P - PowerPoint PPT Presentation

Loading...

PPT – P PowerPoint presentation | free to view - id: 46d258-YjAyM



Loading


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation
Title:

P

Description:

... elasticity to natural rubber inferior to chloroprene rubber in weathering resistance more expensive than natural rubber and styrene butadiene ... – PowerPoint PPT presentation

Number of Views:824
Avg rating:3.0/5.0
Slides: 189
Provided by: chaine
Category:
Tags: natural | rubber

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: P


1
P
L
M
R
E
Y
O
S
IE 21 - TFU DIMAANO, JOYCE ANNE PATAG,
CELINE PEREIRA, NOREEN ANNE SUANSING, ANNE
BERNADETTE
2
POLYMERS THEYRE EVERYWHERE!
STYROFOAM CUPS (POLYSTYRENE) PAINT (ACRYLICS)
MOLECULES (POLYETHYLENE) DOLLHOUSE EXTERIOR
(POLYVINYL CHLORIDE)
3
POLYMERS
  • Made up of macromolecules,
  • have high molar masses and
  • are composed of a large
  • number of repeating units

4
POLYMERS
(GENERAL PROPERTIES)
lightweight low strength and stiffness corrosion
resistance high electrical resistance low thermal
conductivity good resistance to chemicals high
coefficient of expansion good optical properties
(opaque, transparent, colors) high
formability low cost (compared to metals) low
energy content not as dimensionally stable as
metals
5
polymerization
gtgt Chemical reaction by which monomers are
linked to form larger molecules
gtgt Two types A. Condensation B. Addition
6
condensation polymerization
gtgt Reaction by products such as water are
condensed out gtgt Also called step-reaction
polymerization because polymer
molecules grows step by step
7
addition polymerization
gtgt Also known as chain-reaction
polymerization gtgt Bonding takes place without
reaction by- products gtgt Called chain
reaction because of the high rate at
which long molecules form simultaneously
8
some definitions
gtgt monomers used in the synthesis of the
large molecule gtgt
Molecular Weight ? higher molecular weight,
greater chain length gtgt degree of
polymerization ? Ratio of molecular weight
of polymer to the molecular
weight of monomer
9
bonding
gtgt Monomers are linked by covalent bonds
(primary bonds), forming a polymer chain gtgt
Polymer chains are held together by
secondary bonds, such as van der Waals
bonds, hydrogen bonds, and ionic bonds. gtgt The
longer the polymer chain, the greater is
the energy needed to overcome the secondary
bond strength
10
Linear polymers
gtgt Chain like polymers are called linear
polymers because of their linear structure.
A linear polymer may contain some branched
and cross-linked chains. As result of
branching and cross-linking, the polymers
properties can change.
11
branching
gtgt Side-branched chains are attached to the
main chain during the synthesis of the
polymer gtgt Branching interferes with the
relative movement of the molecule chains.
Resistance to deformation and stress-
cracking are affected.
12
cross-linking
gtgt Have adjacent chains linked by covalent
bonds gtgt Polymers with cross-linked chain
structures are called thermosetting plastics
(thermosets) gtgt Cross linking influence
hardness, strength, brittleness, and better
dimensional stability, vulcanization of
rubber
13
networks
Are highly cross-linked
14
MECHANICAL PROPERTIES OF POLYMERS
gtgt deformation is very dependent on time gtgt
deformation is dependent on temperature ? as
temperature increases, the weak van
der waals forces are further diminished,
and slip occurs more easily between
adjacent chains
15
MECHANICAL PROPERTIES OF POLYMERS
gtgt with the application of stress when two
atoms within a chain are held by strong
covalent bonds, displacement of the atoms
relative to each other occurs
instantaneously on the application of
stress gtgt stress is removed atoms
immediately return to their original
positions
16
MECHANICAL PROPERTIES OF POLYMERS
gtgt tensile properties are highly dependent on
temperature. rigid polymers elongation
increases with
an increase in temperature rubbers
elongation increases with a
decrease in temperature
17
STRESS - STRAIN DIAGRAMS
Soft and weak
Hard and brittle
Hard and strong
Soft and tough
Hard and tough
Ideal elastomer
18
MECHANICAL PROPERTIES OF POLYMERS
gtgt creep dependent on temperature ?
below tg, increase in temperature
creep rate increases, elongation
increases ? At tg, increase in
temperature gives much greater
elongation than in lower
temperatures ? above tg, increase in
temperature great increase in
elongation, creep rate decreases
19
POLYMERS
(TYPES)
THERMOPLASTICS
THERMOSETS
ELASTOMERS
ADDITIVES
BIODEGRADABLE PLASTICS
20
thermoplastics
gtgt most commonly used polymer gtgt high molecular
weight polymers whose chains associate
through weak van der waals forces gtgt can go
through melting or freezing cycles
repeatedly gtgt can be softened repeatedly by the
application of heat gtgt they melt to a
liquid and freezes to a brittle, glassy
state when cooled sufficiently
21
Effect of temperature
Temperature above Tg (glass transition temperature) thermoplastic becomes leathery increasing the temperature more it becomes rubbery
Temperature above Tm (melting point) becomes a viscous fluid viscosity decreases with increasing temperature like ice cream can be softened, molded and refrozen several times repeated heating and cooling causes degradation or thermal aging
Effect on strength and elastic modulus At higher temperature strength and elastic modulus decrease
22
Effect of rate of deformation
gtgt can undergo large uniform deformations in
tension before they fracture gtgt allows
thermoforming into complex shapes, such as
bottles of soft drinks
23
orientation
gtgt When thermoplastics are deformed (e.g.
stretching) long chain molecules tend to
align in the general direction of elongation.
This strengthens the polymer in this direction
but weakens in the traverse direction. gtgt
Anisotropic the specimen becomes stronger
and stiffer in the elongated direction than in
its traverse direction
24
crazing
gtgt When subject to tensile stresses or bending
the polymer develops localized, wedged-
shaped, narrow regions of high of highly
deformed material. gtgt Appears like cracks. gtgt
Spongy material with 50 voids gtgt When further
tensile strength is applied, the voids
causes the polymer to fracture gtgt Typically
observed in transparent glassy polymers gtgt
Enhanced by ? Environment the presence of
solvents,
lubricants or water vapor ? Residual
stress ? Radiation
25
Stress whitening
gtgt when subject to tensile stresses (e.g.
bending) the plastic becomes lighter in color
due to the voids formed. gtgt Material becomes
less translucent or more opaque
Example White line formed when a plastic
folder is bent
26
Water absorption
gtgt Water acts as a plasticizing agent --
makes the polymer more plastic gtgt Lubricates the
chains in the amorphous region gtgt Lowers
the glass-transition temperature, yield
stress and elastic modulus gtgt Also changes the
dimensions of the polymer especially in a
humid environment
27
Thermal and electrical properties
gtgt Low electrical conductivity ? Used for
insulators and packaging material for
electronic components ? Doping to
increase the
electrical conductivity
by introducing
impurities e.g. metal
powder ?Increases with water
absorption gtgt Low specific gravity gtgt High
coefficient of thermal expansion
28
Creep and stress relaxation
gtgt Susceptible to creep and stress
relaxation at room temperature
29
thermoplastics
acetals
polyesters
acrylics
polyethylenes
abs
polyimides
cellulosics
polypropylenes
fluorocarbons
polystyrenes
polyamides
polysulfones
polycarbonates
Polyvinyl chloride
30
ACETALS
gtgt ACETIC AND ALCOHOL gtgt COMMON TRADE NAME
DELRIN gtgt VERY GOOD STRENGTH AND STIFFNESS gtgt ARE
CREEP RESISTANT gtgt GOOD FATIGUE ENDURANCE gtgt HIGH
CRYSTALLINITY AND HIGH MELTING POINT MAKE
IT SUITABLE FOR REPLACING SOME METALS gtgt HAVE
GOOD RESISTANCE TO ABRASION, MOISTURE, HEAT
AND CHEMICALS gtgt GOOD ELECTRICAL PROPERTIES
gtgt HAVE LOW FRICTION gtgt SLIGHT WATER
ABSORPTION gtgt PROVEN RESISTANT TO PESTICIDAL
CHEMICALS
31
DESIGN CONSIDERATIONS -- acetals
gtgt affected by prolonged exposure to UV light
(not good for outdoor use) gtgt cannot be
used for applications involving high
stress or power frequencies at temperatures
above 70oc gtgt difficult to join to self and
other materials
32
ACETALS ( APPLICATIONS )
  1. IMPELLORS AND OTHER PARTS FOR WATER PUMPS,
    WASHING MACHINES, AND EXTRACTOR FANS
  2. HINGES AND WINDOW CATCHES
  3. SHOWER HEADS
  4. INSTRUMENT PANELS AND HOUSINGS FOR AUTOMOBILES

(A)
(C)
33
thermoplastics
acetals
polyesters
acrylics
polyethylenes
abs
polyimides
cellulosics
polypropylenes
fluorocarbons
polystyrenes
polyamides
polysulfones
polycarbonates
Polyvinyl chloride
34
ACRYLICS
gtgt POLYMETHYL METHACRYLATE (PMMA) gtgt COMMON TRADE
NAME PLEXIGLAS AND LUCRITE gtgt HAVE MODERATE
STRENGTH gtgt GOOD OPTICAL PROPERTIES HAVE HIGHEST
OPTICAL CLARITY, TRANSMITTING OVER 90
LIGHT gtgt TRANSPARENT, BUT CAN BE MADE OPAQUE gtgt
AVAILABLE IN A WIDE RANGE OF COLORS gtgt GENERALLY
RESISTANT TO CHEMICALS gtgt GOOD ELECTRICAL AND
WEATHER RESISTANCE gtgt HIGH TENSILE AND
DIALECTRIC STRENGTHS gtgt GOOD LOW
TEMPERATURE CHARACTERISTICS
35
DESIGN CONSIDERATIONS -- acrylics
gtgt poor fatigue resistance gtgt low scratch
resistance compared to glass gtgt higher cost than
rigid transparent pvc and polystyrene gtgt
low continuous use temperature (approx. 50oc)
36
ACRYLICS ( APPLICATIONS )
  1. FIBER OPTICS
  2. AUTOMOTIVE REAR LIGHT LENSES
  3. SIGNS
  4. LIGHTING FITTINGS
  5. MOTORCYCLE WINDSCREENS
  6. WINDSHIELDS

(A)
(F)
(E)
(C)
37
thermoplastics
acetals
polyesters
acrylics
polyethylenes
abs
polyimides
cellulosics
polypropylenes
fluorocarbons
polystyrenes
polyamides
polysulfones
polycarbonates
Polyvinyl chloride
38
ABS
gtgt ACRONYM MEANS ACRYLONITRILE-BUTADIENE-
STYRENE gtgt ARE DIMENSIONALLY STABLE AND
RIGID gtgt HAVE HIGH IMPACT VALUE ALONG WITH HIGH
STRENGTH (RESISTS IMPACT BY FLYING STONES) gtgt
ARE FLAMMABLE gtgt HAVE LOW WEIGHT gtgt HAVE GOOD
HEAT, WEATHER, ABRASION, ELECTRICAL AND
CHEMICAL RESISTANCE gtgt GOOD STRENGTH AND
TOUGHNESS EVEN AT SUB- ZERO
TEMPERATURES gtgt RESISTS ATTACK BY
ACIDS
39
ABS ( APPLICATIONS )
  1. PIPES
  2. PROTECTIVE HELMETS
  3. INSTRUMENTS AND APPLIANCE HOUSINGS
  4. REFRIGERATOR PARTS
  5. BATTERY CASES
  6. WATER PUMPS
  7. TELEPHONE CASINGS
  8. LUGGAGE CASES

(G)
(B)
(H)
40
thermoplastics
acetals
polyesters
acrylics
polyethylenes
abs
polyimides
cellulosics
polypropylenes
fluorocarbons
polystyrenes
polyamides
polysulfones
polycarbonates
Polyvinyl chloride
41
CELLULOSICS
gtgt MADE FROM NATURALLY OCCURRING MATERIALS,
SUCH AS COTTON gtgt HAVE VERY GOOD OPTICAL
PROPERTIES gtgt GOOD RESISTANCE TO OUTDOOR
WEATHERING gtgt ARE RIGID, STRONG AND TOUGH gtgt HAVE
HIGH WATER ABSORPTION RATES gtgt ARE AFFECTED BY
HEAT AND CHEMICALS
42
DESIGN CONSIDERATIONS cellulosics
gtgt optical properties are inferior to
acrylics gtgt high electrical dissipation (power)
factor gtgt tendency to creep under load gtgt
staining can occur on contact with some other
plastics gtgt all types will burn slowly,
though self- extinguishing grades are
available gtgt permeable to water vapor and gases
in various degrees
43
CELLULOSICS ( APPLICATIONS )
  1. KNOBS
  2. SAFETY GOGGLES
  3. STEERING WHEELS
  4. LIGHT FIXTURES
  5. FRAMES FOR EYEGLASSES
  6. BILLIARD BALLS

(C)
(F)
(E)
(B)
44
thermoplastics
acetals
polyesters
acrylics
polyethylenes
abs
polyimides
cellulosics
polypropylenes
fluorocarbons
polystyrenes
polyamides
polysulfones
polycarbonates
Polyvinyl chloride
45
FLUOROCARBONS
gtgt COMMON TRADE NAME TEFLON gtgt HAVE LOW
FRICTION gtgt HAVE NON-ADHESIVE PROPERTIES gtgt HAVE
GOOD RESISTANCE TO TEMPERATURE, CHEMICALS,
WEATHER AND ELECTRICITY gtgt DO NOT DEGRADE IN UV
LIGHT AND ARE NOT ATTACKED BY FUNGI OR
BACTERIA gtgt SELF-EXTINGUISHING gtgt STABLE AT HIGH
TEMPERATURES (UP TO 260OC CONTINUOUS
EXPOSURE)
46
DESIGN CONSIDERATIONS fluorocarbons
gtgt expensive gtgt stiffer at low temperatures, but
not brittle gtgt not good for high loading and
elevated temperatures gtgt toxic products
upon decomposition gtgt have very high thermal
expansion difficult to machine
47
FLUOROCARBONS ( APPLICATIONS )
  1. NONSTICK COATINGS FOR COOKWARE
  2. ELECTRICAL INSULATION FOR HIGH-TEMPERATURE WIRE
    AND CABLE
  3. GASKETS
  4. ANTI-ADHESIVE AND ANTI-ICING COATINGS

(A)
(C)
48
thermoplastics
acetals
polyesters
acrylics
polyethylenes
abs
polyimides
cellulosics
polypropylenes
fluorocarbons
polystyrenes
polyamides
polysulfones
polycarbonates
Polyvinyl chloride
49
POLYAMIDES
gtgt FROM POLY, AMINE, AND CARBOXYL ACID gtgt
COMMON TRADE NAME KEVLAR gtgt TWO MAIN
TYPES A. NYLON B. ARAMIDS
50
POLYAMIDES ? NYLONS
gtgt HAVE GOOD STRENGTH AND TOUGHNESS gtgt
FLEXIBLE gtgt RESISTANT TO ABRASION gtgt
SELF-LUBRICATING gtgt LOW COEFFICIENT OF
FRICTION gtgt RESISTANT TO MOST CHEMICALS gtgt ARE
HYGROSCOPIC (ABSORB WATER), BUT RESULTS
IN THE REDUCTION OF MECHANICAL PROPERTIES
AND INCREASES PART DIMENSIONS gtgt HAVE GOOD
RESISTANCE MOST COMMON SOLVENTS
gtgt DETERIORATES WHEN EXPOSED TO UV LIGHT
51
DESIGN CONSIDERATIONS nylons
gtgt all nylons absorb or give up moisture to
achieve equilibrium with ambient conditions gtgt
good commercial insulators but electrical
properties are greatly influenced by moisture
content and/or temperature increase
52
NYLON ( APPLICATIONS )
  1. GEARS
  2. VALVES
  3. ELECTRICAL EQUIPMENT
  4. HANDLES AND KNOBS
  5. SHOCK ABSORBERS
  6. SURGICAL AND PHARMACEUTICAL PACKAGING
  7. RAINCOATS
  8. ZIPPERS

(H)
(G)
(D)
53
POLYAMIDES ? ARAMIDS
gtgt AROMATIC POLYAMIDES gtgt VERY HIGH TENSILE
STRENGTH AND STIFFNESS
54
ARAMIDS ( APPLICATIONS )
  1. BULLETPROOF VESTS
  2. RADIAL TIRES
  3. CABLES

(B)
(A)
55
thermoplastics
acetals
polyesters
acrylics
polyethylenes
abs
polyimides
cellulosics
polypropylenes
fluorocarbons
polystyrenes
polyamides
polysulfones
polycarbonates
Polyvinyl chloride
56
POLYCARBONATES
gtgt COMMON TRADE NAME LEXAN gtgt DUCTILE,
NONFLAMMABLE, SELF-EXTINGUISHING gtgt HAVE GOOD
ELECTRICAL PROPERTIES gtgt HIGH STRENGTH AND
OUTSTANDING TOUGHNESS EVEN AT SUB-ZERO
TEMPERATURES gtgt GOOD CREEP RESISTANCE gtgt HIGH
IMPACT AND HEAT RESISTANCE gtgt RESISTANT TO OILS
AND WEAK ACIDS
57
DESIGN CONSIDERATIONS polycarbonates
gtgt low scratch resistance gtgt selection of
adhesives and paints must be undertaken
with care owing to poor solvent
resistance gtgt although polycarbonate can be
repeatedly cleaned in hot water, unlimited
long term exposure to hot water above 60oc
is not advised
58
POLYCARBONATES ( APPLICATIONS )
  1. AIRCRAFT PARTS
  2. SAFETY HELMETS
  3. OPTICAL LENSES
  4. BULLET-RESISTANT WINDOW GLAZING
  5. MEDICAL APPARATUS
  6. WINDSHIELDS
  7. BOTTLES
  8. FOOD-PROCESSING EQUIPMENT

(E)
(G)
59
thermoplastics
acetals
polyesters
acrylics
polyethylenes
abs
polyimides
cellulosics
polypropylenes
fluorocarbons
polystyrenes
polyamides
polysulfones
polycarbonates
Polyvinyl chloride
60
POLYESTERS
gtgt COMMON TRADE NAMES DACRON, MYLAR, AND
KODEL gtgt STRONG AND STABLE gtgt GOOD CREEP AND
FATIGUE RESISTANCE gtgt GOOD WEAR AND ABRASION
RESISTANCE gtgt LOW FRICTION gtgt GOOD HEAT
RESISTANCE gtgt EXCELLENT ELECTRICAL INSULATION gtgt
LOW WATER ABSORPTION gtgt RETAINS COLOR EVEN AT
HIGH TEMPERATURES
61
DESIGN CONSIDERATIONS polyesters
gtgt ATTACKED BY STRONG ACIDS AND ALKALIS gtgt
PROLONGED USE IN WATER OR AQUEOUS SOLUTIONS
ABOVE 70OC NOT RECOMMENDED gtgt EXPENSIVE ON RAW
MATERIAL COSTS BUT CAN BE OFFSET BY
PROCESSING ADVANTAGES AGAINST COMPETITIVE
MATERIALS
62
POLYESTERS ( APPLICATIONS )
  1. TEXTILE FIBER
  2. DRUMS AND LOUDSPEAKER CONES
  3. RECORDING MATERIALS
  4. BOOK COVERING
  5. PHOTOGRAPHIC FILMS

(B)
63
thermoplastics
acetals
polyesters
acrylics
polyethylenes
abs
polyimides
cellulosics
polypropylenes
fluorocarbons
polystyrenes
polyamides
polysulfones
polycarbonates
Polyvinyl chloride
64
POLYETHYLENES
gtgt ONE OF THE MOST VERSATILE THERMOPLASTICS gtgt
INEXPENSIVE gtgt LOW WATER ABSORPTION gtgt RESISTANT
TO MOST INORGANIC ACIDS AND ALKALIS AT ROOM
TEMPERATURES gtgt NON-TOXIC gtgt TOUGH AND FLEXIBLE,
OVER A WIDE TEMPERATURE RANGE gtgt ARE
DIMENSIONALLY STABLE AND ARE EASILY MOLDED
65
POLYETHYLENES
  • gtgt GOOD RESISTANCE TO MOST SOLVENTS
  • POLYETHYLENE CAN BE DISSOLVED AT HIGH
    TEMPERATURES IN AROMATIC HYDROCARBONS (LIKE
    TOLUENE AND XYLENE) OR CHLORINATED SOLVENTS (LIKE
    TRICHLOROETHANE AND TRICHLOROBENZENE)
  • gtgt HAVE GOOD WEATHERING PROPERTIES, BUT MAY
    DETERIORATE WHEN EXPOSED TO LIGHT FOR A LONG
    PERIOD OF TIME
  • TWO FACTORS
  • MOLECULAR WEIGHT
  • NUMBER OF SIDE CHAINS EXISTING ON MAINLY
    LINEAR MOLECULES

66
POLYETHYLENES
gtgt THREE MAJOR CLASSES A. LOW DENSITY
(LDPE) B. HIGH DENSITY (HDPE) C.
ULTRA-HIGH MOLECULAR WEIGHT (UHMWPE)
67
LDPE VERSUS HDPE
Low density polyethylene (LDPE)
Tough at much lower temperature (embrittles at 60?C). Translucent. Flexible. Upper service temperature limit of 88?C. Lower warpage. Improved environmental stress crack resistance. Improved heat resistance. Improved toughness, puncture resistance and tear strength in films.
High density polyethylene (HDPE)
Better chemical resistance. Better creep resistance. Five times stiffness of LDPE at room temperature. Higher temperature service (up to 130?C). Can withstand hot water sterilization but not steam.
68
DESIGN CONSIDERATIONS polyethylenes
gtgt resistant to most acids and alkalis attacked
by highly oxidizing acids such as
concentrated nitric, glacial acetic, fuming
sulfuric and hydrogen peroxide gtgt
insoluble in most organic solvents below 60oc
but some absorption, softening or
embrittlement may occur in alcohol, esters,
amines and phenols
69
POLYETHYLENES (APPLICATIONS)
  1. BOTTLES
  2. GARBAGE CANS
  3. LUGGAGE
  4. TOYS
  5. PACKAGING MATERIALS

(B)
(D)
70
POLYETHYLENES (UHMWPE) (APPLICATIONS)
PARTS REQUIRING HIGH IMPACT TOUGHNESS AND
ABRASIVE WEAR RESISTANCE
71
thermoplastics
acetals
polyesters
acrylics
polyethylenes
abs
polyimides
cellulosics
polypropylenes
fluorocarbons
polystyrenes
polyamides
polysulfones
polycarbonates
Polyvinyl chloride
72
POLYIMIDES
gtgt HAVE THE STRUCTURE OF THERMOPLASTICS BUT
THE NON-MELTING CHARACTERISTIC OF
THERMOSETS gtgt HAVE EXCELLENT ELECTRICAL
INSULATION gtgt FLAME AND HEAT RESISTANT gtgt HAVE
VERY GOOD ABRASION RESISTANCE gtgt RESISTANT TO
DEGRADATION BY OXIDATION AND TO MOST
CHEMICALS, EXCEPT FOR STRONG BASES
73
thermoplastics
acetals
polyesters
acrylics
polyethylenes
abs
polyimides
cellulosics
polypropylenes
fluorocarbons
polystyrenes
polyamides
polysulfones
polycarbonates
Polyvinyl chloride
74
POLYPROPYLENES
gtgt SIMILAR PROPERTIES TO POLYETHYLENE BUT HAVE
BETTER HEAT RESISTANCE gtgt CAN BE STERILIZED gtgt
HAVE EXCELLENT RESISTANCE TO CHEMICAL
ATTACK BY ACIDS, ALKALIS, AND SALTS EVEN AT
ELEVATED TEMPERATURES gtgt TOUGH, RIGID AND
LIGHTWEIGHT gtgt HAVE GOOD RESISTANCE TO TEARING
AND FATIGUE ? MOST PLASTIC LIVING HINGES,
(FOR EXAMPLE FLIP-TOP BOTTLES) ARE
MADE OF THIS MATERIAL
75
POLYPROPYLENES
gtgt HAVE GOOD MECHANICAL PROPERTIES gtgt MOST
COMMERCIAL POLYPROPYLENE HAS A LEVEL OF
CRYSTALLINITY INTERMEDIATE BETWEEN THAT OF LDPE
ANG HDPE. gtgt HAVE INTERMEDIATE YOUNG MODULUS gtgt
ARE LESS TOUGH THAN LDPE, AND ARE LESS BRITTLE
THAN HDPE gtgt CAN BE USED AS REPLACEMENT FOR
ENGINEERING PLASTICS LIKE ABS. gtgt VERY THIN
SHEETS CAN BE USED AS DIELECTRIC WITHIN CERTAIN
HIGH PERFORMANCE PULSE AND LOW LOSS RF CAPACITORS
76
DESIGN CONSIDERATIONS polypropylenes
gtgt attacked by highly oxidizing acids such as
fuming sulfuric, liquid and gaseous halogens
and swells rapidly in chlorinated
solvents and aromatics gtgt joined more easily to
other materials (example wood and
aluminum) than to itself gtgt more expensive than
polyethylene
77
POLYPROPYLENES ( APPLICATIONS )
  1. HOSPITAL AND LABORATORY EQUIPMENT
  2. SHEETS USED IN PACKAGING
  3. MONOFILAMENTS USED AS ROPES AND FISHING NETS

(A)
(C)
78
thermoplastics
acetals
polyesters
acrylics
polyethylenes
abs
polyimides
cellulosics
polypropylenes
fluorocarbons
polystyrenes
polyamides
polysulfones
polycarbonates
Polyvinyl chloride
79
POLYSTYRENES
gtgt COMMON TRADE NAME STYROPOR gtgt INEXPENSIVE gtgt
TOUGH AND DENSE gtgt HARD AND RIGID gtgt INCLINED TO
BE BRITTLE BECAUSE OF HIGH Tg gtgt LOW WATER
ABSORPTION gtgt GOOD ELECTRICAL PROPERTIES HIGH
DIALECTRIC STRENGTH, HIGH ELECTRICAL
CONDUCTIVITY) gtgt GOOD DIMENSIONAL STABILITY gtgt
CLEAR AND TRANSPARENT gtgt HAVE EXCELLENT
DIALECTRIC STRENGTHS
80
DESIGN CONSIDERATIONS polystyrenes
gtgt brittle, unless modified gtgt tendency to
stress-cracking gtgt low elevated temperature
strength gtgt degraded by uv radiation gtgt high
impact materials are not usually transparent
81
POLYSTYRENES ( APPLICATIONS )
  1. CASSETTES AND REELS
  2. VENDING CUPS AND FOOD TRAYS
  3. PIPES
  4. CEILING TILES (RIGID FOAMS USED IN BUILDING AND
    REFRIGERATION AS INSULATION AGAINST HEAT AND
    SOUND)

(C)
(A)
(B)
82
thermoplastics
acetals
polyesters
acrylics
polyethylenes
abs
polyimides
cellulosics
polypropylenes
fluorocarbons
polystyrenes
polyamides
polysulfones
polycarbonates
Polyvinyl chloride
83
POLYSULFONES
gtgt HAVE EXCELLENT STRENGTH AND CREEP
RESISTANCE gtgt HAVE EXCELLENT RESISTANCE TO HEAT,
WATER AND STEAM gtgt RESISTANT TO BURNING gtgt
RESISTANT TO CHEMICALS gtgt CAN BE REPEATEDLY
STERILIZED gtgt CAN BE USED IN ELECTRONIC
APPLICATIONS
84
DESIGN CONSIDERATIONS polysulfones
gtgt not recommended for outdoor service unless
painted or plated lower resistance to uv light
than polycarbonates gtgt upper service
temperature limit of 170oc gtgt tensile strength
drops sharply above 170oc
85
POLYSULFONES ( APPLICATIONS )
  1. PRINTED CIRCUIT BOARDS (HEAT RESISTANT TO
    SOLDERING)
  2. HAIR DRIERS
  3. MICROWAVE OVEN PARTS AND COOKWARE
  4. COFFEE MACHINES
  5. TV COMPONENTS
  6. MEDICAL AND FOOD REQUIREMENTS INVOLVING REPEATED
    STERILIZATION

(B)
(A)
(D)
86
thermoplastics
acetals
polyesters
acrylics
polyethylenes
abs
polyimides
cellulosics
polypropylenes
fluorocarbons
polystyrenes
polyamides
polysulfones
polycarbonates
polyvinyl chloride
87
POLYVINYL CHLORIDE
gtgt INEXPENSIVE gtgt UNPLASTICISED FORM IT IS TOUGH
AND HARD gtgt PLASTICISED SOFT, FLEXIBLE AND
RUBBERY gtgt HAS GOOD DIMENSIONAL STABILITY gtgt GOOD
RESISTANCE TO WATER, ACIDS, ALKALIS, AND MOST
COMMON SOLVENTS gtgt HAS TWO TYPES -- RIGID PVC
-- FLEXIBLE PVC
88
POLYVINYL CHLORIDE (RIGID)
gtgt COST-SAVING gtgt TOUGH AND HARD, BUT LIGHT gtgt
LOWER COEFFICIENT OF FRICTION AND BETTER ABRASIVE
WEAR RESISTANCE THAN FLEXIBLE GRADES gtgt LOWER
COEFFICIENT OF THERMAL EXPANSION gtgt CAN BE
GLASS-FIBER REINFORCED TO IMPROVE STRENGTH AND
STIFFNESS gtgt HAS CHEMICAL AND CORROSION
RESISTANCE gtgt NON-FLAMMABILITY
89
POLYVINYL CHLORIDE (FLEXIBLE)
gtgt COST-SAVING gtgt WIDE RANGE OF FLEXIBILITY
POSSIBLE gtgt HAS REPLACED RUBBER AND OTHER
ELASTOMERS IN A VARIETY OF APPLICATIONS gtgt
NON-FLAMMABILITY gtgt HAS RESISTANCE TO ABRASION,
MOISTURE AND CHEMICALS
90
DESIGN CONSIDERATIONS rigid pvc
gtgt NOT SUITABLE FOR APPLICATIONS REQUIRING
HEAT RESISTANCE AND STRENGTH gtgt ATTACKED BY
STRONG ACIDS
91
DESIGN CONSIDERATIONS flexible pvc
gtgt CREEP PROPERTIES ARE INFERIOR TO RIGID
PVC gtgt MORE SUSCEPTIBLE TO STAINING, CHEMICAL
AND MICROBIOLOGICAL ATTACK
92
RIGID POLYVINYL CHLORIDE ( APPLICATIONS )
  1. PIPES, RAIN WATER SYSTEMS AND GUTTERING
  2. WINDOW FRAMES
  3. TERMINAL BOXES
  4. BLOWN BOTTLES AND CONTAINERS FOR OIL, WINE,
    BEVERAGES, SHAMPOOS AND CERTAIN COSMETICS

(C)
(D)
93
FLEXIBLE POLYVINYL CHLORIDE ( APPLICATIONS )
  1. FOLDING DOORS
  2. TARPAULINS
  3. CLING WRAP
  4. FOOTWEAR
  5. IMITATION OF LEATHER FOR CLOTHING, UPHOLSTERY AND
    TRAVEL GOODS
  6. BATTERY SEPARATORS

(A)
(C)
(E)
(B)
94
thermosets
gtgt short term for thermosetting
plastics gtgt during polymerization, the shape
of the part is permanently set
(network is completed)
95
thermosets
gtgt cannot be softened by re-heating gtgt curing
is irreversible gtgt due to the formation of
covalent bonds between chain molecules
96
thermosets
(POLYMERIZATION PROCESS)
STAGE 1 CHEMICAL PLANT MOLECULES ARE PARTIALLY
POLYMERIZED INTO LINEAR CHAINS
STAGE 2 PARTS PRODUCING PLANT CROSS LINKING
IS COMPLETED UNDER HEAT AND PRESSURE DURING THE
MOLDING AND THE SHAPING OF THE PART
97
thermosets
(VERSUS THERMOPLASTICS)
gtgt temperature and rate of deformation does
not affect strength and hardness gtgt have better
mechanical, thermal, and chemical
properties gtgt have better electrical resistance
and dimensional stability
98
thermosets
(AT SUFFICIENTLY HIGH TEMPERATURES)
THEY BURN UP, DEGRADE AND CHAR.
99
thermosets
alkyds
phenolics
aminos
polyesters
urea
polyimides
epoxies
silicones
100
ALKYDS
gtgt FROM ALKYL (ALCOHOL) AND ACID gtgt HAVE
GOOD ELECTRICAL INSULATING PROPERTIES gtgt HAVE
GOOD IMPACT RESISTANCE gtgt GOOD DIMENSIONAL
STABILITY gtgt HAVE LOW WATER ABSORPTION gtgt
FUNGUS-RESISTANT gtgt VERY GOOD DIELECTRIC
PROPERTIES (ACCOUNTS FOR THE HIGH COST OF
ELECTRICAL AND ELECTRONIC COMPONENTS)
gtgt GOOD COLOR STABILITY
101
DESIGN CONSIDERATIONS -- alkyds
gtgt APPLICATIONS CONFINED TO ELECTRICAL OR
DECORATIVE PRODUCTS gtgt ATTACKED BY ALKALIS AND
STRONG ACIDS gtgt ELECTRICAL PROPERTIES ARE NOT
MAINTAINED UNDER SEVERELY HUMID
CONDITIONS gtgt RESTRICTED COLOR POSSIBILITIES gtgt
MORE EXPENSIVE AND TOUGHER THAN PHENOLICS
102
ALKYDS ( APPLICATIONS )
  1. MICROWAVE OVEN COOKWARE
  2. AUTOMOTIVE DISTRIBUTOR CAPS AND ROTORS
  3. SWITCH GEAR
  4. CIRCUIT BREAKERS
  5. COLORED APPLIANCE HOUSINGS

(D)
(A)
103
thermosets
alkyds
phenolics
aminos
polyesters
urea
polyimides
epoxies
silicones
104
AMINOS
gtgt UREA AND MELAMINE gtgt ARE POLYMERS FORMED
BY THE REACTION OF FORMALDEHYDE WITH
COMPOUNDS CONTAINING THE AMINO GROUP gtgt ARE
GENERALLY HARD AND RIGID gtgt RESISTANT TO CREEP
AND ABRASION
105
MELAMINE
gtgt VERY HARD AND SCRATCH RESISTANT gtgt
SELF-EXTINGUISHING gtgt GOOD ELECTRICAL
INSULATOR gtgt OPAQUE TO TRANSPARENT gtgt WIDE RANGE
OF COLORS (INCLUDING WHITE AND PASTEL) gtgt
RESISTANT TO STAINING, WATER AND DETERGENTS
106
DESIGN CONSIDERATIONS -- melamine
gtgt LONGTERM OXIDATION RESISTANCE IS POOR gtgt
ATTACKED BY STRONG ACIDS AND BASES gtgt POOR
DIMENSIONAL STABILITY, PARTICULARLY OVER 80OC
107
UREAS
gtgt LOW COST gtgt HARD, RIGID AND SCRATCH
RESISTANT gtgt HAVE WIDE RANGE OF COLORS (INCLUDING
PASTEL) AND FROM OPAQUE TO TRANSPARENT gtgt
HAVE GOOD ELECTRICAL AND WEAR RESISTANCE gtgt
RESISTANT TO MOST SOLVENTS AND COMMON
REAGENTS gtgt HAVE FREEDOM FROM TASTE AND ODOR
(COMPATIBLE WITH FOODSTUFFS) gtgt UNAFFECTED BY
DETERGENTS gtgt WATER ABSORPTION CAUSES ITS
DIMENSIONAL STABILITY TO WEAKEN
108
DESIGN CONSIDERATIONS -- ureas
gtgt LOWER HUMIDITY RESISTANCE THAN MELAMINE gtgt
NOT RECOMMENDED FOR USE OUTSIDE RANGE OF --
55 TO 77OC gtgt LOW IMPACT STRENGTH AT ROOM
TEMPERATURE
109
AMINOS ( GENERAL APPLICATIONS )
  1. SMALL APPLIANCE HOUSINGS
  2. COUNTERTOPS
  3. TOILET SEATS
  4. HANDLES
  5. DISTRIBUTOR CAPS

(C)
(A)
110
UREAS ( APPLICATIONS )
  1. ELECTRICAL EQUIPMENT (PLUGS AND SWITCHES)
  2. BUTTONS AND BUCKLES
  3. KNOBS
  4. KITCHEN WARE, SAUCERS AND PLATES
  5. TOYS

(E)
(B)
(D)
111
thermosets
alkyds
phenolics
aminos
polyesters
urea
polyimides
epoxies
silicones
112
EPOXIES
gtgt STRONG ADHESIVE PROPERTIES, ESPECIALLY TO
METALS AND WOOD gtgt HIGH RESISTANCE TO CRACKING
WHEN USED TO ENCAPSULATE METAL
COMPONENTS gtgt GOOD RESISTANCE TO WATER AND
COMMON REAGENTS gtgt EXCELLENT RESISTANCE TO
HEAT gtgt GOOD ELECTRICAL INSULATION AND
DIMENSIONAL STABILITY (BETTER THAN
POLYESTER) gtgt GOOD DIELECTRIC STRENGTH
113
DESIGN CONSIDERATIONS -- epoxies
gtgt HIGH COST gtgt LIMITED TO 180 TO 240OC gtgt POOR
WEATHERING RESISTANCE gtgt SENSITIVE TO
MOISTURE gtgt SUSCEPTIBLE TO UV DEGRADATION AND
NOT USED IN EXTERNAL APPLICATIONS WHERE
APPEARANCE IS OF PRIME IMPORTANCE
114
EPOXIES ( APPLICATIONS )
  1. ADHESIVES FOR GLUING METALS
  2. TOOLS AND DIES
  3. PRESSURE VESSELS
  4. ROCKET MOTOR CASINGS
  5. TANKS

(C)
(E)
115
thermosets
alkyds
phenolics
aminos
polyesters
urea
polyimides
epoxies
silicones
116
PHENOLICS
gtgt MOST WIDELY USED THERMOSET gtgt INEXPENSIVE gtgt
BRITTLE BUT RIGID gtgt GOOD DIMENSIONAL STABILITY
OVER A WIDE TEMPERATURE RANGE gtgt GOOD
COMPRESSIVE STRENGTH gtgt VERY LOW WATER
ABSORPTION gtgt HAVE HIGH RESISTANCE TO HEAT,
WATER, ELECTRICITY AND CHEMICALS (WEAK
ACIDS AND MOST DETERGENTS) gtgt LOW
SMOKE AND TOXIC EMISSIONS
117
DESIGN CONSIDERATIONS -- phenolics
gtgt FORMS ARE HARD BUT BRITTLE (HIGH
BREAKAGE RATES DURING TRANSPORTATION HAVE
BEEN REPORTED) gtgt NOT STABLE IN THE PRESENCE OF
ALKALIS OR STRONG OXIDIZING ACIDS gtgt
ELECTRICAL PROPERTIES AND SURFACE FINISH
AFFECTED BY HOT, WET CONDITIONS gtgt LIMITED TO
DARK COLORS OWING TO OXIDATION DISCOLORATION
118
PHENOLICS ( APPLICATIONS )
  1. TELEPHONES
  2. KNOBS, HANDLES
  3. WIRING DEVICES
  4. BOND MATERIAL TO HOLD ABRASIVE GRAINS TOGETHER IN
    GRINDING WHEELS

(B)
(A)
119
thermosets
alkyds
phenolics
aminos
polyesters
urea
polyimides
epoxies
silicones
120
UNSATURATED POLYESTERS
gtgt UNSATURATED POLYESTERS gtgt LOW COST RAW
MATERIAL AND EASILY AVAILABLE gtgt GOOD IMPACT
RESISTANCE AND SURFACE HARDNESS gtgt GOOD
RESISTANCE TO WATER AND COMMON REAGENTS gtgt
EXCELLENT HEAT RESISTANCE gtgt GOOD ELECTRICAL
INSULATION gtgt GENERALLY REINFORCED WITH GLASS OR
FIBERS
121
UNSATURATED POLYESTERS
(VERSUS THERMOPLASTIC TYPE)
gtgt HAVE LOWER CREEP gtgt NON-BURNING GRADES
AVAILABLE, WITHOUT INCORPORATING ADDITIVES
NECESSARY WITH SOME THERMOPLASTICS gtgt
BETTER IMPACT AT SUBZERO TEMPERATURES,
DEMANDED IN NEW LEGISLATION COVERING
ELECTRICAL EQUIPMENT, RELATIVE TO
THERMOPLASTICS gtgt BETTER THERMAL
CHARACTERISTICS THAN ABS
122
DESIGN CONSIDERATIONS -- polyesters
gtgt MORE EXPENSIVE RAW MATERIAL THAN
PHENOLICS gtgt TENSILE STRENGTH FALLS OFF WITH AN
INCREASE IN TEMPERATURE
123
POLYESTERS ( APPLICATIONS )
  • FISHING RODS
  • LAMPSHADES
  • CAR BODIES
  • HELMETS
  • BOATS
  • LUGGAGE
  • CHAIRS
  • SWIMMING
  • POOLS

(G)
(A)
(B)
124
thermosets
alkyds
phenolics
aminos
polyesters
urea
polyimides
epoxies
silicones
125
POLYIMIDES
gtgt HAVE EXCELLENT ELECTRICAL INSULATION gtgt
SOLVENT RESISTANT gtgt FLAME RESISTANT gtgt HAVE VERY
GOOD ABRASION AND HEAT RESISTANCE gtgt RESISTANT TO
DEGRADATION BY OXIDATION AND TO MOST
CHEMICALS, EXCEPT FOR STRONG BASES gtgt HAVE CREEP
RESISTANCE gtgt HAVE LOW FRICTION
126
DESIGN CONSIDERATIONS polyimides
gtgt GENERALLY, AT ELEVATED TEMPERATURES, THEY
EXHIBIT GOOD MECHANICAL, ELECTRICAL AND
PHYSICAL PROPERTIES
127
POLYIMIDES ( APPLICATIONS )
  1. PUMP COMPONENTS (BEARINGS, SEALS, PISTON RINGS)
  2. COMPRESSOR SEATS IN JET ENGINES AND AEROSPACE
    PARTS
  3. SOLDERING AND WELDING EQUIPMENT
  4. SPORTS EQUIPMENT
  5. SAFETY VESTS

(C)
(E)
128
thermosets
alkyds
phenolics
aminos
polyesters
urea
polyimides
epoxies
silicones
129
SILICONES
gtgt BECAUSE OF THE SILICON OXIDE LINKAGE, THE
PROPERTIES OF SILICONES HAVE WIDER
TEMPERATURE CAPABILITY, IMPROVED WATER
RESISTANCE AND BETTER OXIDATVE STABILITY THAN
POLYMERS WHICH DEPEND ON CARBON
130
SILICONES
gtgt WEATHER RESISTANT gtgt GOOD ELECTRICAL
PROPERTIES MAINTAINED OVER A WIDE RANGE OF
TEMPERATURE AND FREQUENCY gtgt VERY LOW WATER
ABSORPTION gtgt CAN SUSTAIN HIGH TEMPERATURES AND
HUMIDITIES gtgt GOOD CHEMICAL RESISTANCE gtgt
EXCELLENT DIELECTRIC PROPERTIES EVEN WHEN
EXPOSED TO MOISTURE
131
DESIGN CONSIDERATIONS -- silicones
gtgt LOW STRENGTH gtgt NOT RESISTANT TO STRONG
ALKALIS gtgt ATTACKED BY HALOGENATED SOLVENTS gtgt
HIGH COST
132
SILICONES ( APPLICATIONS )
  1. WATERPROOF COATINGS FOR FABRICS
  2. HYDRAULIC FLUIDS
  3. SWITCH PARTS
  4. ELECTRICAL COMPONENTS REQUIRING STRENGTH AT
    ELEVATED TEMPERATURES
  5. OVEN GASKETS

(A)
133
elastomers
gtgt SPECIAL CLASS OF POLYMERS DISPLAYING LARGE
AMOUNTS OF ELASTIC DEFORMATION WHEN FORCE IS
APPLIED gtgt COMES FROM TWO TERMS (1) ELASTIC ?
DESCRIBING THE ABILITY OF A MATERIAL
TO RETURN TO ITS ORIGINAL SHAPE
WHEN A LOAD IS REMOVED (2) MER ?
FROM POLYMER (MANY PARTS)
134
ENTROPY
  • DEFAULT
  • MOLECULES ARE IN A STATE OF DISORDER
  • WHEN STRETCHED
  • THEY UNCOIL (LIKE SPRINGS) AND BECOME ORDERLY,
    IN THE DIRECTION OF THE FORCE
  • WHEN FORCE IS REMOVED
  • THEY RECOIL AND RETURN TO THEIR ORIGINAL SHAPE

135
THEY LOVE DISORDER (entropy)!
136
elastomers
gtgt THEY CAN BE STRETCHED TO MANY TIMES THEIR
ORIGINAL LENGTH AND CAN BOUNCE BACK TO THEIR
ORIGINAL SHAPE WITHOUT PERMANENT DEFORMATION gtgt
LONG POLYMER CHAINS CROSSLINK DURING CURING AND
ACCOUNT FOR THE FLEXIBLE NATURE gtgt CAN BE
THERMOSETS (REQUIRES VULCANIZATION) OR
THERMOPLASTICS
137
GLASS - TRANSITION TEMPERATURE
gtgt ELASTOMERS ARE AMORPHOUS POLYMERS EXISTING
ABOVE THEIR TG BELOW ROOM TEMPERATURE AMORPHOUS
POLYMER IS AN ELASTOMER (SINCE IT IS SOFT AND
RUBBERY AT ROOM TEMPERATURE) ABOVE ROOM
TEMPERATURE THERMOSPLASTIC, (SINCE IT
IS HARD AND GLASSY)
138
Amorphous and tg
139
GENERAL RULE OF THUMB
ELASTOMERS HAVE LOW TG, WHILE THERMOPLASTICS
HAVE HIGH TG. gtgt THIS ONLY WORKS FOR AMORPHOUS
POLYMERS AND NOT FOR CRYSTALLINE POLYMERS.
140
CROSS-LINKING
  • REVIEW FORMING OF COVALENT LINKS BETWEEN
    DIFFERENT POLYMER CHAINS, JOINING THEM ALL INTO A
    SINGLE NETWORK MOLECULE
  • HELPS ELASTOMER TO BOUNCE BACK BETTER (HARDER TO
    PULL THEM OUT OF THEIR ORIGINAL POSITIONS
  • ? ENVIRONMENTAL ISSUE THEYRE HARDER
    TO RECYCLE

141
ELASTOMERS
rubbers
silicones
polyurethane
142
RUBBERS
gtgt CAPABLE OF RECOVERING FROM LARGE
DEFORMATIONS QUICKLY gtgt TYPES I. NATURAL
RUBBERS II. SYNTHETIC RUBBERS
143
NATURAL RUBBERS
gtgt OBTAINED FROM THE PLANTATION GROWN RUBBER
TREE HEVEA BRASILIENSIS BY TAPPING THE
LATEX- PRODUCING LAYER OF THE TREES INNER
BARK STRUCTURE gtgt LOWEST COST OF ALL
RUBBERS gtgt OLDEST COMMERCIAL ELASTOMERS gtgt
EXCELLENT STRENGTH AND ABRASION RESISTANCE gtgt
VERY GOOD ELECTRICAL INSULATION gtgt VERY GOOD
RESISTANCE TO COLD gtgt LOW SWELLING IN WATER,
ACETONE, ALCOHOL AND VEGETABLE OILS
144
NATURAL RUBBERS
gtgt RESISTANCE TO MOST INORGANIC ACIDS, SALTS
AND ALKALIS gtgt CAN BOND TO METALS WELL gtgt
RELATIVELY EASY TO PROCESS gtgt HIGH FRICTIONAL
PROPERTIES
145
A rubber tree plantation in southern Thailand. 
Each night a new cut is made causing a new flow
of latex.  
146
Latex flow begins.
Latex flows toward a collection cup.
147
Latex begins to flow into the cup.
Latex being coagulated in a pan.
148
Water is rolled out of the cake of fresh rubber.
Fresh and smoked sheets of raw rubber.
149
DESIGN CONSIDERATIONS natural rubbers
gtgt FAIR WEATHER RESISTANCE gtgt LOW HEAT
RESISTANCE gtgt INFERIOR OIL AND UV LIGHT
RESISTANCE gtgt ATTACKED BY CONCENTRATED SULFURIC
ACIDS, HALOGENS AND STRONG OXIDIZING AGENTS
150
NATURAL RUBBERS ( APPLICATIONS )
  1. TIRES
  2. SHOE HEELS
  3. COUPLING
  4. ENGINE MOUNTS
  5. SEALS

(B)
(D)
(A)
151
SYNTHETIC RUBBERS
gtgt HAVE IMPROVED RESISTANCE TO HEAT, GASOLINE
AND CHEMICALS AND HIGHER USEFUL
TEMPERATURE RANGE COMPARED TO NATURAL
RUBBERS gtgt HAVE BEEN DEVELOPED TO REPLACE NATURAL
RUBBER IN A WIDE RANGE OF APPLICATIONS gtgt
EXAMPLES THAT ARE RESISTANT TO OIL NEOPRENE,
NITRILE, URETHANE, SILICONE
152
SYNTHETIC RUBBERS
gtgt TYPES I. STYRENE BUTADIENE RUBBER
(SBR) II. POLYBUTADIENE RUBBER
(BR) III. POLYCHLOROPRENE RUBBER
(CR) IV. (ACRYLO) NITRILE BUTADIENE RUBBER
(NBR) V. BUTYL RUBBER VI. ETHYLENE PROPYLENE
RUBBER (EPR) VII. CHLOROSULFONATED
POLYETHYLENE VIII. FLUOROELASTOMERS IX. POLYISOP
RENE
153
SYNTHETIC RUBBERS
STYRENE BUTADIENE RUBBER (SBR) gtgt LOW COST gtgt
SIMILAR MECHANICAL PROPERTIES TO NATURAL
RUBBER gtgt SUPERIOR AGING CHARACTERISTICS TO
NATURAL RUBBER
154
DESIGN CONSIDERATIONS synthetic rubbers
STYRENE BUTADIENE RUBBER (SBR) gtgt POOR MECHANICAL
PROPERTIES WITHOUT REINFORCING FILLERS gtgt
LESS ABRASION RESISTANT AND RESILIENT THAN
NATURAL RUBBER gtgt SLIGHTLY INFERIOR TENSILE
STRENGTH, AGING AND WEATHERING
CHARACTERISTICS TO NATURAL RUBBER
155
STYRENE BUTADIENE RUBBERS (APPLICATIONS )
  1. CAR TIRES
  2. SHOE SOLES AND HEELS
  3. ELECTRONIC INSULATION

(A)
156
SYNTHETIC RUBBERS
POLYBUTADIENE RUBBER (BR) gtgt GOOD LOW TEMPERATURE
PROPERTIES gtgt VERY LOW TG gtgt FREQUENTLY BLENDED
WITH OTHER ELASTOMERS TO IMPROVE PROPERTIES
(EX. IMPROVE ABRASION RESISTANCE)
157
DESIGN CONSIDERATIONS synthetic rubbers
POLYBUTADIENE RUBBER (BR) gtgt MECHANICAL
PROPERTIES MOSTLY INFERIOR TO OTHER
ELASTOMERS gtgt DIFFICULT TO PROCESS UNLESS
BLENDED gtgt UPPER SERVICE TEMPERATURE LIMITED TO
120OC
158
POLYBUTADIENE RUBBERS (APPLICATIONS )
  1. SHOE HEELS
  2. GASKETS
  3. SEALS

(A)
(B)
159
SYNTHETIC RUBBERS
POLYCHLOROPRENE RUBBER (CR) gtgt GOOD MECHANICAL
AND ELECTRICAL PROPERTIES gtgt SELF-EXTINGUISHING gtgt
REASONABLE RESISTANCE TO HEAT AND OIL gtgt SIMILAR
ABRASION RESISTANCE TO NATURAL RUBBER
160
DESIGN CONSIDERATIONS synthetic rubbers
POLYCHLOROPRENE RUBBER (CR) gtgt MORE EXPENSIVE
THAN NATURAL RUBBER gtgt POOR LOW TEMPERATURE
RESISTANCE gtgt PERMEABILITY INFERIOR TO NATURAL
RUBBER
161
POLYCHLOROPRENE RUBBERS (APPLICATIONS )
  1. CONVEYOR BELTS
  2. BALLOONS
  3. ADHESIVES

(B)
(A)
162
SYNTHETIC RUBBERS
(ACRYLO) NITRILE BUTADIENE RUBBER (NBR) gtgt GOOD
RESISTANCE TO OILS AND PETROL gtgt GOOD RESISTANCE
TO HEAT gtgt RESISTANT TO INORGANIC CHEMICALS gtgt
GOOD ADHESION TO STEEL
163
DESIGN CONSIDERATIONS synthetic rubbers
(ACRYLO) NITRILE BUTADIENE RUBBER (NBR) gtgt NOT
RESISTANT TO OXIDIZING AGENTS gtgt INFERIOR
ELASTICITY TO NATURAL RUBBER gtgt INFERIOR TO
CHLOROPRENE RUBBER IN WEATHERING
RESISTANCE gtgt MORE EXPENSIVE THAN NATURAL RUBBER
AND STYRENE BUTADIENE RUBBER
164
NBR (APPLICATIONS )
  1. FUEL TANKS WITH PETROLEUM

(A)
165
SYNTHETIC RUBBERS
BUTYL RUBBER gtgt COPOLYMERIZATION OF ISOBUTYLENE
AND ISOPRENE gtgt GOOD RESISTANCE TO OZONE
AND HEAT gtgt IMPERMEABLE TO AIR AND OTHER GASES
166
DESIGN CONSIDERATIONS synthetic rubbers
BUTYL RUBBER gtgt LOW RESILIENCE AT ROOM
TEMPERATURE gtgt INFERIOR ABRASION AND TEAR
RESISTANCE gtgt READILY COMBUSTIBLE gtgt DIFFICULT
TO BOND TO METALS gtgt BLENDS WITH NATURAL RUBBER
NOT RECOMMENDED gtgt ATTACKED BY FUELS AND OILS
167
BUTYL RUBBER (APPLICATIONS )
  1. AIRBAGS
  2. CONVEYOR BELTS

(A)
168
SYNTHETIC RUBBERS
ETHYLENE PROPYLENE RUBBER (EPR) gtgt OUTSTANDING
RESISTANCE TO OZONE AND WEATHERING gtgt
LIGHTWEIGHT gtgt EXCELLENT ABRASION RESISTANCE gtgt
ACCEPTS PAINT gtgt GOOD RESISTANCE TO ACIDS, BASES,
SUPERHEATED STEAM AND HOT WATER
169
DESIGN CONSIDERATIONS synthetic rubbers
ETHYLENE PROPYLENE RUBBER (EPR) gtgt MODERATE
ADHESION TO FABRICS AND METALS gtgt VERY POOR OIL
RESISTANCE gtgt TEAR RESISTANCE NOT AS GOOD AS
NATURAL RUBBER BUT SIMILAR TO STYRENE
BUTADIENE RUBBER
170
ETHYLENE PROPYLENE RUBBER (APPLICATIONS )
  1. FOOTWEAR
  2. ELECTRICAL INSULATION

(A)
171
SYNTHETIC RUBBERS
CHLOROSULFONATED POLYETHYLENE gtgt EXCELLENT
RESISTANCE TO CHEMICALS, OZONE AND HEAT gtgt
USED AS COATINGS FOR OTHER RUBBERS AS OZONE
PROTECTION
172
DESIGN CONSIDERATIONS synthetic rubbers
CHLOROSULFONATED POLYETHYLENE gtgt EXPENSIVE gtgt
POOR COMPRESSION SET
173
CHLOROSULFONATED POLYETHYLENE (APPLICATIONS )
  1. TANK LININGS

(A)
174
SYNTHETIC RUBBERS
FLUOROELASTOMERS gtgt COPOLYMERIZATION OF
VINYLIDINE FLUORIDE AND HEXAFLUOROPROPYLENE
gtgt EXCELLENT RESISTANCE TO OIL, CHEMICALS AND
HEAT gtgt GOOD RESISTANCE TO ABRASION, OZONE AND
WEATHERING gtgt GOOD RESISTANCE AND ADHERENCE
TO FABRICS AND METALS gtgt VERY USEFUL HIGH
TEMPERATURE (UP TO 232OC)
175
DESIGN CONSIDERATIONS synthetic rubbers
FLUOROELASTOMERS gtgt VERY EXPENSIVE)
176
FLUOROELASTOMERS (APPLICATIONS )
  1. O-RINGS IN AIRCRAFTS
  2. GASKETS

(A)
177
SYNTHETIC RUBBERS
POLYISOPRENE gtgt POLYMERIZATION OF ISOPRENE gtgt
SAME COMPOSITION, PROPERTIES AND
APPLICATIONS AS NATURAL RUBBERS
178
ELASTOMERS
rubbers
silicones
polyurethane
179
SILICONES
gtgt FROM SILICON, OXYGEN, AND ONE OR MORE
ORGANIC GROUPS gtgt RUBBER IS UNIQUE IN NOT HAVING
A CARBON BACKBONE (EXTENDS USEFUL
TEMPERATURE NOTABLY) gtgt TG AS LOW AS
127OC TO gtgt CAN BE USED IN SERVICE TEMPERATURES
OF 200OC OR MORE FOR SEVERAL YEARS gtgt HAVE
THE HIGHEST USEFUL TEMPERATURE RANGE
---100OC TO 315OC gtgt GENERALLY INFERIOR TO OTHER
ELASTOMERS gtgt WEATHER WELL
gtgt RESISTS CHEMICALS AND HEAT
180
SILICONES
gtgt EXCELLENT ELECTRICAL PROPERTIES OVER A WIDE
RANGE OF HUMIDITY AND TEMPERATURE gtgt EXCELLENT
VIBRATION DAMPING, AND REASONABLE PHYSICAL
PROPERTIES SUCH AS TENSILE STRENGTH AND
ELONGATION
181
DESIGN CONSIDERATIONS silicones
gtgt POOR ABRASION RESISTANCE
182
SILICONES ( APPLICATIONS )
  1. THERMAL INSULATION APPLICATIONS
  2. SEALS
  3. GASKETS
  4. HIGH-TEMPERATURE ELECTRICAL SWITCHES
  5. O-RINGS

(C)
183
ELASTOMERS
rubbers
silicones
polyurethane
184
POLYURETHANES
gtgt CONSIST OF ISOCYANATE WITH HYDROXYL GROUPS
LIKE POLYESTERS AND POLYETHERS gtgt HIGH
STRENGTH, STIFFNESS AND HARDNESS gtgt EXCEPTIONAL
RESISTANCE TO ABRASION, CUTTING, TEARING gtgt
HAVE HIGH RESISTANCE TO HEAT AND
DEGRADATION BY ATMOSPHERIC OXYGEN AND
OZONE gtgt SUITABLE IN TROPICAL AREAS --- HAVE
MOLD, MILDEW AND FUNGUS RESISTANCE gtgt HAVE
THE BEST RESISTANCE TO GAMMA RADIATION gtgt
HAVE A WIDE RANGE OF HARDNESS --- CAN BE SOFT
AS AN ERASER AND CAN BE HARD AS A GOLF
BALL
185
POLYURETHANES
gtgt GOOD INSULATING PROPERTIES gtgt REMAIN FLEXIBLE
AT VERY LOW TEMPERATURES AND POSSESS
OUTSTANDING RESISTANCE TO THERMAL SHOCK gtgt
RESISTS CRACKING UNDER REPEATED FLEXING gtgt HAVE
BETTER IMPACT RESISTANCE THAN ALMOST ALL
PLASTICS WHEN AT THEIR HIGHEST HARDNESS
LEVELS gtgt THEY CAN BE BONDED TO MOST METALS, WOOD
AND PLASTICS
186
DESIGN CONSIDERATIONS polyurethane
gtgt WIDE RESISTANCE TO CHEMICAL ATTACK (OIL OR
CHEMICALS) EXCEPT FOR STRONG ACIDS AND
ALKALIS gtgt FRICTION AGAINST NON-LUBRICATED
SURFACES GENERALLY DECREASE WITH INCREASING
HARDNESS (A HIGH COEFFICIENT IS
VALUABLE FOR SUCH PRODUCTS AS SOLID
INDUSTRIAL TIRES, FEED ROLLERS, DRIVE
ROLLERS, ETC.)
187
POLYURETHANE ( APPLICATIONS )
  1. SEALS
  2. GASKETS
  3. AUTO BODY PARTS
  4. CUSHIONING
  5. DIAPHRAGMS FOR RUBBER FORMING OF SHEET METALS

(C)
(A)
188
Category Principal characteristics Principal characteristics Structural Characteristics Factors which affect characteristics Typical Examples
Category Mechanical Thermal Structural Characteristics Factors which affect characteristics Typical Examples
Thermoplastics Rigid at room temperature Reversible softening on heating and flow Rigid chain Composition of polymer chain, molecular weight and distribution, presence of branching Polystyrene, ABS, Polycarbonate Polysulfones
Thermoplastics Rigid at room temperature Reversible softening on heating and flow Crystallization present As above, plus degree of crystallization governed by presence branching nature of chain constituents Polyethylene Polypropylene Polyamides Moldable polyesters
Thermosetting plastic Rigid at room temperature No softening on heating after initial molding Chemically cross-linked Reacting constituents fillers and reinforcements Phenol formaldehyde Urea formaldehyde Melamine formaldehyde Unsaturated polyesters Epoxy resins
Elastomers Flexible at Room temperature Increasing tendency to flow on heating Flexible chains and on crystallization, chains present in coiled form. Lightly cross-linked Composition of the polymer chain, molecular weight, molecular weight distribution, degree of cross-linking Natural rubber Various synthetic rubbers
About PowerShow.com