Polymer Characteristics

Question 1

fractures while deforming elastically.

Answer 1

Brittle polymer

Question 2

the initial deformation is elastic, then followed by yielding and a region of plastic deformation.

Answer 2

Plastic

Question 3

is totally elastic; large recoverable strains produced at low stress lev

Answer 3

Elastomer

Question 4

corresponds to the stress at which fracture occurs

Answer 4

tensile strength

Question 5

property of materials that exhibit both viscous and elastic characteristics when undergoing deformation.

Answer 5

Viscoelasticity

Question 6

determines whether the deformation is elastic or viscous.

Answer 6

rate of strain

Question 7

formation prior to cracking

Answer 7

Craze

Question 8

during crazing there is plastic deformation causing formation of ______ and ________

Answer 8

Microviods, fibrillar bridges

Question 9

the capability of a material to withstand a suddenly applied load and it is expressed in terms of energy

Answer 9

Impact strength

Question 10

is the weakening of a material caused by repeatedly applied loads.

Answer 10

Fatigue

Question 11

the energy required to tear apart a cut specimen such as polymers

Answer 11

Tear strength

Question 12

represents a material’s resistance to scratching, penetration, dents and so on.

Answer 12

Hardness

Question 13

_______ of polymers is a process associated with partial alignment of their molecular chains.

Answer 13

Crystallization

Question 14

These chains fold together and form ordered regions called ______

Answer 14

Lamellae

Question 15

occurs at relatively low

stress levels on the stress–strain curve.

Answer 15

Mechanism of Elastic Deformation

Question 16

chain molecules in amorphous regions elongates in the direction of the applied tensile stress.

Answer 16

Mechanism of Elastic Deformation

Question 17

is the amount of crystallized regions in a material.

Answer 17

Degree of Crystallinity

Question 18

Corresponds to the neck extension process

Answer 18

Predeformation by drawing

Question 19

An important stiffening and strengthening technique that is employed in the production of fibers and films

Answer 19

Predeformation by drawing

Question 20

_________ of semicrystalline polymers can lead to an increase in the percent crystallinity and crystallite size and perfection.

Answer 20

Heat-treating or annealing

Question 21

eliminates internal stresses and ensures better mechanical and thermal properties.

Answer 21

Heat-treating (or annealing)

Question 22

Any rubbery material composed of long chainlike molecules, or polymers, that are capable of recovering their original shape after being stretched to great extents.

Answer 22

Elastomers

Question 23

Is a chemical process used to harden rubber.

Answer 23

Vulcanization

Question 24

It works by forming cross-links between sections of polymer chain which results in increased rigidity and durability.

Answer 24

Vulcanization