Proceedings International Conference On Advances In Engineering And Technology
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ADVANCED POLYMER MATERIALS IN SCIENCE AND ENGINEERING Ch. Rajyalakshmi, Asst.Prof., Department of Basic Sciences, Vishnu Institute of Technology, Bhimavaram-2, W.G.Dt, A.P Email: rajyalakshmi.ch@gmail.com
ABSTRACT---Materials
have
always
played
a
Key
words:
Materials, polymers,
Engineering
applications,
thermally
conducting,
significant and defining role in human development,
Advanced
from the Stone Age to the material world of today.
photoconducting,
Materials are central to our prosperity and new
electroluminescent, electrically conducting polymers.
photonic,
composite,
materials hold the key to our future development. Material engineers therefore have an essential role in
INTRODUCTION
developing the materials of today and the future and in taking performance to the next level. Material related
Polymers are macromolecules having very
issues can be found in all areas of life and engineering
large chains, contain a variety of functional groups,
e.g. in biomedical, telecommunications, aeronautical,
can be blended with low and high molecular weight
construction, chemical and mechanical, and in all
materials. Polymers are becoming increasingly
aspects of a products life, from an idea or discovery to a
important in the field of drug delivery. Advances in
prototype or finished product and recycling. In the puzzle of innovation, material engineers focus on the application of materials, where they test, develop and modify materials that are used in a wide range of
polymer science have led to the development of several novel drug delivery systems. A proper consideration of surface and bulk properties can aid
products, from jet engines and snow skis to smart
in the designing of polymers for various drug
phones and diapers. Most of the materials are prepared
delivery applications.
from polymers.
The
commercial
applications
of
polymers have increased over the years, for a wide
Polymers with good mechanical properties
variety of engineering and medical uses. The demand
have replaced conventional materials such as metals,
for polymers with engineered properties for specific end
wood or glass for structural applications
uses increased, resulting in the development of new materials based on polymers. Such materials include
Engineeing and specialty thermo plastics
electrically thermally conducting polymers, photo
offer some remarkable properties like high thermal
conducting
stability, high flexural, tensile and impact strength,
polymers,
photonic
materials,
electroluminescent polymers, electrically conducting and composite polymers. This paper reviewed the some of advanced polymers and their applications in engineering sciences.
ISBN NO: 978 - 1503304048
low creep compliance and good chemical resistance as compared to commodity plastics like polystyrene and polyolefines and that too with reasonable price
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Proceedings International Conference On Advances In Engineering And Technology
www.iaetsd.in
tags. Hence these polymers offer in many cases a
and ABS soften close to 1000c and hence cannot be
viable alternative for metals, especially where high
used for load bearing applications. Though polymers
strength-to-weight ratio is a prime consideration, as
are stable even upto 3000c in the absence of air or
in aerospace and automotive applications.
oxygen they are susceptible to atmospheric oxidation particularly at higher temperatures, which further
Engineering polymers generally include
reduces their usefulness at higher temperatures. The
those polymers which are used in the manufacture of
need for thermally stable polymers is growing in
premium plastic products that exhibit high impact
electrical
strength, high temperature resistance, high chemical
applications, and aerospace industries. Polymers for
resistance and such special properties. Example
high temperature applications should have high
aliphatic
Nylon66),
melting point, high degree of crystallinity and high
polysulfones, polycarbonates, Acrylonitrile butadiene
bond dissociation energy. The presence of aromatic
and styrene (ABS) resin,poly phenylene oxide resin,
rings in the polymer backbone enhances the thermal
poly p-phenylene sulfide, fluroplastics (teflon), and
stability as well as rigidity. Some of the commonly
polyesters. These engineering plastics are generally
used high temperature resistant polymers include
priced 1 to 5 times the cost of the commodity
polysiloxanes, fluoropolymers (PTFE), aromatic
plastics.
polymers
polyamides
(Nylon-6,
insulator,
construction,
(polyphenylene,
transport
Bisphenols
A,
polycarbonate, polyphenylenevinylene), heteroatom Speciality polymers are usually priced at 10 times more than the commodity plastics. Examples are
polyetherimide,
polybismaleimides,
ionic
polymers, polyphosphazines, poly aryl ether ketones,
containing polymers such as polyphenylene oxide, polyphenylene sulphide, polysulphones, poly p hydroxy benzoic acid, polyimides, polyamides such as Nomex and Kevlar, etc.
polyarylates and related aromatic polyesters and ultra high molecular weight polyethylene. These polymers
Photo conducting polymers
exhibit exclusively remarkable performance in certain special, limited but critical applications such
The ability of certain materials to be
as in aerospace composites, membrane for gas liquid
electrically conductive on exposure to light is known
separations, fire retardant textile fabrics used by fire
as photoconductivity. Typically these materials are
fighters and race car drivers and as sutures and
good insulators in the dark but become electrically
surgical implant. Polymides represent the most
conductive when exposed to light because they are
important group of speciality polymers. This paper
capable of absorbing electromagnetic radiation to
reviewed the some of advanced polymers and their
generate charge carriers and facilitate the migration
applications in engineering sciences.
of these carriers to the electrodes. Photoconducting and charge transporting polymers are of p-type or n-
Thermally stable polymers
type depending on the majority carrier. Most of the photoconducting polymers are p-type as thy transport
Most commonly used polymers as plastics such as polyethylene, polystyrene, polyvinyl chloride
ISBN NO: 978 - 1503304048
only
holes.
photoconducting
An
important
polymer
is
example
of
poly(N-Vinyl
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Proceedings International Conference On Advances In Engineering And Technology
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carbazole)(PVK). PVK is an insulator in dark but
properties, ease of moulding and low water
becomes conducting on exposure to ultraviolet
absorption.
radiation. The photoconductive response of the polymer may be extended to visible and infrared
Electroluminescent polymers
radiation by incorporating electron acceptors such as Electroluminescence
2,4,7-trinitrofluorenone or sensitizing dyes. Other examples of photoconducting polymers include polyp-phenylene sulphide, polyvinylpyrene and polymers containing arylamine groups and inorganic polymers such
as
poly {bis(2-naphthyloxy)phosphazene}.
Photo conducting polymers are of importance in laser printers,
xerographic
copiers
and
duplicator
refers
to
the
phenomenon of production of light by electrical excitation
as
seen
in
a
large
number
of
semiconductors. The process occurs as electrons from one electrode are captured by holes at the other electrode followed by Radiative decay of the excited electron-hole combine (exciton).
machines.
Polymers
with
conjugated pi
electron
systems such as poly-p-phenylene vinylene (PPV)
Photonic polymers
exhibit
electroluminescence.
Electroluminescent
Polymers with non linear optical properties,
polymers have potential applications in light emitting
i.e, optical properties vary with the intensity of the
diode (LED) devices and colour pixels in ink-jet
light (glass in contrast is linear in its optical
printing.
properties) have a variety of uses such as photo responsive sun glasses and optical processing and storage of computer data (as in CD-ROM and WORM devices).polymers with extended pi electron structures exhibit non-linear optical properties when the electrons are optically excited. Photonic materials include 6F-polyimide and 4-methoxy-4’-nitrostilbene moiety connected by a six carbon spacer.
should have high transparency, non-scattering, low water absorption and permeability, low stress, stable,
tough
and
hard
surface
characteristics and should be mouldable with high accuracy at a fast throughput. Acrylic polymers have good optical properties but have high water absorption
characteristics.
Genrally
polymers
including
plastics,
elastomers and fibers are regarded as insulators because of the intrinsic property of carbon carbon covalent bonds and were used as insulating materials in electric wires. Polyethylene, PVC, rubber used as insulating sheath. Under certain circumstances they
Polymers used in optical data storage discs
thermally
Electrically conducting polymers
Polycarbonate
and
transparent amorphous polyolefins have good optical
can be made to behave like a metal. Conductivity generally increases with decreasing band gap. Metals have zero band gaps, whereas insulators like many polymers have large band gap which hinder electron flow. By careful design of the chemical structure of the polymer backbone, it may be possible to obtain band gaps as low as 0.5 to 1ev. In becoming electrically conductive its electron need to be free to move. The polymer should have conjugated double bond and the polymer has to be disturbed either by
ISBN NO: 978 - 1503304048
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Proceedings International Conference On Advances In Engineering And Technology
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removing electron from oxidation or inserting
These are used in telecommunication systems (LED),
electron on reduction of polymer. The process is
in electromagnetic screening materials, in electronic
known as doping. Extrinsically conducting polymers
devices such as transistors and diodes, in wiring in
are polymers whose conductivity is due to externally
aircrafts and aerospace components, in solar cells
added ingredients. They are conductive element filled
and used as biosensors in metabolic reactions and
polymers and blended conducting polymers. In case
drug delivery system for human body, in photo
of
the
voltaic devices, in non linear optical material, and in
conducting materials like carbon black, metal oxides,
molecular wires and molecular switches. Conducting
etc. are added to the polymers. In case of blended
polymers such as polyfuran and polythiophene have
conducting polymers, the conducting polymers are
profound uses in humidity sensors and as radiation
mixed with conventional polymer.
detectors as well as gas sensors.
Conductive
element
filled
polymers,
Some important electrically conducting
Composites
polymers are poly sulphur nitrile PSN, Polyacetylene PA,
Poly-p-phenylene
PPP,
polypyrrole
A composite is multiphase material that
PPY,
exhibits a significant proportion of the properties of
polythiophene PTh, polyaniline PAni, etc.
both Conducting polymers have many uses
the constituent
engineers
haves
materials.
designed
Scientists and
various
composite
because they are light weight, easy to process and
materials by the combination of metals, ceramics and
have good mechanical properties. They are used in
polymers
chargeable light weight batteries based on perchlorate
extraordinary materials having combination of
doped polyacetylene lithium systems. These are
superior
approximately 10 times lighter than conventional
toughness, stiffness and high temperature strength.
lead storage batteries. They have flexibility to fit into
Fibre reinforced composites are those composites in
different designs. In optical display devices, based on
which the dispersed phase is in the form of fibre.
polythiophene and polyaniline. When the structure is
Technologically these composistes are very important
electrically biased, the optical density of the film
as they provide high strength and stiffness are their
changes and its colour changes. Such electrochromic
high specific strength and high specific modulus.
systems
faster
Fibre glass composites are widely used in automotive
switching time and better viewing than conventional
parts, marine bodies, storage tanks, plastic pipes and
liquid display device. Polyaniline, due to redox
industrial floorings. Fibre glass reinforced plastics are
activity in conducting state, is green; under reducing
extensively used in transportation industries to reduce
condition, it is in yellow colour, and oxidizing
vehicle weight and boost fuel efficient. Carbon fibers
condition, it apprears blue. A LED consists of a
have much higher specific modulus than glass fibers
semiconductive polymer in the middle and at the
and possess better resistance to temperature and
other end a thin metal foil as electrode. When a
corrosive chemicals. However, carbon fibres are
voltage is applied between the electrodes, the
more expensive and have only limited short fiber
semiconductive polymer will start emitting light.
utilization. The aircraft industry is currently using
produce
ISBN NO: 978 - 1503304048
colour
displays
with
to
produce
mechanical
a
new
generation
characteristics
such
of
as
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Proceedings International Conference On Advances In Engineering And Technology
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carbon reinforced composites. Composite materials haves evolved as sophisticated materials. The extent of mechanical properties that can be attained with carbon fibres depends on crystallinity and the structure which in turn depend upon the quality and composition of the starting material and on the production
technology.
Reinforcing
fibers
are
relatively new entrants in industry. CONCLUSION Advanced
Polymes
offers
a
range
of materials designed for use across a broad spectrum of products and industries. Advanced polymer products can improve strength and durability; impart water, stain and chemical resistance; enhance color, increase gloss, reduce dust and dirt pick-up, promote adhesion and more. Further technological innovations and cost reduction is likely to extend their applications to weight savings in automobiles and components for light weight engines, robots and various other machineries.
ISBN NO: 978 - 1503304048
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