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Polymer Engineering Finals > Adhesive > Flashcards

Adhesive Flashcards

1
Q

Five (5) widely known theories of adhesion

A

Mechanical Theory
- Electrostatic (Electronic) Theory
- Diffusion Theory
- Wetting Theory
- Chemical Bonding

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2
Q

the action or process of adhering to a surface or
object.

A

ADHESION

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3
Q

penetration of adhesives into pores, cavities, and other surface irregularities on the surface of the substrate.

A

Mechanical Theory

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4
Q

adhesive + substrate

A

mechanical interlacking

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5
Q
  • Caused by the displacement of air at interface by adhesives
A

Mechanical Theory

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6
Q

Mechanical theory
Enhanced adhesion by

A
  • (1) mechanical interlocking,
  • (2) formation of a clean surface,
  • (3) formation of a highly reactive surface, and
  • (4) an increase in contact surface area.
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7
Q
  • Caused by surface irregularities
  • Better adhesion** at rough interface** sites
  • Applying force along the junction of smooth surface site
    causes zipper-like effect
A

Mechanical interlocking

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8
Q

adhesion takes place due to electrostatic effects between
the adhesive and the adherend.

A

Electrostatic (Electronic) Theory

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9
Q
  • Caused by the difference in electronic band structures
  • Primary explanation for the polymer-metal adhesion
A

Electrostatic (Electronic) Theory

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10
Q

adhesion is developed through
the interdiffusion of molecules in between the adhesive and
the adherend.

A

Diffusion Theory

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11
Q

Diffusion Theory applicable when both the adhesive and the
adherend are polymers with relatively _______
capable of movement

A

long-chain molecules

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12
Q

applicable when both the adhesive and the
adherend are polymers with relatively long-chain molecules
capable of movement

A

Diffusion Theory

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13
Q

process of establishing continuous contact
between the adhesive and the adherend

A

Wetting Theory

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14
Q

adhesion results from molecular
contact between two materials and the surface forces that
develop

A

Wetting Theory

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15
Q

In wetting theory, for an adhesive to wet a solid surface, the
adhesive requires a ___________
than the critical surface tension of the solid

A

lower surface tension

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16
Q

This mechanism attributes the formation of an adhesion
bond to surface chemical forces

A

Chemical Bonding

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17
Q

Chemical Bonding
(highest E to lowest)

A

Ion-ion 450
Covalent 350
Ion-dipole 33
Hydrogen bonding 24
Dipole-dipole and London Dispersion 2

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18
Q

made from naturally occurring raw materials which
includes any animal or agricultural by-products such as
organic materials.

A

NATURAL ADHESIVES

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19
Q

manufactured from man-made materials such as
polymers.

A

SYNTHETIC ADHESIVES

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20
Q

produced from materials possessing high strength and
durability

A

Structural Adhesives

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21
Q

o hold structures together and to
resist high loads without any significant deformation

A

Structural Adhesives

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22
Q

possess shear strengths that exceeds a 1000 psi and
are resistant to common operating environments

A

Structural Adhesives

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23
Q

epoxies, phenolics,
polyurethanes, acrylics, cyanoacrylates, ureaformaldehydes, and bismaleimides.

A

Structural Adhesives

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24
Q

Not required to hold substantial amount of loads.

A

Nonstructural Adhesives

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25
Q

creep under conditions of moderate load and can
degrade after long term exposure to the environment.

A

Nonstructural Adhesives

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26
Q

pressure-sensitive adhesives, hot melt, and
water emulsion adhesives

A

Nonstructural Adhesives

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27
Q

Often used together with mechanical fasteners

A

Nonstructural Adhesives

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28
Q

Also known as “holding adhesives”

A

Nonstructural Adhesives

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29
Q

Cannot be heated and softened during repeated
cycles after initial curing.

A

Thermosetting Adhesives

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30
Q

Thermosetting Adhesives
After curing and crosslinking, the adhesive bond _____________ through the application of heat

A

can
be softened

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31
Q

can generally degrade and weaken
over time due to oxidation or molecule chain session.

A

Thermosetting Adhesives

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32
Q

Thermosetting Adhesives
Cure themselves through an irreversible chemical
reaction known as

A

crosslinking

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33
Q

solvent medium for brushing and
spray applications

A

Thermosetting Adhesives

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34
Q

During curing of Thermosetting Adhesives, the crosslinking reaction occurs
between the linking of ____________ which then
forms a crosslinked structure.

A

two linear polymers

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35
Q

reactions may require heat for initiation and
completion while it can also be completed at room
temperature.

A

Crosslinking of Thermosetting Adhesives

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36
Q

they generally
do not cure when subjected to heat.

A

Thermoplastic Adhesives

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37
Q

initially in solid form that merely soften or melt when
heated.

A

Thermoplastic Adhesives

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38
Q

can either be linear or branched.

A

Thermoplastic Adhesives

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39
Q

Upon the application of the adhesive to the substrate,
the parts are joined together, and the adhesive
hardens by

A

cooling

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40
Q

ex of Thermoplastic Adhesives

A

hot-melt adhesives

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41
Q

Have unique rheological properties

A

Elastomeric Adhesives

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42
Q

Based on synthetic or naturally that possess high toughness and
elongation.

A

Elastomeric Adhesives

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43
Q

Made from polymeric resins that are capable of high
degrees of extension and compression.

A
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44
Q

Has a great ability to absorb energy and they offer
high strength in joint designs having nonuniform load

A

Elastomeric Adhesives

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45
Q

Sold as solvent solutions, water dispersions,
pressure-sensitive types, and single or multiple part
solventless liquids or pastes

A

Elastomeric Adhesives

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46
Q

Highly viscoelastic materials

A

elastomers

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47
Q

high degree of elongation, low
modulus, and high toughness

A

Elastomeric Adhesives

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48
Q

used as sealants, vibration dampers, and sound enclosures

A

elastomers

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49
Q

Produce by combining thermosetting, thermoplastic,
and elastomeric adhesives

A

Hybrid (Alloy) Adhesives

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50
Q

high temperature, rigid resins are
combined with flexible, tough elastomers or
thermoplastics to provide improved peel strength and
energy absorption

A

Hybrid (Alloy) Adhesives

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51
Q

Earliest approaches combat brittle failure which
included the development of adhesive formulations
by blending a flexibilizing resin into the body of
another resin (resin + resin)

A

Hybrid (Alloy) Adhesives

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52
Q

Nitrile-phenolic, epoxy-polysulfide, and other resin
blends provided resilience and toughness due to the
elastomeric ingredients in the formulation

A

Hybrid (Alloy) Adhesives

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53
Q

Due to the elastomeric component, the glass
transition temperature (Tg) is ____________ and the
resistance to elevated temperatures and chemicals is
also weakened

A

lowered

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54
Q

could
significantly limit the characteristics of
the adhesive in the particular
application

A

method of curing

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55
Q

A type of reaction wherein a side product is also produced, which is
commonly water

A

Condensation reaction

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56
Q

considered the oldest of the
synthetic adhesives in Condensation reaction

A

phenolic and amino resins

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57
Q

Usually necessary to also apply pressure to overcome the deleterious effects
of the volatile by-products

A

phenolic and amino resins

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58
Q

No formation of by-products.

A

Addition reaction

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59
Q

Includes polyesters, epoxies, urethanes, cyanoacrylates, anaerobics, and
radiation curable polymers.

(majority of elastomers and acrylics)

A

Addition reaction

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60
Q

Only contact pressure is necessary for these adhesives, and so they are well
suited for bonding large articles.

A

Addition reaction

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61
Q

epoxy, polyurethane, modified
acrylic, cyanoacrylate, and anaerobic systems

A

cure by chemical reaction

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62
Q

cure by chemical reaction

A
  1. Single component systems
  2. Multiple component systems
63
Q

Composed of two or more components
that must be kept separate until just before
the bonding process

A

Multiple part adhesive systems

64
Q

Epoxies, polyurethanes, acrylics, phenolics,
and silicones

A

multiple systems

65
Q

Multiple part adhesive systems

A
  1. ratio
  2. mix
  3. dispersed
66
Q

Typically consist of two or more premixed
components

A

Single component systems that cure via catalyst or hardener

67
Q

In Single component systems that cure via catalyst or hardener, curing agent or hardener is
incorporated with the

A

resin base and all the
other fillers and additives.

68
Q

Requires refrigerated conditions and have
limited shelf life

A

Single component systems that cure via catalyst or hardener

69
Q

epoxy, epoxy hybrids, polyurethane,
polyimide, polybenzimidazole, phenolic, and
phenolic hybrids

A

Single component systems that cure via catalyst or hardener

70
Q

Use the humidity in the ambient air to react
with the base resin in the adhesive
formulation

A

. Moisture curing adhesives

71
Q

Generally can cure completely at room
temperature

A

Moisture curing adhesives

72
Q

common
single component adhesives that cure by
reacting with environmental moisture

A

Polyurethanes and silicones

73
Q

Can cure by exposure to radiation

A

UV/light curing adhesives

74
Q

employed to many assembly
operations where high throughput or
delicate components are prevalent

A

UV/light curing adhesives

75
Q

Require the presence of the correct
wavelengths of light at sufficient intensity to
produce strong structural bonds

A

UV/light curing adhesives

76
Q

UV/light curing adhesives use _____________ to activate the free
radical curing mechanism

A

photoinitiators

77
Q

Single component adhesives that can cure
via a chemical reaction mechanism that
uses the active or live metal ions on the
substrate as a catalyst.

A

Adhesives catalyzed by the substrate

78
Q

Also called anaerobic adhesives because
they cure only in the absence of oxygen.

A

Adhesives catalyzed by the substrate

79
Q

Adhesives catalyzed by the substrate First developed during the 1950s and 1960s
by

A

Loctite Corporation

80
Q

Cure at a fast rate depending on the
substrate. Cure speeds range from several
minutes to 24 hrs

A

Adhesives catalyzed by the substrate

81
Q

completely formulate the adhesive system,
including resins, fillers, curing agents, etc., in the
liquid state and then converting it into a solid
state that is not completely cured.
(single component)

A

. Adhesives in solid form (tape, film, powder)

82
Q

hardening process
is usually accompanied by extruding,
calendering, or casting the adhesive formulation
into thin films that are typically 5–10 mils thick

A

. Adhesives in solid form : tape, film

83
Q

Usually applied to both substrates either by
spray or roll coating.

A

Contact adhesives

84
Q

Their tackiness is permanent and there is no
optimal time range when the substrates
must be joined.

A

Pressure-sensitive adhesives

85
Q

Generally, have relatively high shear and
peel strengths.

A

Contact adhesives

86
Q

Usually based on elastomer or
thermoplastic solvent solutions.

A

Pressure-sensitive adhesives

87
Q

Mostly applied to plastic, paper, foil or
fibrous material as suitable backings.

A

Pressure-sensitive adhesives

88
Q

Also known as solvent activated adhesives.

A

Reactivatable adhesives

89
Q

Applied to a substrate via solvent coating
and then dried to a non-tacky state

A

Reactivatable adhesives

90
Q

Labels, nameplates, stamps, etc. are
common applications

A

Reactivatable adhesives

91
Q

Used for their mechanical interlocking
ability

A

Resinous solvent adhesives

92
Q

Formulated with a relatively rigid, tough
thermoplastic resin.

A

Resinous solvent adhesives

93
Q

The substrate is generally porous. Once applied, the solvent evaporates into the air and through the substrate so that the
adhesive resin interlocks the pores of the
substrate together.

A

Resinous solvent adhesives

94
Q

A type of adhesive that can harden by
cooling from a melt condition
(glue gun)

A

Hot melt adhesives

95
Q

They are generally thermoplastic adhesives
that soften and melt when heated, and they
harden following subsequent cooling.

A

Hot melt adhesives

96
Q

ethylene and vinyl
acetate copolymers, polyvinyl acetates,
polyethylene, amorphous polypropylene,
block copolymers (styrene butadiene
rubber), polyamides, and polyester

A

Hot melt adhesives

97
Q

The difference between paste and liquid
adhesive lies mainly in

A

viscosity and
method of application

98
Q

free flowing fluids that
can be applied in thin films

A

Liquid adhesives

99
Q

heavily bodied, often
thixotropic systems that must be applied
with spreading equipment such as a trowel
or caulking gun

A

Paste adhesives

100
Q

Use organic solvent to reduce viscosity for
easier application

A

Solvent-based adhesives

101
Q

simply a carrier for the
‘‘solids’’ part of the adhesive

A

solvent

102
Q

applied by spraying,
dipping, or brushing, but the solvent must
be driven off before the joint is assembled

A

Solvent-based adhesives

103
Q

may be
chemically crosslinked, usually through the
application of a curing agent and heat

A

Solvent-based adhesives

104
Q

Usually emulsions of thermoplastic resins

A

Water-based adhesives

105
Q

evaporated through the
air or diffused into the porous substrate

A

water carrier

106
Q

they are
formulated as contact, pressure sensitive,
reactivatable, and resinous adhesive
systems

A

Water-based adhesives

107
Q

Most widely used emulsion-based adhesive

A

polyvinyl acetate-polyvinyl alcohol
copolymer

108
Q

known as ‘‘white’’ glue or
wood glue.

A

polyvinyl acetate-polyvinyl alcohol
copolymer

109
Q

Common forms of ____________ are tape
or film, powder, or solid shape forms.

A

solid adhesives

110
Q

The main advantages of these single
component adhesives are that _______________ is not required, and they can be
applied uniformly to a substrate with little or
no waste.

A

metering
and mixing

111
Q

Both thermoplastic and thermosetting
adhesives can be formulated as

A

solid form

112
Q

used loosely and
interchangeably for adhesives in sheet
form.

A

Tapes or films

113
Q

Supported on a web of paper, nonwoven
fabric, or on open weave scrim of glass
cotton or nylon.

A

Tapes or films

114
Q

A single component system that requires
no metering

A

Tapes or films

115
Q

Must be first heated or solvent-activated to
be made liquid and flowable

A

Powdered adhesives

115
Q

eliminate
proportioning and mixing errors

A

Powdered adhesives

116
Q

uniform distribution over large assemblies
is difficult.

A

Powdered adhesives

117
Q

formulated
with thermoplastic resins

A

Hot melt forms

118
Q

dependent on development costs and
volume requirements

A

Adhesive price

119
Q

film or powder form require more ________
than liquid or paste types and are usually more expensive.

A

processing

120
Q

According to Cost

A

Efficiency of coverage
➢ Ease of application and processing equipment needed
➢ Total processing time
➢ Cost of labor for assembly and inspection of the bonded parts
➢ Waste of adhesive contributes to material costs and environmental costs for
disposal
➢ Amount of rejected material as compared with other methods of joining

121
Q

metal adhesives, wood adhesives, and vinyl adhesives
refer to the _____ to which they will bond

A

substrates

122
Q

Depending on _______________ can be applied via the
methods

A

viscosity,
liquid adhesives

123
Q

Heavily bodied adhesive pastes and mastics
are

A

extrudable

124
Q

Heavily bodied adhesive pastes and mastics
are applied by

A

syringe, caulking gun, or pneumatic pumping
equipment

125
Q

Depending on viscosity,
liquid adhesives can be applied via the following
methods:

A

➢ Spraying
➢ Brushing
➢ Trowelling

126
Q

Coating methods include

A

roller coating
blade/knife coating
flexo-roller
gravure cylinder

127
Q

Laminating adhesives for film and paper structures are
generally required to be applied

A

over the entire
substrate surface,

127
Q

pressure sensitive adhesives
applied to

A

label stock

128
Q

heat-seal coating applied
to

A

lidding stock

129
Q

ability of an adhesive to create a
durable and reliable bond between two
surfaces

A

Bond Strength

130
Q

There are two important aspects to bond
strength

A

resistance of the bonded
substrates to being peeled apart
resistance to the application of a shear force

131
Q

Three key factors significantly impact bond
strength

A

surface preparation
adhesive properties
substrate material characteristics

132
Q

Contaminants such as oils, grease, dust, or oxides can inhibit
adhesion.

A

Cleanliness

133
Q

A rough surface provides more area for the adhesive to bond
to, enhancing mechanical interlocking and increasing bond
strength.

A

Surface Roughness

134
Q

Chemical treatments or primers can modify the surface
properties of substrates to promote adhesion.

A

Surface Activation

135
Q

Different types of adhesives, such as epoxies, cyanoacrylates,
polyurethanes, or acrylics, have unique chemical compositions that
affect their adhesion mechanisms and bond strength.

A

Chemical Composition

136
Q

Low-viscosity adhesives penetrate into surface
irregularities ______________, while high-viscosity adhesives
______________ to achieve intimate contact.

A

more effectively , require more pressure

137
Q

time required for the adhesive to reach its maximum
strength affects the bond formation process.

A

Cure Time

138
Q

Some adhesives exhibit changes in viscosity, cure rate, or
strength with temperature variations

A

Temperature Sensitivity

139
Q

e compatibility between the adhesive and substrate materials
influences bond strength

A

Material Compatibility

140
Q

Substrates with higher surface energy promote better wetting
and adhesion compared to low-energy substrates.

A

Surface Energy

141
Q

Porous substrates may absorb the adhesive, leading to reduced
bond strength

A

Porosity

142
Q

applies a pulling force directly opposite the
bonded area, attempting to separate the materials in a
straight line.

A

Tensile Test

143
Q

maximum force a bond
can withstand before breaking and the elongation
(stretching) that occurs before failure.

A

Tensile Test

144
Q

ASTM Tensile Test Methods

A

ASTM Method
D2095

145
Q

applies a force parallel to the bonded area,
trying to make the materials slide past each other.

A

Shear Test

146
Q

determine the shear strength
of the bond, which is the force required to cause this
sliding fracture

A

Shear Test

147
Q

Shear Test device

A

ASTM D1002

148
Q

This test evaluates the bond strength by applying a force
perpendicular to the bonded interface, similar to a tensile
test.

A

Cleavage Test

149
Q

these tests are
based on adherends that are not deformed significantly
during the measurement.

A

Cleavage Test

150
Q

test measures the
adhesive strength of the bond, indicating how well the
adhesive itself holds the materials together

A

Cleavage Test

151
Q

Peel Test device

A

ASTM D1876.

152
Q

A cleavage tests. However, at least one of the
adherends is made from a flexible material that could be plastically deformed during the measuremen

A

Peel tests

Polymer Engineering Finals (12 decks)

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