Santa Rosa Junior College
Spring 2009
Engr 45 – Materials Science
POLYMERS
By: Tesfaberhan Habtemariam,
Omid Borjian and Elena Foster
Spring 2009
Table of contents
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What is a polymer
How are polymers created in lab? (Video)
What types of Polymers are there?
What is the chemical structure?
How are polymers used?
What are the physical and chemical properties of
polymers
• Nanopolymers
• Shape Memory Polymers (SMPs)
• Light emitting polymers (OLED/PLED/LEP)
What is a polymer?
• A polymer is a large
molecule composed of
repeating structural units
typically connected by
covalent chemical bonds
Different types of Polymers Polyethylene
• Most common and
important polymer;
bags, insulation for
wires, squeeze bottles
High density
Low density
Different types of Polymers Polypropylene
Fibers, indoor-outdoor
carpets, bottles
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Max T: 275°F/135°C
Min T: 32°F 0°C
Melting P: 338°F 170°C
Tensile Strength: 4,500 psi
Hardness: R95
UV Resistance: Poor
Excellent resistance to dilute and
concentrated Acids, Alcohols, Bases
and Mineral Oils
• Good resistance to Aldehydes, Esters,
Aliphatic Hydrocarbons, Ketones and
Vegetable Oils
• Limited resistance (for short term use
only) to Aromatic and Halogenated
Hydrocarbons and Oxidizing Agents
Different types of Polymers Polystyrene
• Styrofoam, inexpensive
household goods,
inexpensive molded
objects
Properties of EPS Molded Packaging
Stress@10% Flexural Tensile Shear
Density Compression Strength Strength Strength
(pcf)
(psi) (psi)
(psi)
(psi)
1
13
29
31
31
1.5
24
43
51
53
2
30
58
62
70
2.5
42
75
74
92
3
64
88
88
118
3.3
67
105
98
140
4
80
125
108
175
Different types of Polymers –
Polyvinyl chloride (PVC)
• Synthetic leather, clear
bottles, floor covering,
water pipes
• Max T: 158°F 70°C
• Min T: -13°F -25°C
• Melting P: 176°F 80°C
• Tensile Strength: 6,500
psi
• Hardness: R105
• UV Resistance: Good
Different types of Polymers –
Polytetrafluoroethylene (Teflon)
• Nonstick surfaces,
chemically resistant
films
•Max T: 572°F 300°C
•Min T: 392°F -200°C
•Melting P: 626°F 330°C
•Tensile Strength: 6,240 psi
•Hardness: R58
•UV Resistance: Excellent
Different types of Polymers –
Poly(methylmethacrylate)(Lucite,
Plexiglas)
• Unbreakable “glass,”
latex paints
• Clear, colorless polymer
used extensively for
optical applications
Different types of Polymers –
Polyacrylonitrile (Orlon, Acrilan,
Creslan)
• Fiber used in sweaters,
blankets and carpets
• most commonly used in
fiber form. Since it
softens only slightly
below its thermal
degradation
temperature, it must be
processed by wet or dry
spinning rather than
melt spinning.
Different types of Polymers –
Poly(vinyl acetate)(PVA)
• Adhesive, latex paints,
chewing gum, textile
coatings
primarily used in adhesives,
both emulsion and hot-melt
types. It is also used in
water based emulsion
paints.
Different types of Polymers –
Natural Rubber
• Polymer cross-linked
with sulfur
(vulcanization)
Different types of Polymers –
Polychloroprene (neoprene rubber)
• Cross-linked with ZnO; resistant to oil
and gasoline
• Resists degradation from sun, ozone
and weather
• Performs well in contact with oils and
many chemicals
• Remains useful over a wide
temperature range
• Displays outstanding physical
toughness
• Resists burning better than exclusively
hydrocarbon rubbers
• Outstanding resistance to damage
caused by flexing and twisting
Different types of Polymers –
Styrene butadiene rubber (SBR)
• Styrene butadiene rubber
(SBR) is the largest volume
synthetic rubber. With over
70% of SBR being consumed
in the manufacture of tires
• Elongation (%) 150
• Melting point oC 120
• Specific gravity 1.04
• Tensile strength (Psi) 400
Nanopolymers
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Polymer nanocomposites (PNC) is a polymer or copolymer having dispersed in its
nanoparticles. These may be of different shape (e.g., platelets, fibers, spheroids),
but at least one dimension must be in the range of 1 to 50 nm.
PNC's belong to the category of multi-phase systems (MPS, viz. blends,
composites, and foams) that consume nearly 95% of plastics production. These
systems require controlled mixing/compounding, stabilization of the achieved
dispersion.
increase in surface are-to-volume ratio, which increases as the particles get
smaller, leads to an increasing dominance of the behavior of atoms on the surface
area of particle over that of those interior of the particle. Because of the higher
surface area of the nano-particles the interaction with the other particles within
the mixture is more and this increases the strength, heat resistance etc.
Silicon nanospheres, fullerens (buckyballs), carbon nanotubes (buckytubes),
graphene, etc
Some areas of nanopolymer
research and use
•Materials that don’t normally stick together can
be bonded by using a one-nanometer-high
layer of self-assembling polymer chains. The
nanoglue consists of chains of carbon and
hydrogen atoms customized with appropriate
molecules at the ends. This one has chains with
sulfur at one end, to join copper components
with other materials on computer chips (can be
customized) . This glue is 10 times thinner than
current chips’ glue.
• Electro-Spinning is a process that utilizes high
electrical voltage to produce polymer fibers
from polymer solutions or melts. It produces
ultra-fine fibers, with huge surface-to –volume
ratio, which have great application potentials in
many fields such as protective clothing, air
filtration, sensors, drug delivery system,
sensors.
Some areas of nanopolymer
research and use
• Adding nanoparticulates to a polymer matrix can enhance its
performance, often in very dramatic degree, by simply capitalizing on the
nature and properties of the nanoscale filler ( nanofilled polymer
composites ). For example, reinforcing a polymer matrix by much stiffer
nanoparticles of ceramics, clays, or carbon nanotubes; also to add new
properties like fire resistance or accelerated biodegradability.
• Bio-hybrid polymer nanofibers : Many technical applications of biological
objects like proteins, viruses or bacteria such as chromatography, optical
information technology, sensorics, catalysis and drug delivery require
their immobilization. Carbon nanotubes, gold particles and synthetic
polymers are used for this purpose. This immobilization has been
achieved predominantly by adsorption or by chemical binding and to a
lesser extent by incorporating these objects as guests in host matrices
Some areas of nanopolymer
research and use
Self-Assembling Polymer
Nanostructures
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Formed by dissolving a coil-like polymer such as
polystyrene in a fast-evaporating solvent such as
benzene; placed on a glass slide, air is directed across it
as the solvent evaporates. The temperature drops,
producing a three-dimensional pattern of closely
packed water droplets preserved in the polymer film.
The water then evaporates layer by layer, leaving an
interconnected network of ‘perfect’ air bubbles.
Application: in optics, using structures with pore
dimensions comparable to the wavelength of visible
light. That makes them of interest as potential photonic
band gap materials, optical waveguides, beam-steering
systems -- and even arrays of dye lasers. Photonic band
gap (PBG) materials are a new class of dielectrics which
are the photonic analogues of semiconductors (used for
optical switches). (like single crystal colloidal silica in a
silicon wafer; all-optical information processing)
Image shows air bubbles in selfassembled polymer structure.
Shape Memory Polymers (SMPs)
• are polymeric smart materials which have the ability to return from a
deformed state (temporary shape) to their original (permanent) shape
induced by an external stimulus
• Two properties:
– strain recovery rate (Rr)
– strain fixity rate (Rf).
The strain recovery rate describes the ability of the material to memorize its
permanent shape, while the strain fixity rate describes the ability of
switching segments to fix the mechanical deformation.
• Triggers
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Temperature
pH
Light
Magnetic or electric field
Shape Memory Polymers (SMPs)
• where N is the cycle number,
Em is the maximum strain
imposed on the material, and
Ep (N) and Ep (N-1) are the
strains of the sample in to
successive cycles in the
stress-free state before yield
stress is applied.
Light Emitting Polymers
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also called organic light emitting
diode (OLED)
an LED whose emissive
electroluminescent layer is
composed of a film of organic
compounds. The layer contains a
polymer that allows organic
compounds to be deposited. They
are deposited in rows and columns
onto a flat carrier by a simple
"printing" process. The resulting
matrix of pixels can emit light of
different colors.
or involves an electroluminescent
conductive polymer that emits light
when connected to an external
voltage source; used as a thin film
for full-spectrum color displays
Light Emitting Polymers
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Advantages:
– low energy requirements; flexibility
– can be printed onto any suitable substrate using an inkjet printer
– greater range of colors, gamut, brightness, contrast and viewing angle than LCDs
– pixel colors appear correct and unshifted, even as the viewing angle approaches 90
degrees from normal
– LCDs use a backlight and cannot show true black, while an off OLED element
produces no light and consumes no power
– OLEDs also have a faster response time than standard LCD screens. Whereas the
fastest LCD displays currently have a 2ms response time (manufacturer's quote),
an OLED can have less than 0.01ms response time.
Disadvantages:
– limited lifetime of the organic materials (5 years at 8 hours a day)
– To increase lifetime: a metal membrane helps deliver light from polymers in the
substrate throughout the glass surface more efficiently than current OLEDs. The
result is the same picture quality with half the brightness and a doubling of the
screen's expected life (exceeding the lifetime of LCDs)
– Water will damage or destroy the OLED; Therefore, improved sealing processes are
important for practical manufacturing and may limit the longevity of more flexible
displays.
Refrences
http://farm4.static.flickr.com/3285/2751103590_3b4dc649ef.jpg?v=1218400891
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http://www.frugalyankee.com/files/bubble_gum__by_mycolsayz.jpg
http://www.vikingfootwear.com/arch/_img/9071712.jpg
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http://www.dupontelastomers.com/products/neoprene/neoprene.asp
http://www.icis.com/v2/chemicals/9076465/styrene-butadiene-rubber.html