MOLECULAR ORIGIN OF POLYMER PROPERTIES Flashcards by Ming Ming

Q

These small units are repeated
throughout the macromolecule
chain

A

POLYMERS

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Q

macromolecule or long molecules

A

POLYMERS

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Q

built of small
covalently bonded units called
monomers

A

POLYMERS

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Q

Greek word for part

A

“mer” from meros

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Q

▪ The macromolecules are bonded
together by

A

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

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Q

repeating unit of (image p3)

A

polyethylene (PE)

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Q

poly

A

many

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Q

mer

A

repeat unit

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Q

repeating unit of (image p3)

A

polyvinyl chloride (PVC)

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Q

repeating unit of (image p3)

A

polypropylene (PP)

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Q

(image p4) commodity thermoplastics

A

polypropylene

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Q

(image p4) commodity thermoplastics

A

polyacetylene

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Q

(image p4) commodity thermoplastics

A

poly(p-phenylene vinylene)

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Q

(image p4) commodity thermoplastics

A

polythiophene

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Q

(image p4) commodity thermoplastics

A

polyphenylene sulfide

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Q

(image p4) commodity thermoplastics

A

polyanilines

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Q

(image 5) biomedical applications

A

polycarbonate (diphenyl carbonate)

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Q

(image 5) biomedical applications

A

polymethyl methacrylate

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Q

(image 5) biomedical applications

A

silicone polymers

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Q

(image 5) biomedical applications

A

polyvinylidene chloride

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Q

(image 5) biomedical applications

A

polyindene

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Q

(image 5) biomedical applications

A

polyvinyl pyrrolidone

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Q

(image 5) biomedical applications

A

coumarone polymer

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Q

Most polymers are _________, and formed from __________ molecules

A

organic , hydrocarbon

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no. electrons in each C atom that participate in covalent bonding

4 electrons

no. bonding electron/s in each H atom

1 bonding electron

A single covalent bond exists when

each of the two bonding atoms contributes one electron

involve the sharing of two and three pairs of electrons

Double and triple bonds

Molecules that have double, and triple covalent bonds are termed

unsaturated

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

unsaturated (double, and triple bonds)

all bonds are single ones

a saturated hydrocarbon

no new atoms may be joined without the removal of others that are already bonded

a saturated hydrocarbon

(image 7)

Methane , CH4

(image 7)

Ethane , C2H6

(image 7)

Propane , C3H8

(image 7)

hydrocarbon ethylene , C2H4

(image 7)

acetylene , C2H2

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

monomer

The structure of the repeating unit of a polymer is essentially that or _____________ to that of the ____________ molecule(s).

closely related , monomer

monomer for polyacrylonitrile

Acrylonitrile, CH2=CHCN

(image 8)

Acrylonitrile, CH2=CHCN

Monomer for polyethylene

Monomer for polyvinyl chloride

Monomer for polyisobutylene

Monomer for polystyrene

Monomer for polycaprolactam (6-nylon)

Monomer for polyisoprene (natural rubber)

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

oligomer

oligomer of polyethylene

hexatriacontane

(image 10)

hexatriacontane

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

polyethylene (PE) , solid polymeric material

transformation of ethylene gas to polyethylene (PE) begins when

an active center is formed by the reaction between an initiator or catalyst species (R.) and the ethylene monomer

an active center is formed by the

reaction between an initiator or catalyst species (R.) and the ethylene monomer

(image 11)

formation of an active center

The polymer chain then forms by the ____________ of monomer units to this actively growing chain molecule.

sequential addition

repeat unit of polymer (image 12)

polytetrafluoroethylene (PTFE)

repeat unit of polymer (image 12)

polystyrene (PS)

repeat unit of polymer (image 13)

poly(methyl methacrylate) PMMA

repeat unit of polymer (image 13)

phenol-formaldehyde (bakelite)

repeat unit of polymer (image 13)

poly(hexamethylene adipamide) nylon 6,6

repeat unit of polymer (image 13)

poly(ethylene terephthalate) PET, a polyester

repeat unit of polymer (image 13)

polycarbonate (PC)

specifies the length of the polymer molecule.

degree of polymerization

subscript designation, n, indicates the

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

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

high degree of polymerization

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

Molecular weight

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

M = (DP)Msubs0

FIVE CLASSIFICATION BASED ON

- origin - polymer structure - polymerization mechanism - thermal processing behavior - preparative technique

CLASSIFICATION OF POLYMERS BASED ON ORIGIN

NATURAL VS. SYNTHETIC

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

natural polymers

Synthetic Polymers

✓ Fibers, elastomers, plastics, adhesives

CLASSIFICATION BASED ON POLYMER STRUCTURE

A. LINEAR, BRANCHED OR CROSS-LINKED, NETWORK VS. FUNCTIONALITY B. AMORPHOUS OR CRYSTALLINE C. HOMOPOLYMER OR COPOLYMER D. FIBERS, PLASTICS, OR ELASTOMERS

CLASSIFICATION BASED ON POLYMERIZATION MECHANISM

CONDENSATION POLYMERS ADDITION POLYMERS

CLASSIFICATION OF POLYMERS ACCORDING TO THERMAL PROCESSING BEHAVIOR

▪ THERMOPLASTICS ▪ THERMOSETS

CLASSIFICATION BASED ON PREPARATIVE TECHNIQUE

▪ BULK POLYMERIZATION ▪ SOLUTION POLYMERIZATION ▪ SUSPENSION POLYMERIZATION ▪ EMULSION POLYMERIZATION

BULK PROPERTIES OF POLYMERS

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

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

FUNCTIONALITY

under FUNCTIONALITY, a molecule may be classified ________________, ___________ and ____________ depending on whether it has one, two, or greater than two sites available for linking with other molecules.

monofunctional, bifunctional, or polyfunctional

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

✓Linear polymers

These long chains are flexible and may be thought of as a mass of “spaghetti.”

✓Linear polymers

Some of the common examples of linear polymers are

polyethylene, PVC, polystyrene, and polyamides.

_________ polymers are generally more rigid

linear

have side chains or branches growing out from the main chain

▪ BRANCHED POLYMERS

The side chains or branches are made of the _______________ as the main polymer chains.

same repeating units

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

one complete monomer unit

One of the most common example branched

low-density polyethylene (LDPE)

applications ranging from plastic bags, containers, textiles, and electrical insulation, to coatings for packaging materials

low-density polyethylene (LDPE) , branched polymers

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

crosslinked polymers

tend to be permanent in nature

Crosslinks

Once the crosslinks between the chains develop the polymer then becomes _______

thermoset.

✓Common examples include

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

Multifunctional monomers forming three or more active covalent bonds make three-dimensional networks

network polymers

These materials have distinctive mechanical and thermal properties

network polymers

network polymers

epoxies, polyurethanes, and phenol-formaldehyde

the material exhibits organized and tightly packed molecular chains

CRYSTALLINE

they have good strength & wear, and good chemical resistance, but they typically lack in impact resistance.

CRYSTALLINE

✓Examples of crystalline polymers include

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

polymers that have no crystalline regions and no uniformly packed molecules

Amorphous polymers

composed of amorphous regions where molecules are randomly arranged.

Amorphous polymers

good examples of amorphous polymers

✓Natural rubber latex and styrene-butadiene rubber (SBR)

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

degree of crystallinity

ranges from 0 to 100%, where 0% represents an amorphous material, and 100% represents a perfectly crystalline material.

degree of crystallinity

degree of crystallinity by ___________ may be determined from accurate density measurements, according to

weight , (image 25)

1, WATER BOTTLES, JARS, CAPS

PET (POLYETHYLENE TEREPHTHALATE)

2, SHAMPOO BOTTLES, GROCERY BAGS

HDPE (HIGH-DENSITY POLYETHYLENE)

3, CLEANING PRODUCTS, SHEETINGS

PVC (POLYVINYL CHLORIDE)

4, BREAD BAGS, PLASTIC FILMS

LDPE (LOW DENSITY POLYETHYLENE)

5, YOGURT CUPS, STRAWS, HANGER

POLYPROPYLENE

6, TAKE-AWAY AND HARD PACKAGING TOYS

POLYSTYRENE

7, BABY BOTTLES AND NYLON CDS

OTHERS

(IMAGE 33)

condensation polymerisation

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

homopolymer.

✓The purpose of homopolymers is to produce a polymer that has

increased mechanical properties. These enhanced mechanical properties include: tensile strength, stiffness, impact resistance, and short-term creep resistance.

increased mechanical properties enhanced

tensile strength, stiffness, impact resistance, and short-term creep resistance.

example of homopolymers

polyvinyl chloride polyethylene polypropylene, polycarbonate polyester nylon 6 nylon 11, polytetrafluoroethylene styrene

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

COPOLYMER

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

copolymerization.

The purpose of creating a copolymer is to manufacture a polymer with

more desirable properties

Copolymers typically experience a

lower crystallinity higher glass transition temperature improved solubility

to get Buna-S, copolymerization happened between

1,3-butadiene and Styrene

to get Nylon 6,6, copolymerization happened between

Hexamethylenediamine and Adipic acid

ABBABBBAABBAABAAABBA

two different mers by A and B, a random copolymer

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

alternating copolymer

-ABABABABABABABABABAB-

alternating copolymer

-AAAAAAAAAABBBBBBBBBB-

block copolymer

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

block copolymer

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

graft copolymer

(image 29)

graft copolymer

(image 29)

1. random 2. alternating 3. block 4. graft

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

✓Fibers

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

✓Fibers

Examples of fibers are

Polyester Nylon, Terelyne Spandex Kevlar Rayon Acetate Acrylic Lastex Polypropylene

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

elastomers

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

viscoelasticity.

polymers that have viscosity and elasticity

Elastomers

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

Elastomers

Examples of elastomers are

rubber polyurethanes polybutadiene

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

plastic

commonly used in commercially sold water bottles, soft drink bottles, sports drink bottles, and condiment bottles.

1 PET, Polyethylene terephthalate PET

commonly used in milk and juice bottles, detergent bottles. shampoo bottles, grocery bags, and cereal box iners.

2 PE-HD, Polyethylene (high density) HDPE

can be flexible or rigid is used for plumbing pipes, clear food packaging, shrink wrap, plastic children's toys, tablecloths, vinyl flooring, children's play mats, and blister packs (such as for medicines).

3 PVC, Polyvinyl chloride PVC

used for dry cleaning bags, bread bags, newspaper bags, produce bags, and garbage bags, as well as "paper" milk cartons and hot/cold beverage cups.

04 PE-LD, Polyethylene (low density) LDPE

used to make yogurt containers, deli food containers, furniture, luggage and winter clothing insulation.

05 PP Polypropylene

also popularly known as Styrofoam, is used for cups, plates, take-out containers, supermarket meat trays, and packing peanuts.

06 PS Polystyrene

Any plastic item not made from the above six plastics is lumped together HERE things like CD's baby bottles and headlight lens

07 O Bisphenol A and others

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

CONDENSATION POLYMERS, condensation

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

CONDENSATION POLYMERS

releasing by-products in CONDENSATION POLYMERS.

water or methanol molecule

The by-products are normally referred to as

condensate.

✓ This reaction can occur between any two growing polymer molecules

CONDENSATION POLYMERS

✓ This reaction can occur between any two growing polymer molecules and can be represented by

(image 33)

Several synthetic condensation polymers include

nylon kevlar polyester Bakelite, Melamine polycarbonates polyurethanes epoxies

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

Addition polymers

✓Examples of addition polymers are

polystyrene polyethylene, polyacrylonitrile polymethyl methacrylate polyvinyl chloride

if n is added in an ethene, it would result in a

polyethene (image 34)

The addition polymerization can be schematically represented as follows

(image 34)

✓Plastics that soften when heated and become firm again when cooled

THERMOPLASTICS

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

thermoplastic

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

thermoplastic

✓Examples of common thermoplastic polymers include

polyethylene polystyrene poly(ethylene terephthalate) poly(vinyl chloride) polypropylene, polycarbonate nylon Teflon

These are plastics that soften when heated and can be molded but harden permanently.

THERMOSETS

They will decompose when reheated.

THERMOSETS

✓ A thermoset when heated, undergoes a chemical change to produce a

cross-linked, solid polymer. cross-linked, solid polymer.

Thermosets usually exist initially as liquids called

prepolymers

they can be shaped into desired forms by the application of heat and pressure but are incapable of undergoing repeated cycles of softening and hardening.

prepolymers of thermosets

Principal examples of thermosets include

epoxy phenolformaldehyde resins unsaturated polyesters.

✓ Another example of thermosets

Bakelite

used in toasters, handles for pots and pans, dishes, electrical outlets and billiard ba

Bakelite

differences (image 37)

1. thermoplastic 2. thermosets

draw the graph showing differences between thermoplastics and thermoset

(image 37)

a polymer that is irreversibly hardened by heat

thermoset

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

▪ BULK POLYMERIZATION

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

polymer product

(image 38)

bulk polymerization

Example of polymers that can be produced by bulk polymerization are

polyvinyl chloride (PVC) polyethylene (PE) Polypropylene (PP) Polyethylene terephthalate (PET) Polystyrene (PS), Polyvinylidene chloride (PVDC) Polytetrafluoroethylene (PTFE).

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

✓Solution polymerization

Reactant and product in Solution polymerization

monomer (reactant) and polymer (product)

usage of ✓Solution polymerization in the industry

production of polyacrylonitrile polyacrylic acid polyacrylamide polyvinyl alcohol polybutadiene

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.

Suspension polymerization

✓Several commercially important ______________ are manufactured using suspension polymerization

vinyl copolymers

Example of commercially important vinyl copolymers which are manufactured using suspension polymerization

polystyrene (general purpose, expandable and high impact) polymethyl methacrylate polyvinyl acetate styrene–acrylonitrile (SAN) copolymers acrylonitrile–butadiene–styrene (ABS) copolymers polyvinyl chloride (PVC).

(image 40)

suspension polymerization

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.

EMULSION POLYMERIZATION

in EMULSION POLYMERIZATION, where the initiator is located

aqueous phase (continuous phase)

example of emulsion polymerization is used for the commercial manufacture of many important polymers including polyvinyl chloride (PVC)

polymethyl methacrylate polystyrene

quantifies how much stress the material will endure before failing

tensile strength of a material

Tensile strength increases with

polymer chain length

quantifies the elasticity of the polymer

✓ Young's Modulus

ratio of the rate of change of stress to strain.

✓ Young's Modulus

relate to how rapidly molecules move through the polymer matrix

▪ TRANSPORT PROPERTIES

example of ▪ TRANSPORT PROPERTIES

diffusivity

important in many applications of polymers for films and membranes.

▪ TRANSPORT PROPERTIES

a transition from a crystalline or semi-crystalline phase to a solid amorphous phase NOT a solid-liquid phase transition

➢MELTING POINT

a crucial physical parameter for polymer manufacturing, processing, and use

glass-transition temperature (Tg)

✓ Below Tg

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

Above Tg

molecular motions are activated, and polymers are rubbery and viscous