MOLECULAR ORIGIN OF POLYMER PROPERTIES

Question 1

The macromolecules are bonded together by weak____ and ____, or additional covalent crosslinks

Answer 1

Van der Waals; hydrogen (secondary) bonds

Question 2

Molecules that have double, and triple covalent bonds are termed ____—that is, each carbon atom is not bonded to the maximum (four) other atoms.

Answer 2

unsaturated

Question 3

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

Answer 3

saturated

Question 4

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

Answer 4

monomer

Question 5

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

Answer 5

oligomer

Question 6

The ____ specifies the length of the polymer molecule.

Answer 6

degree of polymerization

Question 7

A ____ degree of polymerization is normally required for a material to
develop useful properties and before it can be appropriately described as a
polymer.

Answer 7

high

Question 8

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

Answer 8

Molecular weight

Question 9

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

Answer 9

Natural Polymers

Question 10

Fibers, elastomers, plastics, adhesives

Answer 10

Synthetic Polymers

Question 11

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

Answer 11

functionality

Question 12

Are 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.”

Answer 12

Linear polymer

Question 13

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.

Answer 13

Branched polymers

Question 14

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

Answer 14

crosslinked polymers

Question 15

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

Answer 15

network polymers

Question 16

A _____ means that the material exhibits organized and tightly packed molecular chains.

Answer 16

crystalline polymer

Question 17

Are polymers that have no crystalline regions and no uniformly packed molecules.

Answer 17

Amorphous polymers

Question 18

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

Answer 18

degree of crystallinity

Question 19

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

Answer 19

homopolymer

Question 20

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

Answer 20

copolymer

Question 21

Types of copolymer

Answer 21

Random
Alternating
Block
Graft

Question 22

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

Answer 22

Fibers

Question 23

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

Answer 23

Elastomers

Question 24

Elastomers are polymers that have viscosity and elasticity and therefore are known as ______.

Answer 24

viscoelasticity

Question 25

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

Answer 25

plastic

Question 26

Types of plastic

Answer 26

1 - Polyethylene Terephthalate
2 - High Density Polyethylene
3 - Polyvinyl Chloride
4 - Low Density Polyethylene
5 - Polypropylene
6 - Polystyrene
7 - Bisphenol A and others

Question 27

Are formed from a series of reactions, in which any two species can react at any time leading to a larger molecule.

Answer 27

Condensation polymers

Question 28

Condensation polymerization is a form of a step-growth polymerization where smaller molecules or monomers react with each other to form larger structural units while releasing by-products such as water or methanol molecule. The by-products are normally referred to as ____.

Answer 28

condensate

Question 29

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

Answer 29

Addition polymers

Question 30

Plastics that soften when heated and
become firm again when cooled. This is
the more popular type of plastic because the heating and cooling may be repeated.

Answer 30

Thermoplastic

Question 31

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

Answer 31

Thermoset

Question 32

A thermoset when heated, undergoes a chemical change to produce a cross-linked, solid polymer. Thermosets usually exist initially as liquids called ___

Answer 32

prepolymers

Question 33

In ____, only the monomer (and possibly catalyst and initiator, but no solvent) is fed into the reactor. The monomer undergoes polymerization, at the end of which a solid mass is removed as the polymer product.

Answer 33

bulk polymerization

Question 34

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

Answer 34

Solution polymerization

Question 35

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.

Answer 35

Suspension polymerization

Question 36

Is 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.

Answer 36

Emulsion polymerization

Question 37

Quantifies how much stress the
material will endure before failing.

Answer 37

Tensile strength

Question 38

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

Answer 38

Young’s Modulus

Question 39

A transition from a crystalline or semi-crystalline phase to a solid amorphous phase.

Answer 39

melting point

Question 40

_____ Tg, molecular motions are activated, and polymers are rubbery and viscous.

Answer 40

Above

Question 41

____Tg, molecular motions are frozen, and polymers are brittle and glassy.

Answer 41

Below