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Polymer
Science and Engineering Introduction
Simply
stated, polymer science is the science of large molecules. By virtue
of their size alone, macromolecules have certain unique chemical and
physical properties. It is also a relatively new academic discipline
(at least in the U.S.) and one that is characterized by extraordinary
breadth. It involves aspects of organic chemistry, physical chemistry,
analytical chemistry, contemporary physics (particularly theories of
the solid state and solutions), chemical and mechanical engineering
and, most recently, electrical engineering. Moreover, there is a growing
demand for what can be called engineering technologists, those skilled
in the art of designing processes for producing specific products. Clearly,
no one person has an in-depth knowledge of all these fields. Most polymer
scientists and engineers have a broad overview of the subject that for
those doing research is supplemented by a more detailed knowledge of
a particular area. To give a flavor of what the field involves, particular
areas are discussed in the following sections.
Polymer Synthesis
Most
plastics people agree that it is unlikely that we will see any new thermoplastic
take the world by storm (i.e. achieve levels of production comparable
to polyethylene or polystyrene), but it should be kept in mind that
similar things were being said round about 1950, just before high density
polyethylene and isotactic polypropylene made their debut. This time
they may be right, however, for two very good reasons. First, all the
monomers that can be readily polymerized already have been; second,
commercializing a new commodity plastic would probably cost well in
excess of $1 billion. In any event, polymer chemists have better things
to do than bash their heads against thermoplastic walls. The action
these days is in specialty polymers or in finding new catalysts to make
commodity plastics more cheaply or with precisely defined chain structures
to give controlled properties. The types of specialty polymers that
are important include those with stiff chains and strong intermolecular
attractions to give thermal resistance and high strength, or chains
with the types of delocalized structures that result in unusual electronic
and optical properties. These materials are produced in smaller quantities
than "bulk" or commodity plastics, but are ³value added²
products that command a much higher price. The synthesis of new polymer
materials is a challenging area for anyone with an interest in organic
chemistry.
Characterization
What a chemist thinks he or she has made is not always the stuff that
is lying around the bottom of his or her test tube. Accordingly, there
is an enormous field based on analysis or characterization. This is
an intriguing and exciting area because of recent advances in instrumentation,
particularly those interfaced with high-powered yet small and relatively
cheap dedicated computers. These novel analytical techniques are not
only useful in studying new materials, but answering questions that
have intrigued polymer scientists for decades. For example, spectroscopic
techniques are used to examine local chemical structures and interactions
in polymer systems. Electron microscopy and the scattering of electromagnetic
radiation are used to characterize overall structure; how components
of a system separate into various types of phases; how chains fold into
crystals; and determining the shape of an individual chain in a particular
environment. Some techniques are so expensive that national facilities
are required, e.g. synchrotron radiation and neutron scattering, but
these are accessible to research scientists in the field. Polymer characterization
is an exciting field for those interested in the relationship of molecular
structure to macroscopic properties.
Polymer
Physical Chemistry
Paul Flory was awarded the Nobel Prize in Chemistry for his work in
this area and if you get into this subject you will come across his
name a lot. This is a subject that demands a knowledge of theory and
the ability to perform carefully controlled experiments, often using
the types of instruments mentioned above. (The area of characterization
and polymer physical chemistry overlap considerably and they are artificially
separated here merely to illustrate the different types of things polymer
scientists do). The simplest way to get a "feel" for this
subject is get a copy of Flory's book "Principles of Polymer Chemistry",
still a classic after more than forty years, and scan the chapters on
the theories of rubber elasticity, solution thermodynamics, phase behavior
etc. This subject remains intriguing, with all sorts of neat stuff in
the areas of polymer blends or alloys, polymer liquid crystals, block
copolymers, dendrimers, and so on.
Polymer
Physics
Polymer physics and polymer physical chemistry are overlapping disciplines
that are not, in many cases, easily delineated. Historically, however,
it is possible to point to an enormous impact by theoretical physicists
starting in the late 1960's and early 1970's. Until then, most theory
was based on almost classical physical chemistry, but a number of leading
physicists (notable de Gennes in France and Edwards in England) started
to apply modern theories of statistical physics to the description of
long chain molecules. The result has been a revolution in polymer theory,
one that is not easily assimilated by traditional polymer scientists,
that is still ongoing.
Polymer
physics is not confined to theory, however. Experimental polymer physics
continues to focus on areas such as chain conformation, viscoelastic
and relaxation properties, phenomena at interfaces, the kinetics of
phase changes, and electrical and piezoelectric properties.
Polymer
Engineering and Technology
Last, but by no means least, there is a vast area that is involved with
chemical engineering (the large scale chemical synthesis and processing
of polymers) mechanical engineering (studies of strength, fatigue resistance,
etc.) and engineering technology (designing a process to make a product)
applied to polymer materials. These areas are often interactive. For
example, there is enormous interest in producing ultra-high strength
polymer fibers. It turns out that even "common or garden"
polymers like polyethylene or polypropylene can be processed to give
"high-tech" materials. The trick is to align the chains as
perfectly as possible; not an easy task. Once made, of course, the mechanical
properties of these materials have to be determined. This involves more
than stretching a fiber until it breaks. The mechanical properties of
polymers are complicated by all sorts of factors (defects, relaxation
processes etc.) and the field is an intriguing combination of mechanical
measurements, structural characterization and theory.
Undergraduate
Polymer Science and Engineering Option
In
recent years, economic changes and the increasing sophistication of
polymer manufacturing technologies have created a need for skilled personnel
in the polymer manufacturing industry who understand materials processes
and can implement new technology quickly.
For
these reasons, the Polymer Science and Engineering Program offers two
"study tracks." The polymer properties track emphasizes
the traditional materials-based aspects of polymers including their
structure, properties, rheology, and processing. The polymer processing
track emphasizes polymer processing in a unique hands-on, 9-credit course
that is a mixture of lectures and lab work on production scale equipment.
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