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Polymer engg > Before midterm > Flashcards

Before midterm Flashcards

1
Q

Substance composed of macromolecules (IUPAC)

A

Polymer

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2
Q

Molecule of high relative molecular mass, the structure of which essentially comprises the multiple repetition of units derived

A

Macromolecules

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3
Q

Meaning of poly and meros

A

Poly-many
Meros-parts

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4
Q

Polymer is made up of repetition of simpler unit called

A

Mer

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5
Q

Long chain molecule composed of large number of repeating units of identical structure

A

Polymer

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6
Q

Two classifications of polymer

A
  1. Natural
  2. Synthetic
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7
Q

Natural polymers (biopolymer)

A
  1. Silk
  2. Rubber
  3. Cellulose
  4. Wool
  5. Starch
    6? Collagen
  6. DNA
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8
Q

Prepared in lab by chemical reaction

A

Synthetic polymer
Polystyrene
Polyethylene
Nylon

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9
Q

Generally, polymer have molecular weights greater and above ___

A

5000

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10
Q

Coined the definition of polymer (poly and meros)

A

Jons Jacob Berzelius

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11
Q

Modern def of polymer

A

Hermann Staudinger 1920

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12
Q

Homers company of London recorded use of horn and tortoiseshell (natural plastic)

A

1284

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13
Q

Ancient Mayan civilization
Children of mayans were found to play with balls from rubber trees

A

1500s

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14
Q

Charles Macintosh uses rubber gum for waterproof garments

A

1823

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15
Q

Anselme Payen identified cellulose

A

1838

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16
Q

Edward Simon discovered polystyrene

A

1839

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17
Q

He discovered vulcanization by combining natural rubber with sulfur by heating it to 270F

A

Charles Goodyear

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18
Q

Goodyear patents vulcanization

A

1844

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19
Q

1846

A

Christian Friedrich Schonbein synthesized nitrocellulose

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20
Q

Alexander Parkes patents first thermoplastic (Parkesine)

A

1856

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21
Q

John Wesley and Isaiah (Hyatt borthers) produced celluloid

A

1868

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22
Q

Eugen Baumann created PVC

A

1872

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23
Q

Cross and Bevan created viscous silk (rayon)

A

1892

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24
Q

Leo Baekeland producedq phenol-formaldehyde, first synthetic plastic (Bakelite) later known as phenolic resin

A

1907

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25
Q

Fritz Klatte patented manufacturing process of PVC
Polyvinyl acetate

A

1912

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26
Q

BF Good rich discovered adhesives
Vinyl age

A

1926

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27
Q

Scotch tape

A

1930

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28
Q

Polyethylene synthesis by Eric
Fawcett and Reginald Gibson

A

1933

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29
Q

Melamine formaldehyde

A

1933

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30
Q

Nylon by Wallace Carothers working at DuPont

A

1935

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31
Q

Father of synthetic polymer science

A

Wallace Carothers

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32
Q

Neoprint

A

DuPrint

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33
Q

Wulff brothers- polystyrene

A

1936

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34
Q

Otto Bayer- polyurethane

A

1937

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35
Q

Roy Plunkett- Teflon
Polytetra fluroethylene

A

1938

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36
Q

PET polyethylene terephthalate John Rex Whinfield and James Tennant Dickson

A

1941

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37
Q

Textiles

A

1950s

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38
Q

First blue HDPE

A

1980

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39
Q

Nanotechnology

A

2000-2010

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40
Q

Discovered at Rice University, can stop 9mm bullet

A

Bulletproof polymer

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41
Q

Uni of Sheffield mimics hemoglobin

A

Plastics blood

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42
Q

Can produce electricity from sunlight

A

Plastic solar cells

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43
Q

Used in neurological applications to help control epilepsy, parkinson’s disease

A

Implantable polymers

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44
Q

Space flight lightweight carbon composite material

A

Commercial

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45
Q

Body parts can be printed using plastic materials

A

3D printed

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46
Q

Organic light emitting diodes

A

Flexible plastic screens

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47
Q

Driverless vehicle frkm plastic parts

A

Driverless cars

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48
Q

50000 of bottles for vaccines and hand sanitizer

A

Covid-19

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49
Q

Polymer will continue as long as ___ is available

A

Pteroleum

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50
Q

Importance of polymer engg

A
  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
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51
Q

Space shuttle disaster 1986

A

Space Shuttle Challenger STS-26

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52
Q

Reason of disaster

A

Selection of O-Ring seals (crystallized during stress)

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53
Q

Assess materials

A

Availability
Properties
Processability
Suitability
Aesthetics and history
Environment impact

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54
Q

▪ Each C atom has ___ electrons that participate in covalent bonding, each H atom
has only ___ bonding electron.

A

4, 1

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55
Q

Molecules that have double, and triple covalent bonds are termed

A

unsaturated

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56
Q

all bonds are single ones, and no new atoms may be
joined without the removal of others that are already bonded

A

saturated hydrocarbon

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57
Q

a low-molecular-weight polymer. It contains at least
two monomer units

A

oligomer

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58
Q

oligomer of polyethylene

A

hexatriacontane

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59
Q

repeat units of polyethylene, polyvinyl chloride, polytetrafluoroethylene, polypropylene, and polystyrene

A

PE- C2H4
PVC-C2H3Cl
PTFE-C2F4
PP-C2H3(CH3)
PS-C2H3(C6H6)

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60
Q

specifies the length of the polymer molecule.

A

degree of polymerization, n

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61
Q

a dimensionless quantity given by the sum of the atomic
weights in the molecular formula

A

Molecular weight

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62
Q

relation between degree of polymerization and molecular weight M of
the same macromolecule is given by

A

M = (DP)Mo

where Mo is the formula weight of repeating unit

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63
Q

Classification of Polymers

A
  1. BASED ON
    ORIGIN
  2. POLYMER
    STRUCTURE
  3. BASED ON
    POLYMERIZATION
    MECHANISM
  4. ACCORDING TO
    THERMAL PROCESSING
    BEHAVIOR
  5. BASED ON
    PREPARATIVE
    TECHNIQUE
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64
Q

Classify according to recycle number
PET, PvC, LDPE, PP, HDPE, PS, other

A
  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
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65
Q

molecule is simply its interlinking capacity, or
the number of sites it has available for bonding with other
molecules under the specific polymerization conditions

A

functionality

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66
Q

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.

A

Linear polymers

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67
Q

examples of linear polymers

A

PE, PVC, PS, Polyamides

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68
Q

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.

A

Branched polymers

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69
Q

example of branched polymer

A

LDPE

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70
Q

adjacent linear
chains are joined one to another at
various positions by covalent bonds

A

crosslinked polymers

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71
Q

example of crosslinks

A

bakelite, melamine

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72
Q

Multifunctional monomers forming
three or more active covalent bonds
make three dimensional networks

A

network polymers

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73
Q

the material
exhibits organized and tightly packed molecular
chains

A

crystalline polymer

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74
Q

examples of crystalline polymers

A

PE, PET, PETF

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75
Q

polymers that have no
crystalline regions and no uniformly packed
molecules

A

Amorphous polymers

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76
Q

example of amorphous polymers

A

Natural rubber latex and styrene-butadiene rubber

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77
Q

a measure of the degree of order or
orientation in a crystal

A

degree of crystallinity

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78
Q

When all of the repeating units along a chain are of
the same type, the resulting polymer is called a

A

homopolymer

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79
Q

to produce a
polymer that has increased mechanical properties.
These enhanced mechanical properties include:
tensile strength, stiffness, impact resistance, and
short-term creep resistance

A

homopolymers

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80
Q

polymer made up of more
than one type of monomer unit

A

copolymer

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81
Q

Copolymers are produced by polymerizing
two or more types of monomer together in
a process referred to as

A

copolymerization

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82
Q

Copolymers produced through copolymerization are
sometimes also referred to as

A

biopolymers

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83
Q

Copolymer structures

A
  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
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84
Q

linear polymers with high
symmetry and high intermolecular forces that
result usually from the presence of polar
groups

A

Fibers

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85
Q

are molecules with
irregular structure, weak
intermolecular attractive forces, and
very flexible polymer chains

A

Elastomers

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86
Q

a polymer, typically
modified with
additives, which can
be molded or
shaped under
reasonable
conditions of
pressure and
temperature

A

plastic material

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87
Q

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

A

Condensation polymers

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88
Q

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

A

step-growth
polymerization

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89
Q

are produced by reactions in which monomers are
added one after another to a rapidly growing chain

A

Addition polymers

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90
Q

Plastics that soften when heated and
become firm again when cooled

A

THERMOPLASTICS

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91
Q

plastics that soften when heated and can
be molded but harden permanently. They will
decompose when reheated.

A

THERMOSETS

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92
Q

only the monomer
(and possibly catalyst and initiator, but no
solvent) is fed into the reactor

A

bulk polymerization

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93
Q

involves polymerization of a
monomer in a solvent in
which both the monomer
(reactant) and polymer
(product) are soluble

A

Solution polymerization

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94
Q

refers to
polymerization in an aqueous medium with
the monomer as the dispersed phase

A

Suspension polymerization

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95
Q

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

A

Emulsion polymerization

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96
Q

quantifies how much stress the
material will endure before failing

A

tensile strength

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97
Q

quantifies the
elasticity of the polymer; It is defined as the ratio of rate of
change of stress to strain.

A

Young’s Modulus

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98
Q

relate to how rapidly
molecules move through the polymer matrix

A

Transport properties

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99
Q

suggests not a
solid-liquid phase transition but a transition from a crystalline or
semi-crystalline phase to a solid amorphous phase

A

melting point

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100
Q

______ Tg, molecular motions are frozen, and polymers are brittle
and glassy

A

below

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101
Q

____ Tg, molecular motions are activated, and
polymers are rubbery and viscous

A

above

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102
Q

analytical branch of polymer science; a technique used to determine the
molecular properties, structure, and behavior of polymers

A

Polymer characterization

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103
Q

involves a count of the number
of molecules of each species

A

number-average molecular weight, Mn

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104
Q

number-average molecular weight, Mn

A

polydispersity index (PDI)

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105
Q

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)

A

end-group analysis

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106
Q

not applicable to
polymers that lack reactive or easily
detectable end-groups.

A

End-group
Analysis

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107
Q

Properties of solutions that depend on the number of molecules present
and not on the kind of molecules

A

colligative properties

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108
Q

In applying this method, the boiling point of a
solution of known concentration is compared
to that of the solvent at the same pressure

A

Ebulliometry (Boiling Point Elevation)

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109
Q

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)

A

Cryoscopy (Freezing Point Depression)

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110
Q

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)

A

Membrane osmometry

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111
Q

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.

A

Light-Scattering Method

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112
Q

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.

A

Static light scattering

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113
Q

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

A

Light-Scattering Method

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114
Q

is defined as the measure of the opposing force of material to
flow

A

Viscosity

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115
Q

gives the relationship between viscosity and
average molecular weight

A

Mark-Houwink equation

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116
Q

most common type of
viscometer that is used for the
determination of viscosity of polymer
solution.

A

Ubbelohde
viscometer

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117
Q

an
extremely powerful method for determining the
complete molecular weight distribution and
average molecular weights

A

Gel permeation chromatography (GPC)

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118
Q

are used to purify and characterize
low-molecular-weight polymers

A

Ultracentrifuges

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119
Q

proved to be a rapid and precise method of molecular-weight
determination, often requiring as little as a half hour per sample.

A

GPC

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120
Q

a microscale property that is
largely dictated by the amorphous or crystalline portions
of the polymer chains and their influence on each other

A

Polymer morphology

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121
Q

the
polymer is allowed to react to form low molecular-weight fragments that are
condensed at liquid-air temperature

A

Mass
Spectrometry

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122
Q

an ionization
technique that uses a laser energy-absorbing matrix to
create ions from large molecules with minimal
fragmentation

A

matrix-assisted laser
desorption/ionization (MALDI)

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123
Q

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

A

Mass Spectrometry

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124
Q

a method of separation in
which gaseous or vaporized components are
distributed between a moving gas phase and fixed
liquid phase or solid adsorbent.

A

Gas Chromatography

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125
Q

an analytical method that combines the features
of gas-chromatography and mass spectrometry to
identify different substances within a test sample

A

Gas chromatography–mass spectrometry (GC–MS)

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126
Q

High Separation Efficiency
Quantitative Analysis
Wide Range of Applications

A

Gas Chromatography

127
Q

the analysis
of infrared light interacting with a
molecule. This can be analyzed in
three ways by measuring absorption,
emission and reflection.

A

Infrared Spectroscopy

128
Q

measures the
vibrations of atoms, and based on
this it is possible to determine the
functional groups.

A

IR Spectroscopy

129
Q

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

A

Fourier transform infrared spectroscopy (FTIR)

130
Q

is a
powerful analytical technique used to study the molecular
structure, dynamics, and composition of organic and inorganic
compounds

A

Nuclear Magnetic Resonance (NMR) spectroscopy

131
Q

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

A

Nuclear Magnetic Resonance (NMR) spectroscopy

132
Q

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.

A

Electron Paramagnetic
Resonance Spectroscopy

133
Q

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.

A

Ultraviolet–visible
spectroscopy

134
Q

Provides information about the
presence of specific functional groups or chromophores
within polymers.

A

Ultraviolet–
visible
spectroscopy

135
Q

a powerful qualitative and
quantitative tool with some particular advantages for the
analysis of polymers

A

Raman spectroscopy

136
Q

an analytical technique used to
study molecular vibrations in materials by measuring the
scattering of light when it interacts with a sample

A

Raman spectroscopy

137
Q

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.

A

Raman Spectroscopy

138
Q

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.

A

X-ray diffraction (XRD)

139
Q

is a
category of microscopes
that uses visible light to
magnify and image small
samples.

A

light microscope

140
Q

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

A

Polarized-light
Microscopy

141
Q

is a type of
microscopy that uses interference patterns
produced by the incoherent light scattered by
specimens to create an image

A

Phase-contrast microscopy

142
Q

powerful tool in the
study of the morphology of crystalline polymer

A

Electron Microscopy

143
Q

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

A

electron microscope

144
Q

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

A

scanning electron microscope (SEM)

145
Q

) 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

A

transmission electron microscope (TEM)

146
Q

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

A

Differential scanning calorimetry (DSC)

147
Q

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.

A

Differential
Thermal Analysis

148
Q

a sensitive balance is used to follow the
weight change of the sample as a function of
temperature

A

Thermogravimetric
Analysis

149
Q

measures the mechanical
response of a polymer system
as the temperature is changed

A

Thermomechanical
Analysis

150
Q

This is
usually done by measuring
continuously the force
developed as the sample is
elongated at constant rate of
extension.

A

Stress-Strain
Properties in
Tension

151
Q

is the maximum
stress that a material can withstand
while being stretched or pulled
before breaking.

A

Tensile strength

152
Q

material property
and is the stress corresponding to
the yield point at which the material
begins to deform plastically.

A

Yield strength

153
Q

is a mechanical property of solid
materials that measures the tensile
or compressive stiffness when the
force is applied lengthwise

A

Young’s modulus (or Young modulus)

154
Q

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

A

Shear stress

155
Q

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.

A

Flexure

156
Q

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

A

Compressive stress

157
Q

twisting of an object due to an applied torque.

A

Torsion

158
Q

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

A

fatigue

159
Q

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

A

Fatigue tests

160
Q

measure the ability of a
material to resist deformation in response
to a sudden load

A

Impact tests

161
Q

Four commonly used types of impact tests

A

Charpy, Izod, drop-weight, and
dynamic tear tests

162
Q

occurs if the material behaves elastically up to the point of failure.

A

Brittle rupture

163
Q

occurs when the specimen is permanently distorted near the
point of failure.

A

Ductile rupture

164
Q

temperature at the onset of brittleness, is usually
determined by subjecting a specimen to impact in a standardized but empirical
way.

A

brittle point

165
Q

commonly measured by tests in which a
pendulum with a massive striking edge is allowed to hit the specimen.

A

Impact strength

166
Q

In one test of tear strength, a
specimen is torn apart at a cut made
by a sharp blade

A

Tear
Resistance

167
Q

composite property
combining concepts of resistance to
penetration, scratching, marring, and
so on

A

Hardness

168
Q

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

A

Abrasion
Resistance

169
Q

defined as the
temperature at which the resin flows under a
given load on heating.

A

softening temperature

170
Q

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.

A

flammability

171
Q

ratio of the intensities of light passing through and light
incident on the specimen (transparent)

A

transmittance

172
Q

ratio of the intensities of the reflected and the incident light (opaque)

A

opaque

173
Q

one that transmit part and reflects part of the
light incident on it

A

translucent

174
Q

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

A

Color

175
Q

description of color
requires specification of three
variables

A

hue, lightness, and
saturation

176
Q

geometrically selective
reflectance of a surface responsible
for its shiny or lustrous appearance

A

Gloss

177
Q

percentage of transmitted
light that in passing through the
specimen deviates from the
incident beam by forward (2.5deg)

A

haze

178
Q

defined as the state permitting perception of objects through or
beyond the specimen

A

Transparency

179
Q

efers to the ability of a polymer material to resist the flow of
electrical current

A

Resistivity

180
Q

measure of a
material’s ability to store electric charge

A

dielectric constant

181
Q

a
measure of its ability to sustain high-voltage
differences without current breakdown

A

dielectric strength

182
Q

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

A

Arc resistance

183
Q

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

A

environmental stress
cracking

184
Q

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

A

crazing

185
Q

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

A

Vapor Permeability

186
Q

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

A

Permeability

187
Q

refers to the process of
degradation of polymers, or large molecules, due to
exposure to external factors such as sunlight,
temperature, and chemicals

A

Weathering of polymers

188
Q

suggested a
classification of polymers into two
groups: condensation (step-growth)
and addition (chain-growth) polymers

A

W. H. Carothers (1929)

189
Q

a process by which monomer
units are attached one at a time in chainlike
fashion to form a linear molecule

A

Chain-growth polymerization or addition
polymerization

190
Q

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

A

Chain-growth polymerization or addition
polymerization

191
Q

The most common
unsaturated compounds that undergo chain-growth polymerization

A

olefins

192
Q

polymerization
technique where unsaturated monomer molecules
add onto the active site on a growing polymer chain
one at a time

A

Chain-growth polymerization

193
Q

three fundamental steps of CHAIN-GROWTH
POLYMERIZATION

A

initiation,
propagation, and termination

194
Q

A chain
polymerization in which the
kinetic
-chain carriers are
radicals

A

Free Radical
Polymerization

195
Q

method of
polymerization by which a
polymer forms by the successive
addition of free
-radical building
blocks (repeat units)

A

Free
-radical polymerization

196
Q

involves the acquisition of an
active site by the monomer

A

Initiation

197
Q

initiation of free-radical
polymerization is brought about by the
addition of small quantities of
compounds called

A

initiators

198
Q

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

A

initiator

199
Q

two steps of initiation in free radical polymerization

A

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
Q

involves the dissociation of a radical initiator molecule (I) which is
easily dissociated by heat or light into two free radicals

A

Chain initiation

201
Q

involves the linear
growth of the polymer chain by
the sequential addition of
monomer units to this active
growing chain molecule

A

Propagation

202
Q

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

A

chain propagation

203
Q

involves the reaction of any two free radicals
with each other, either by combination or disproportionation

A

termination

204
Q

Two propagating chains are terminated when two radicals combine
to form an electron-pair (covalent) bond as in the reaction above

A

termination by combination (or coupling)

205
Q

reaction of the
unpaired electrons of two chains to
form a covalent bond between them

A

Combination

206
Q

This termination step involves two growing molecules that react to from
two “dead chains”

A

disproportionation

207
Q

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

A

Disproportionation

208
Q

a growing polymer chain is deactivated or terminated
by transferring its growth activity to a previously inactive species

A

chain transfer

209
Q

involve chain carriers or reactive centers that
are organic ions or charged organic groups

A

Ionic polymerizations

210
Q

type of chain growth
polymerization in which a cationic initiator transfers
charge to a monomer, which then becomes reactive

A

Cationic polymerization

211
Q

The initiation of the polymerization is accomplished by
catalysts that are ____ donors

A

proton

212
Q

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

A

cocatalyst

213
Q

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

A

Termination

214
Q

a form of chain-growth polymerization or addition
polymerization that involves the
polymerization of monomers initiated with
anions

A

Anionic polymerization

215
Q

The initiator in an anionic polymerization may be any strong
_____

A

nucleophile

216
Q

commonly used initiator systems
for anionic polymerization

A
  1. alkali metals
  2. organometallic compounds
  3. lewis bases
  4. high-energy radiation
217
Q

anionic polymerization is
sometimes called “_____” polymerization

A

living

218
Q

In polymerizations of this type, each monomer is inserted
between the growing macromolecule and the initiator

A

Coordination Polymerization

219
Q

most important group of initiators in Coordination Polymerization

A

Ziegler-Natta catalysts

220
Q

pioneers on the field of coordination polymerization in the 1950s

A

Karl Ziegler in
Germany and Giulio Natta in Italy

221
Q

Ziegler–Natta catalyst systems consist of a mixture of
the following two classes of compounds

A
  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
Q

arises because of order in the
spatial structures of polymer chains

A

Stereoregularity

223
Q

Coordination
Polymerization -
Mechanism (tactics)

A
  1. isotactic (HHHH)
  2. syndiotactic (HHHRHHHRHHHR)
  3. atactic (HHHRHHHHHR)
224
Q

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

A

Step-growth polymerization

225
Q

simply its interlinking capacity, or the
number of sites it has available for
bonding with other molecules under the
specific polymerization conditions

A

functionality

226
Q

molecular weight of the polymer chain builds
up slowly and there is only one reaction mechanism for the formation of polymer

A

step-growth polymerization

227
Q

Small molecule is eliminated at each step

A

Polycondensation

228
Q

Monomers react without the elimination of a small molecule

A

Polyaddition

229
Q

the largest volume
synthetic fiber

A

poly(ethylene terephthalate)
(PETP)

230
Q

special class of polyesters derived from carbonic acid

A

Polycarbonates

231
Q

are characterized by the
presence of amide linkages (–CONH–) on the polymer main chain

A

Polyamides, or nylons

232
Q

condensation
polymers obtained from the reaction
of dianhydrides with diamines

A

Polyimides

233
Q

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.

A

Polybenzimidazoles and polybenzoxazoles

234
Q

a type of polymer
that consists of repeating units connected by aromatic
linkers, such as benzene rings

A

Aromatic ladder polymers

235
Q

employed in the production of aminoplasts and phenoplasts,
which are two different but related classes of thermoset polymers

A

Formaldehyde

236
Q

e products of the condensation reaction between either urea (urea–
formaldehyde or UF resins) or melamine (melamine–formaldehyde or MF resins)
with formaldehyde

A

Aminoplasts

237
Q

prepared from
the condensation products of phenol or resorcinol and formaldehyde

A

Phenoplasts or phenolic (phenol–formaldehyde or PF)

238
Q

polymers consisting of
monomers joined together by ether linkages
(two carbon atoms bonded to an oxygen
atom).

A

Polyethers

239
Q

s used as electrical insulators and structural parts in the building of
engines and vehicles

A

poly(phenylene sulfide)

240
Q

may be synthesized by
the nucleophilic substitution of alkali
salts of biphenates with activated
aromatic dihalides

A

Polysulfones

241
Q

A polymerization in which a cyclic monomer yields
a monomeric unit which is acyclic or contains fewer cycles than the
monomer

A

RING-OPENING POLYMERIZATION

242
Q

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

A

Ring-opening polymerization (ROP)

243
Q

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

A

increases

244
Q

Solid polymers that tend to form
ordered regions

A

crystalline polymers

245
Q

Polymers that have no crystals at
al

A

amorphous.

246
Q

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

A

glassy state

247
Q

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

A

rubbery state

248
Q

The temperature at which the glassy
state makes a transition to rubbery state

A

glass transition temperature
Tg

249
Q

temperature where There is a diffuse transition zone between
the rubbery and liquid states for
crystalline polymers

A

flow
temperature, Tf

250
Q

_____ intermolecular forces cause higher
Tg

A

strong

251
Q

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

A

stiffening groups

252
Q

restrict
rotational motion and raise the glass transition
temperature

A

cross-links between chains

253
Q

can
restrict rotational freedom, leading to higher
glass transition temperature

A

Bulky pendant groups

254
Q

limits the packing of the chains and hence
increases the rotational motion, tending to less Tg value

A

Flexible pendant groups

255
Q

low molecular weight
and non-volatile materials added to
polymers to increase their chain
flexibility

A

Plasticizers

256
Q

Tg is _______ with
the molecular weight

A

increased

257
Q

The modulus of a polymer ______ with
increasing temperature

A

decreases

258
Q

defined
as the pressure exerted by a fluid
at equilibrium at any point of time
due to the force of gravity

A

Hydrostatic pressure

259
Q

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.

A

elastic modulus

260
Q

s the force causing the
deformation divided by the area to which the
force is applied

A

stress

261
Q

e ratio of the
change in some parameter caused by the deformation to the original value of the
parameter

A

strain

262
Q

describes tensile and compressive
elasticity, or the tendency of an object to deform along an axis
when opposing forces are applied along that axis

A

Young’s modulus (E)

263
Q

describes an
object’s tendency to shear (the deformation of shape at
constant volume) when acted upon by opposing forces

A

shear modulus or modulus of rigidity (G)

264
Q

describes volumetric elasticity, or the
tendency of an object to deform in all directions when
uniformly loaded in all directions

A

bulk modulus (K)

265
Q

describes the object’s tendency to flex
when acted upon by a moment

A

Flexural modulus (Eflex)

266
Q

a material property and
is the stress corresponding to the yield point at which the
material begins to deform plastically

A

yield strength or yield stress

267
Q

the appearance of a crack or complete
separation of an object or material into two or more pieces
under the action of stress

A

Fracture

268
Q

If a displacement develops perpendicular to the surface in fracture, it is
called

A

normal tensile crack or simply a crack

269
Q

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

A

Fracture strength, breaking
strength

270
Q

a substance that accelerates
chemical reactions without being consumed in
the process

A

catalyst

271
Q

-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

A

Extent of reaction

272
Q

relating
average functionality (f), extent of reaction (p), and average
degree of polymerization 𝑋ത
𝑛 for polycondensation reaction
carried out for a period

A

Carother’s Equation

273
Q

defined as equal to
the total number of bifunctional initially added, No
, divided by
the remaining number of molecules N after time t

A

Average degree of polymerization 𝑿n bar

274
Q

defined as the
average number of structural units per polymer molecule

A

average degree of polymerization Xn patience

275
Q

Modulus of polymers ___ with high temp, ___ Tg

A

Decreases
Low

276
Q

Pressure exerted by a fluid at equilibrium on a solid surface due to gravity

A

Hydrostatic pressure

277
Q

Effect of pressure on the mech prop of polymers

A

Elastic Modulus
Yield strength/yield stress
Fracture properties

278
Q

A stiffer matl have a ___ elastic modulus

A

Higher

279
Q

Ratio of stress over strain

A

Elastic modulus

280
Q

Types of elastic modulus

A

Young’s
Shear
Bulk
Flexural

281
Q

Tensile stress: tensile strain

A

Young’s modulus

282
Q

Aka as elastic modulus

A

Youngs modulus of elasticity

283
Q

Describes tensile and compressive elasticity

A

Youngs modulus

284
Q

Tendency of an obj to deform when opposing forces are applied to the axis

A

Young’s modulus

285
Q

Shear stress: shear strain

A

Shear modulus

286
Q

Shear modulus aka

A

Modulus of rigidity (G)

287
Q

Objects tendency to shear when opposing forces are applied

A

Shear modulus

288
Q

Describes volumetric elasticity

A

Bulk modulus

289
Q

Tendency of an obj to deform in all directions

A

Bulk modulus

290
Q

Volumetric stress: volumetric strain

A

Bulk modulus

291
Q

Tendency of an object to flex when acted upon by a moment

A

Flexural modulus (Eflex)

292
Q

High hydrostatic pressure, ___ Tg

A

High

293
Q

High elastic modulus, ___ hydrostatic pressure in ___

A

high
Tension, compression, shear

294
Q

Determine the max allowable load

A

Yield stress/strength

295
Q

Yield strength or

A

Yield stress

296
Q

The ___ the yield stress, the __ the hydrostatic pressure

A

Higher
Higher

297
Q

Appearance of crack or complete separation of an obj intk two or more

A

Fracture

298
Q

Displacement perpendiculsr to the surface

A

Normal tensile crack

299
Q

Displacement tangentially

A

Shear crack, slip band, dislocation

300
Q

Shear crack or

A

slip band, dislocation

301
Q

Stress at which specimen fails via fracture

A

Fracture strength/breaking strength

302
Q

Fracture strength is prop to

A

Yield strength

303
Q

Fracture strength or

A

breaking strength

304
Q

Maximum stress

A

Ultimate tensile strength

305
Q

___ ultimate tensile strength, high hydrostatic pressure

A

High

306
Q

Tensile strength: ___ in ductile polymers, ___ in brittle polymers

A

High, low

307
Q

Common catalysts

A

Acids, bases, enzymes, metal ions

308
Q

Important for understanding the ctrl of the growth of poly thru polycondensation reaxns

A

Carother’s eqn

309
Q

Fraction of func grps/monomers that have reacted at time t

A

Extent of reax

310
Q

Formation of infinitely large polymer network

A

Gelation

311
Q

2 parts of gelation

A

Gel
Sol

312
Q

In gelation, ___ is soluble in all non degrading solvents

A

Gel

313
Q

In gelation, ___ remains soluble and can be extracted form gel

A

Sol

Polymer engg (2 decks)

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