
the product of the solubility of the gas or vapor
in the polymer and its diffusion coefficient; ability of a polymer material to allow certain gases or vapors to
pass through it
Vapor Permeability
186
directly measured as the rate of transfer of vapor through unit thickness of the
polymer in film form, per unit area and pressure difference across the film
Permeability
187
refers to the process of
degradation of polymers, or large molecules, due to
exposure to external factors such as sunlight,
temperature, and chemicals
Weathering of polymers
188
suggested a
classification of polymers into two
groups: condensation (step-growth)
and addition (chain-growth) polymers
W. H. Carothers (1929)
189
a process by which monomer
units are attached one at a time in chainlike
fashion to form a linear molecule
Chain-growth polymerization or addition
polymerization
190
chain reaction in which the
growth of a polymer chain proceeds exclusively by
reaction(s) between monomer(s) and reactive
site(s) on the polymer chain with regeneration of
the reactive site(s) at the end of each growth step
Chain-growth polymerization or addition
polymerization
191
The most common
unsaturated compounds that undergo chain-growth polymerization
olefins
192
polymerization
technique where unsaturated monomer molecules
add onto the active site on a growing polymer chain
one at a time
Chain-growth polymerization
193
three fundamental steps of CHAIN-GROWTH
POLYMERIZATION
initiation,
propagation, and termination
194
A chain
polymerization in which the
kinetic
-chain carriers are
radicals
Free Radical
Polymerization
195
method of
polymerization by which a
polymer forms by the successive
addition of free
-radical building
blocks (repeat units)
Free
-radical polymerization
196
involves the acquisition of an
active site by the monomer
Initiation
197
initiation of free-radical
polymerization is brought about by the
addition of small quantities of
compounds called
initiators
198
usually a weak organic compound
that can be decomposed thermally or by
irradiation to produce free radicals, which are
molecules containing atoms with unpaired
electrons
initiator
199
two steps of initiation in free radical polymerization
dissociation of the initiator to form two radical species, followed by
addition of a single monomer molecule to the initiating radical (the
association step
200
involves the dissociation of a radical initiator molecule (I) which is
easily dissociated by heat or light into two free radicals
Chain initiation
201
involves the linear
growth of the polymer chain by
the sequential addition of
monomer units to this active
growing chain molecule
Propagation
202
a reaction of an active center on the
growing polymer molecule, which
adds one monomer molecule to
form a new polymer molecule
(RM1
°) one repeat unit longer
chain propagation
203
involves the reaction of any two free radicals
with each other, either by combination or disproportionation
termination
204
Two propagating chains are terminated when two radicals combine
to form an electron-pair (covalent) bond as in the reaction above
termination by combination (or coupling)
205
reaction of the
unpaired electrons of two chains to
form a covalent bond between them
Combination
206
This termination step involves two growing molecules that react to from
two “dead chains”
disproportionation
207
transfer of a
hydrogen atom from one chain to the
other, so that the two product chain
molecules are unchanged in length but
are no longer free radicals
Disproportionation
208
a growing polymer chain is deactivated or terminated
by transferring its growth activity to a previously inactive species
chain transfer
209
involve chain carriers or reactive centers that
are organic ions or charged organic groups
Ionic polymerizations
210
type of chain growth
polymerization in which a cationic initiator transfers
charge to a monomer, which then becomes reactive
Cationic polymerization
211
The initiation of the polymerization is accomplished by
catalysts that are ____ donors
proton
212
To be effective, these
catalysts in cationic polymerization generally require the presence of a Lewis base
such as water, alcohol, or acetic acid as a
cocatalyst
213
occurs either by rearrangement of the ion pair to yield a polymer
molecule with an unsaturated terminal unit and the original complex or through
transfer to a monomer
Termination
214
a form of chain-growth polymerization or addition
polymerization that involves the
polymerization of monomers initiated with
anions
Anionic polymerization
215
The initiator in an anionic polymerization may be any strong
_____
nucleophile
216
commonly used initiator systems
for anionic polymerization
1. alkali metals
2. organometallic compounds
3. lewis bases
4. high-energy radiation
217
anionic polymerization is
sometimes called “_____” polymerization
living
218
In polymerizations of this type, each monomer is inserted
between the growing macromolecule and the initiator
Coordination Polymerization
219
most important group of initiators in Coordination Polymerization
Ziegler-Natta catalysts
220
pioneers on the field of coordination polymerization in the 1950s
Karl Ziegler in
Germany and Giulio Natta in Italy
221
Ziegler–Natta catalyst systems consist of a mixture of
the following two classes of compounds
1. Compounds (normally halides) of transition
elements of groups IV to VIII
2. Compounds (hydrides, alkyls, or aryls) of elements
of groups I to IV, called cocatalysts
222
arises because of order in the
spatial structures of polymer chains
Stereoregularity
223
Coordination
Polymerization -
Mechanism (tactics)
1. isotactic (HHHH)
2. syndiotactic (HHHRHHHRHHHR)
3. atactic (HHHRHHHHHR)
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refers
to a type of polymerization mechanism in
which bi-functional or multifunctional
monomers react to form first dimers, then
trimers, longer oligomers and eventually
long chain polymers
Step-growth polymerization
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simply its interlinking capacity, or the
number of sites it has available for
bonding with other molecules under the
specific polymerization conditions
functionality
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molecular weight of the polymer chain builds
up slowly and there is only one reaction mechanism for the formation of polymer
step-growth polymerization
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Small molecule is eliminated at each step
Polycondensation
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Monomers react without the elimination of a small molecule
Polyaddition
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the largest volume
synthetic fiber
poly(ethylene terephthalate)
(PETP)
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special class of polyesters derived from carbonic acid
Polycarbonates
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are characterized by the
presence of amide linkages (–CONH–) on the polymer main chain
Polyamides, or nylons
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condensation
polymers obtained from the reaction
of dianhydrides with diamines
Polyimides
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synthetic heterocycles with a wide
range of applications due to their physical and
chemical properties. These man-made
molecules are commonly used in medicinal,
agricultural, and environmental areas due to
their ability to form strong metallic complexes
and their unique thermal and electrical
properties.
Polybenzimidazoles and polybenzoxazoles
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a type of polymer
that consists of repeating units connected by aromatic
linkers, such as benzene rings
Aromatic ladder polymers
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employed in the production of aminoplasts and phenoplasts,
which are two different but related classes of thermoset polymers
Formaldehyde
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e products of the condensation reaction between either urea (urea–
formaldehyde or UF resins) or melamine (melamine–formaldehyde or MF resins)
with formaldehyde
Aminoplasts
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prepared from
the condensation products of phenol or resorcinol and formaldehyde
Phenoplasts or phenolic (phenol–formaldehyde or PF)
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polymers consisting of
monomers joined together by ether linkages
(two carbon atoms bonded to an oxygen
atom).
Polyethers
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s used as electrical insulators and structural parts in the building of
engines and vehicles
poly(phenylene sulfide)
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may be synthesized by
the nucleophilic substitution of alkali
salts of biphenates with activated
aromatic dihalides
Polysulfones
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A polymerization in which a cyclic monomer yields
a monomeric unit which is acyclic or contains fewer cycles than the
monomer
RING-OPENING POLYMERIZATION
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a form of chain-growth
polymerization in which the terminus of a polymer chain attacks
cyclic monomers to form a longer polymer. The reactive center can
be radical, anionic or cationic
Ring-opening polymerization (ROP)
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As temperature _____, the molecules of
the polymer move faster and their kinetic
energy increases. This can cause the
polymer to expand, and its shape to change
increases
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Solid polymers that tend to form
ordered regions
crystalline polymers
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Polymers that have no crystals at
al
amorphous.
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In the amorphous region of the polymer,
at lower temperature, the molecules of
the polymer are in frozen state, where the
molecules can vibrate slightly but are not
able to move significantly
glassy state
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When the polymer is heated, the polymer
chains are able to wiggle around each
other, and the polymer becomes soft and
flexible similar to rubber
rubbery state
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The temperature at which the glassy
state makes a transition to rubbery state
glass transition temperature
Tg
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temperature where There is a diffuse transition zone between
the rubbery and liquid states for
crystalline polymers
flow
temperature, Tf
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_____ intermolecular forces cause higher
Tg
strong
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The presence of the ______ (such
as amide, sulfone, carbonyl, p-phenylene
etc.) in the polymer chain reduces the
flexibility of the chain, leading to higher glass
transition temperature
stiffening groups
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restrict
rotational motion and raise the glass transition
temperature
cross-links between chains
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can
restrict rotational freedom, leading to higher
glass transition temperature
Bulky pendant groups
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limits the packing of the chains and hence
increases the rotational motion, tending to less Tg value
Flexible pendant groups
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low molecular weight
and non-volatile materials added to
polymers to increase their chain
flexibility
Plasticizers
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Tg is _______ with
the molecular weight
increased
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The modulus of a polymer ______ with
increasing temperature
decreases
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defined
as the pressure exerted by a fluid
at equilibrium at any point of time
due to the force of gravity
Hydrostatic pressure
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the unit of measurement of an
object's or substance's resistance to being
deformed elastically (i.e., non-permanently)
when a stress is applied to it.
elastic modulus
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s the force causing the
deformation divided by the area to which the
force is applied
stress
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e ratio of the
change in some parameter caused by the deformation to the original value of the
parameter
strain
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describes tensile and compressive
elasticity, or the tendency of an object to deform along an axis
when opposing forces are applied along that axis
Young's modulus (E)
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describes an
object's tendency to shear (the deformation of shape at
constant volume) when acted upon by opposing forces
shear modulus or modulus of rigidity (G)
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describes volumetric elasticity, or the
tendency of an object to deform in all directions when
uniformly loaded in all directions
bulk modulus (K)
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describes the object's tendency to flex
when acted upon by a moment
Flexural modulus (Eflex)
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a material property and
is the stress corresponding to the yield point at which the
material begins to deform plastically
yield strength or yield stress
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the appearance of a crack or complete
separation of an object or material into two or more pieces
under the action of stress
Fracture
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If a displacement develops perpendicular to the surface in fracture, it is
called
normal tensile crack or simply a crack
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the stress at
which a specimen fails
via fracture. This is
usually determined for a
given specimen by a
tensile test, which charts
the stress
–strain curve
Fracture strength, breaking
strength
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a substance that accelerates
chemical reactions without being consumed in
the process
catalyst
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-quantity that measures
the extent to which the reaction has proceeded
-refers to
the degree of crosslinking or bonding between
the monomers in a polymer chain
-defined as the fraction of
functional groups/monomers that have reacted at time t
Extent of reaction
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relating
average functionality (f), extent of reaction (p), and average
degree of polymerization 𝑋ത
𝑛 for polycondensation reaction
carried out for a period
Carother’s Equation
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defined as equal to
the total number of bifunctional initially added, No
, divided by
the remaining number of molecules N after time t
Average degree of polymerization 𝑿n bar
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defined as the
average number of structural units per polymer molecule
average degree of polymerization Xn patience
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Modulus of polymers ___ with high temp, ___ Tg
Decreases
Low
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Pressure exerted by a fluid at equilibrium on a solid surface due to gravity
Hydrostatic pressure
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Effect of pressure on the mech prop of polymers
Elastic Modulus
Yield strength/yield stress
Fracture properties
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A stiffer matl have a ___ elastic modulus
Higher
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Ratio of stress over strain
Elastic modulus
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Types of elastic modulus
Young's
Shear
Bulk
Flexural
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Tensile stress: tensile strain
Young's modulus
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Aka as elastic modulus
Youngs modulus of elasticity
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Describes tensile and compressive elasticity
Youngs modulus
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Tendency of an obj to deform when opposing forces are applied to the axis
Young's modulus
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Shear stress: shear strain
Shear modulus
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Shear modulus aka
Modulus of rigidity (G)
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Objects tendency to shear when opposing forces are applied
Shear modulus
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Describes volumetric elasticity
Bulk modulus
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Tendency of an obj to deform in all directions
Bulk modulus
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Volumetric stress: volumetric strain
Bulk modulus
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Tendency of an object to flex when acted upon by a moment
Flexural modulus (Eflex)
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High hydrostatic pressure, ___ Tg
High
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High elastic modulus, ___ hydrostatic pressure in ___
high
Tension, compression, shear
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Determine the max allowable load
Yield stress/strength
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Yield strength or
Yield stress
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The ___ the yield stress, the __ the hydrostatic pressure
Higher
Higher
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Appearance of crack or complete separation of an obj intk two or more
Fracture
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Displacement perpendiculsr to the surface
Normal tensile crack
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Displacement tangentially
Shear crack, slip band, dislocation
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Shear crack or
slip band, dislocation
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Stress at which specimen fails via fracture
Fracture strength/breaking strength
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Fracture strength is prop to
Yield strength
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Fracture strength or
breaking strength
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Maximum stress
Ultimate tensile strength
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___ ultimate tensile strength, high hydrostatic pressure
High
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Tensile strength: ___ in ductile polymers, ___ in brittle polymers
High, low
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Common catalysts
Acids, bases, enzymes, metal ions
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Important for understanding the ctrl of the growth of poly thru polycondensation reaxns
Carother's eqn
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Fraction of func grps/monomers that have reacted at time t
Extent of reax
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Formation of infinitely large polymer network
Gelation
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2 parts of gelation
Gel
Sol
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In gelation, ___ is soluble in all non degrading solvents
Gel
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In gelation, ___ remains soluble and can be extracted form gel
Sol
