Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Polymer engineering > Molecular origin of Polymer Properties > Flashcards

Molecular origin of Polymer Properties Flashcards

1
Q

is a macromolecule
(long molecules) built of small
covalently bonded units called
monomers

A

polymer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

These small units are repeated
throughout the macromolecule
chain.

A

mer/monomers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

The macromolecules are bonded
together by

A

weak Van der Waals
and hydrogen (secondary) bonds,
or additional covalent crosslinks

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Most polymers are

A

organic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Each C atom has _____ electrons that participate in covalent bonding, each H atom
has _______ bonding electron

A

4, 1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

exists when each of the two bonding atoms contributes one
electron

A

single bond

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

between two carbon atoms involve the sharing of two and
three pairs of electrons, respectively

A

double, triple bhond

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

▪ Molecules that have double, and triple covalent bonds are termed

A

unsaturated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

each carbon atom is not bonded to the maximum (four) other atoms

A

unsaturated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

molecule that combines with other molecules of the
same or different type to form a polymer

A

monomer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q
A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

The structure of the repeating unit of a polymer is __________to that of the monomer molecule(s

A

essentially that or
closely related

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

low-molecular-weight polymer

A

oligomer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

If the ethylene gas is reacted under appropriate conditions, it will transform to

A

polyethylene (PE)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

specifies the length of the polymer molecule.

A

degree of polymerization

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

indicates the number of repeating units strung
together in the polymer chain (molecule)

A

The subscript designation, n

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

The subscript designation, n, is known as

A

degree of polymerization

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

normally required for a material to
develop useful properties and before it can be appropriately described as a
polymer

A

A high degree of polymerization

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

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

A

Molecular weight

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

The relation between degree of polymerization and molecular weight M of
the same macromolecule

A

M= (DP)Mo

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

CLASSIFICATION OF POLYMERS BASED ON ORIGIN

A

Natural and synthetic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Wood, rubber, cotton, leather, wool, silk,
protein, enzymes, starches, cellulose

A

Natural polymers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Fibers, elastomers, plastics, adhesives

A

synthetic polymers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

CLASSIFICATION BASED ON POLYMER STRUCTURE

A

LINEAR, BRANCHED OR CROSS-LINKED, NETWORK VS. FUNCTIONALITY

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

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

A

functionality of a molecule

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

A molecule may be classified as ______________ depending on whether it has one, two, or greater
than two sites available for linking with other molecules.

A

monofunctional, bifunctional, or
polyfunctional

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

those in which the
repeat units are joined together end to
end in single chains.

A

Linear polymers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Some of the common examples of
linear polymers

A

polyethylene, PVC,
polystyrene, and polyamides.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Linear polymers are generally more

A

rigid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

have side chains or branches
growing out from the main chain

A

Branched polymers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

The side chains or
branches in branched polymers are made of the ______repeating units as the
main polymer chains

A

same

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

For a polymer to classify as branched polymer the side chains or branches should comprise of a minimum

A

one complete monomer unit

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

One of the most common example of branched polymer

A

LDPE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

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

A

Crosslinked polymers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

tend to be permanent in
nature.

A

crosslinks

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Once the crosslinks between the
chains develop the polymer then
becomes

A

thermoset

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Common examples of crosslinked polymers

A

Bakelite, melamine, epoxies, bulk molding
compounds, rubber, and various
adhesives

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

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

A

network polymers.

39
Q

the epoxies, polyurethanes, and
phenol-formaldehyde belong to t

A

network polymers

40
Q

CLASSIFICATION BASED ON POLYMER STRUCTURE

A

AMORPHOUS OR CRYSTALLINE

41
Q

material
exhibits organized and tightly packed molecular
chains.

A

crystalline polymer

42
Q

In terms of properties, they have good strength & wear, and good chemical resistance, but they
typically lack in impact resistance

A

crystalline polymer

43
Q

Examples of crystalline polymers include

A

polyethylene, polyacrylonitrile, poly(ethylene
terephthalate), and polytetrafluoroethylene.

44
Q

polymers that have no
crystalline regions and no uniformly packed
molecules

A

Amorphous polymers

45
Q

polymers that are composed of amorphous regions where molecules are randomly arranged.

A

Amorphous polymers

46
Q

good examples of amorphous polymers

A

Natural rubber latex and styrene-butadiene rubber

47
Q

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

A

degree of crystallinity

48
Q

CLASSIFICATION BASED ON POLYMER STRUCTURE

A

HOMOPOLYMER OR COPOLYMER

49
Q

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

A

homopolymer

50
Q

produce a
polymer that has increased mechanical properties

A

homopolymers

51
Q

a polymer made up of more
than one type of monomer unit.

A

copolymer

52
Q

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

A

copolymers

53
Q

Copolymers produced are
sometimes also referred

A

biopolymers

54
Q

The purpose of creating a copolymer is to

A

manufacture a polymer with more desirable
properties

55
Q

There are three other copolymer structures, other than random

A

alternating, block, and
graft copolymer structures

56
Q

the two mers
alternate in a regular fashion along the polymer chain

A

alternating copolymer

57
Q

linear polymer with one or more long
uninterrupted sequences of each mer in the chain

A

block copolymer

58
Q

a branched copolymer with a backbone of one type of mer and one or more side chains of another mer

A

graft copolymer

59
Q

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

A

fibers

60
Q

They are characterized by high modulus, high
tensile strength, and moderate extensibilities

A

fibers

61
Q

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

A

elastomers

62
Q

polymers that have
viscosity and elasticity and therefore
are known as viscoelasticity.

A

elastomers

63
Q

They inherit the unique property of
regaining their original shape and
size after being significantly
stretched

A

elastomers

64
Q

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

A

plastic

65
Q

CLASSIFICATION BASED ON POLYMERIZATION
MECHANISM

A

CONDENSATION POLYMERS
ADDITION POLYMERS

66
Q

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

67
Q

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 such as water
or methanol molecule

A

Condensation polymers

68
Q

The by-products of condensation are normally referred to as

A

condensate

69
Q

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

A

Addition polymers

70
Q

CLASSIFICATION OF POLYMERS ACCORDING TO THERMAL PROCESSING BEHAVIOR

A

THERMOPLASTICS
THERMOSETS

71
Q

Plastics that soften when heated and
become firm again when cooled

A

THERMOPLASTICS

72
Q

This is
the more popular type of plastic because
the heating and cooling may be repeated
and the thermoplastic may be reformed

A

THERMOPLASTICS

73
Q

Most linear polymers and those having
some branched structures with flexible
chains are

A

thermoplastic

74
Q

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

A

THERMOSETS

75
Q

heated, undergoes a chemical
change to produce a cross-linked, solid polymer.

A

A thermoset

76
Q

Thermosets usually exist initially as liquids called

A

prepolymers

77
Q

CLASSIFICATION BASED ON PREPARATIVE TECHNIQUE

A

BULK POLYMERIZATION
SOLUTION POLYMERIZATION
SUSPENSION POLYMERIZATION
EMULSION POLYMERIZATION

78
Q

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

A

bulk polymerization

79
Q

The monomer undergoes polymerization, at the end of which a solid mass is removed as
the polymer product

A

bulk polymerization

80
Q

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

A

Solution polymerization

81
Q

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.

A

Suspension polymerization

82
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

83
Q

BULK PROPERTIES OF POLYMERS

A

TENSILE STRENGTH
YOUNG’S MODULUS OF ELASTICITY
TRANSPORT PROPERTIES
PURE COMPONENT PHASE BEHAVIOR

84
Q

quantifies how much stress the
material will endure before failing

A

tensile strength of a material

85
Q

Tensile strength ___________ with
polymer chain length

A

increases

86
Q

Quantifies the
elasticity of the polymer.

A

YOUNG’S MODULUS OF ELASTICITY

87
Q

defined as the ratio of rate of
change of stress to strain.

A

YOUNG’S MODULUS OF ELASTICITY

88
Q

relate to how rapidly
molecules move through the polymer matrix

A

Transport properties

89
Q

Transport properties are very important in many applications of polymers for

A

films and membranes.

90
Q

PURE COMPONENT PHASE BEHAVIOR

A

➢MELTING POINT
➢ GLASS TRANSITION

91
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

92
Q

crucial physical parameter for polymer manufacturing, processing, and use

A

glass-transition temperature (Tg)

93
Q

molecular motions are frozen, and polymers are brittle and glassy

A

Below Tg

94
Q

molecular motions are activated, and
polymers are rubbery and viscous

A

Above Tg

Polymer engineering (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions