ch 17; adhesive bonding

Question 1

what’s adhesive bonding

Answer 1

joining 2+ close together parts with filler material (join by surface attachment)

Question 2

Adhesive bonding is used in a range of bonding and {} applications for joining similar and {} materials e.g. {} and {}

Answer 2

sealing
dissimilar
metals, plastics, ceramics, wood, paper, carboard

Question 3

without special surface treatments, 2 materials that are challenging to bond with adhesion.
metals with a smooth, non-p{} surface such as { } are also difficult to bond unless properly prepared

Answer 3

1) glass, polyethylene, teflon
non porous
stainless steel

Question 4

define adhesive

Answer 4

non metallic filler material, usually a polymer

Question 5

structural adhesives are capable of forming strong {} between strong, {} adherends. They’re widely used in bonding flexible and {} adherends

Answer 5

joints
rigid
dissimlar

Question 6

structural adhesives are strongest in {}, {} and {}
[forces]

Answer 6

compression
uniaxial tension
shear

Question 7

elastomeric meaning

Answer 7

elastomer (polymer with elastic and viscous characteristics) properties

Question 8

viscous meaning
when force applied, material exhibits an {i } causing it to slowly {} and {} immediate shape changes, think of honey moving

Answer 8

resistance to flow or deformation
internal resistance
deform
resist

Question 9

define curing

Answer 9

chemical process that cross-links polymer chains== toughening and hardening by heat or UV

Question 10

curing in adhesive bonding involves changing the {} properties of the adhesive, from {} to {}, by chemical reaction, to accomplish surface {} of parts.

Answer 10

physical
liquid
solid
attachment

Question 11

3 methods to cure adhesives

Answer 11

curing methods: 1) chemical reaction between 2 components of the adhesive (e.g. epoxies)
2) heating of adhesive
3) use of UV
4) application of pressure

Question 12

3 basic categories of commercial adhesives

Answer 12

1) natural (e.g. starch, collagen)
2) inorganic (e.g. sodium silicate)
3) synthetic (e.g. thermoplastic and thermosetting polymers like epoxies and acrylics)

Question 13

sodium silicate is a(n) {} adhesive, known as {} glass. This adhesive is used in {low,high} temperature applications and for bonding materials like {} and glass

Answer 13

inorganic
water
high
ceramics

Question 14

2 thermosetting polymers

Answer 14

epoxy resin [adhesives, coatings, composite materials –strong mechanical property, chemical resistance]
vulcanized rubber (elastomer and thermosetting polymer)
silicone resin [sealants, coatings, adhesives; –heat resistance]

Question 15

vulcanized rubber combines the flexibility and resilience of {} with the durability and stability of {} .

Answer 15

elastomer
thermoset

Question 16

2 thermoplastics

Answer 16

acrylics (PMMA) [heated, melted reshaped multiple times no severe degradation of properties]
polystyrene (PS)– foam packaging materials like Styrofoam, disposable cutlery, CD cases

Question 17

important precondition for success of an adhesive bonding operation?

Answer 17

very clean surfaces for adherents

Question 18

immediately prior to adhesive application, {s } is often required.

Answer 18

special surface preparation

Question 19

special surface preparation involves…

Answer 19

1) removing contaminants e.g. oil, dust, rust; using solvents/cleaners
2) roughening the surface (through mechanical abrasion e.g.grinding, sandblasting)
3) modify chemical composition e.g. applying primers to surface to improve chemcial compatibility

Question 20

what does roughening the surface do for adhesive bonding

Answer 20

enhances adhesives ability to grip surface by increasing surface area available for bonding

Question 21

methods to apply adhesives in industrial production operations

Answer 21

1) manual brushing
2) manual rollers
3) spraying
4) roll coating

Question 22

4 joining methods

Answer 22

welding
adhesives
soldering
brazing
mechanical fastening

Question 23

define:
mechanical fastening
welding
brazing
soldering

Answer 23

1) using screws, bolts, clamps, physically holds parts together; reliability and ease of assembly and disassembling
2) melting base materials to create strong permanent bond e.g MIG welding, arc welding
3)filler metal with lower melting point than base metals, filler metal melted and drawn into joint by capillary action, strong bond no melting of base materials
4) like brazing but at lower temps, uses filler metal to join parts, used in electronics

Question 24

3 advantages of adhesive bonding compared to alternative joining methods

Answer 24

1) applicable to wide variety of materials
2) fragile parts can be joined
3) low curing temperatures
4) bonding over entire surface area of joint

Question 25

some adhesives are flexible after {}, permitted them to tolerate {} encountered in service

Answer 25

curing strains

Question 26

3 limitations in adhesive bonding

Answer 26

1) not as strong as other techniques 2)adhesive must be compatible with the adherent materials 3) surfaces to be bonded must be very clean 4) curing times can limit production rate 5) hard to inspect the bond