Review of the Workshop Deliberations and Conclusions
The Frontiers of Polymer Processing – A Technical Overview
The objective of the examination of this issue by the breakout
groups was, of course, not to try and review in detail the technical scientific status of the
field. Rather, it was to mark in coarse brush-strokes the knowledge so far acquired, outline the
frontiers of knowledge, and identify broad areas where future research is needed. The guiding
questions were: What we know? What we know that we don’t know? What we need to know? What are the
“boundaries” of the field? Which are the relevant disciplines needed for getting ahead? And how can
polymer processing be made to be a strategic element in the chain of knowledge? The last question
was raised because several of the participants felt that the role of polymer processing was ‘taken
for granted’ without sufficient appreciation or acknowledgement resulting in lack of sufficient
funding for research in the field by the decision makers in industry and government.
There was agreement among the participants that much was
accomplished in the past decades. During this period polymer processing focused on analyzing the major
polymer processing equipment and processes (single screw extruders, twin screw extruders, injection
molding machines, blow molding machines, vacuum forming machines, calenders & roll mills, rotational
molding machines, batch and continuous mixers etc.). In doing so, the field grew and matured with the
realization that there are common phenomena in the thermo-mechanical experiences of the material in
the diverse polymer processing equipment and processes above. This realization led to the elucidation
and simulation of the detailed mechanisms and sequence of events that take place in these machines and
in the continuous and cyclic shaping processes: flow of particulate solids; principles of melting of
plastics in single screw extruders; principles of distributive, dispersive and chaotic mixing;
principles and mechanisms of devolatilization; flow of non-Newtonian polymeric melts in complex
conduits with moving surfaces using analytical, finite difference and finite element techniques;
transient developing flows into cavities; wall stress-free 1D, 2D and 3D flows as in fiber spinning,
bubble formation, and complex blow molding operations to name a few; degradation reactions in
processing equipment, etc. Not everything was elucidated to the same level and as discussed below much
remains to be done in classical polymer processing. The knowledge base developed so far was founded on,
and rooted in, several disciplines such as transport phenomena -- including fluid mechanics, heat
transfer and molecular diffusion of chemical species, non-Newtonian fluid mechanics, rheology
(continuum and to lesser extent molecular), resin thermo-physical properties and state equations,
classical mathematical techniques, and computational fluid mechanics as well as polymer physics and
thermodynamics. The focus of past research, as well as much of the current research, is on the
process and the scale of examination is the machine, with the objective of developing optimized
processes, and improved machines.
During this period, there was relative little emphasis on the
product and its microscopic and molecular structure, though there was rudimentary and semi-
quantitative treatment of what was termed ‘structuring’. Today, in some of the larger centers,
there is an important transition to a focus on the product and its properties and on the micro
and molecular scale.
Areas identified to be in need of further research on the process
side are: better understanding and advanced mathematical formulation of all the basic mechanisms
under realistic machine conditions with single polymeric feed or a mixture of them, and with the
goal of simulating the process as a whole; fundamental and multidisciplinary understanding of
melting of compacted polymer particulates under high deformation rates; much deeper understanding
of the details on how the process affects the structure on micro and molecular level; materials/
machine interactions i.e., 3D viscoelastic behavior and stability of polymeric liquids; transient
flow and non-isothermal rheology; nucleation and crystallization under stress; molecular
orientation phenomena; reaction and polymerization under flow and deformation; multiphase flows at
high rates of strains; heat, momentum, mass, entropy balances in finite domain structures of solids
and liquids, during deformation, melting and solidification; thermodynamics of interfaces; phase
transition; molecular models and modeling; connecting quantitatively structures and structure
formation at the molecular and micro scale to final properties; measurement techniques including
in-line measurements at the molecular and micro scale levels to verify theories and
predictions.
However, even the complete understanding of the above, will not
suffice to reap the full benefits imbedded in the macromolecular nature of polymeric materials
and which are inherent in the polymeric building blocks. For that a priori quantitative prediction
of product properties, made of yet non-existent chains or combination of chains of different
monomeric building blocks from basic principles, is needed.
Interesting comparisons were made to other fields such as
semiconductors which cannot be produced without a thorough knowledge at the quantum mechanics
level and fine tuned processing; multi-scale computing in solids mechanics in which microscopic
behavior is being predicted from first principles on atomic scales; drug development with computer
simulation screening of new molecules; modern catalysis and biocatalysts; and molecular biology
with potential adaptation of self-assembly properties to other fields such as biological microchips.
Science and Technology Policy Issues
This part of the breakup group discussions focused on future science
and technology policy issues. The objective was to outline future trends, and therefore, if polymer
processing has reached a turning point or crossroads, the relevant questions to ask are the
following: Is indeed the field of polymer processing and engineering transforming into a broad-based
multidisciplinary activity best described by such terms as “macromolecular engineering” or
“macromolecular technology”, or “macromolecular process engineering”? The consensus that emerged
was, first of all, that the field has reached a turning point, and second that the term
“macromolecular engineering” best captures this trend. It was stressed that this new term may also
be more attractive to students who seem to be turning away from polymer engineering, polymer
processing and even the venerable chemical engineering, but this by itself would not justify
coining a new name. The new terminology is justified only if it reflects and defines a new reality
and a desired future mission. And, this seems indeed to be the case.
Educational Considerations
Macromolecular engineering, from an educational didactic point of
view, contains the relevant molecular, macromolecular, and supramolecular sciences, design and
engineering, and process engineering disciplines. Its boundaries on the fundamental molecular level
merge with molecular biology on one hand, and the growing field of ‘complex fluids’ or ‘soft
materials’ on the other. The field of complex fluids itself is a multi- disciplinary field
encompassing chemistry, colloid chemistry, physical chemistry, physics, chemical engineering and
others. Thus, the emerging new reality seems to indicate a common core of fundamental knowledge
base for the novel macromolecular engineering, complex fluids and molecular
biology . They all deal with understanding and manipulating large molecules or complex structured fluids, which may
assume a myriad of conformations leading to profoundly varied macroscopic properties. Therefore,
it would be worthwhile to examine in detail the creation of a common curriculum to these
activities. Moreover, the discipline of chemical engineering, like polymer processing but
preceding it in time, has undergone a similar transformation. Thus, subsequent to the scientific
analysis of the industrial processes, the creation of the “unit operations” and later the
“transport phenomena” and all the chemical engineering sciences, research in the chemical
engineering discipline began to focus on the microscopic level and finally on the molecular level.
Hence, the time has possibly come to educate future engineers and scientists in all these fields
at the undergraduate level on the basis of a common core of knowledge. This common core can
branch out in the Junior or Senior and Masters level into the different specializations as
depicted in Figure 1.
Figure 1. The proposed schematic future curricular structure.
The novel discipline of molecular and supramolecular engineering and science contains the
common core of all three fields. In the Junior year, at the earliest, it branches out into
three fields: Chemical molecular engineering and science-formerly chemical engineering;
macromolecular engineering and science-formerly polymer processing and engineering, and
bio-macromolecular engineering and science-formerly biochemical engineering and
biotechnology.
The foregoing proposal blurs the distinction between
engineering and science, and this reflects the ongoing merging of science and technology
into a new indistinguishable entity4 .
4Historians of science and technology are careful to point out that
the scientific revolution that started 400 years ago and the modern technological (industrial)
revolution that started some 200 years ago were progressing in separate tracks with little contact
between them. Only on the turn of the 20th century did they begin to significantly interact and
reinforce each other. This interaction significantly increased during and after World War II, and
in the closing decades of the 20th century they fused together into an indistinguishable entity
and ignited a new scientific-technological revolution that is likely to dominate much of the 21st
century and is the ‘alma mater’ of all high technologies.
In view of the foregoing conclusions and some further
considerations and discussions on the evolution of engineering disciplines, it appears that
broadly speaking engineering disciplines in the course of the 20th century, when the sciences
began permeating them, evolved in three rather distinct stages: in the first stage the academic
research lags behind practice and focuses on applying scientific tools to understand the
prevalent “know-how” and practice in a systematic way. The tools that evolve (simple models,
methods of computation, tabulated knowledge etc.) are carried by the young trained engineers
into practice where they are easily digested. With the newly acquired tools and trained
engineers the efficiency of the processes and machines are significantly improved and thus
the practice in the field is advanced; in the second stage academic research gets ahead and
somewhat apart of practice, moving increasingly toward the fundamentals, it becomes mathematically
more sophisticated and attempts to solve, exactly, not the real but somewhat idealized problems.
The computer revolution, however, enabled academic researchers to become more fundamental and yet
deal with realistic problems. The fruits of the research could no longer be easily carried by the
graduating engineers into practice, but they had to be ‘packaged’ into computer simulation
packages. This created a division of labor between the developers of the ‘packages’ and their
somewhat ‘deskilled’ users. Finally, in the third stage the discipline goes down to the
microscopic and molecular scale, further departing from the practice, but dealing with a new
reality on the microscopic or molecular scale and often catering to a yet non-existent industry.
In this stage the ‘packaged’ tools become even more complex; usable, transparent and adaptable
“tool boxes” must be developed in order to make them applicable and practical.
The historical development of polymer processing in the past
150 years depicted in Table 1 demonstrates in general terms this evolutionary process.
Table 1. The Historical Evolution of Polymer Processing
Research Considerations
Macromolecular engineering from a research point of view is
clearly a broad-based multidisciplinary field. Consequently the research scene and practices,
in particular in academia, require restructuring. The classical “individual faculty member-graduate
student(s)” model is expected to be replaced by the large multidisciplinary team model, because
only such larger teams can be expected to conduct ground- breaking research. Such teams will
consist of several senior faculty in the needed disciplines, co-advising many graduate students
as well as trained professionals who deal with advanced instrumentation, computing, data analysis,
and literature searches. It is noteworthy that such large multidisciplinary groups already exist
and function in Europe.
From an organizational point of view, there are generally two
prevailing structural research models on the university scene: the centralized center and the
virtual one. In the former, a physical center is created where all the members of the activity
are assembled and working; whereas, in the latter each faculty member stays on in his/her host
department, and laboratories and services are dispersed but serving all members. The former is
more focused and initially more efficient, but the latter is more flexible and adaptable to change
in the long run. Moreover, in the latter faculty retains close interaction with peers in the
discipline, promotional procedures are not disturbed, and with changing research interest it is
much easier to shift to new frontiers.
The introduction of the multidisciplinary research mode to the
university campus requires many non-trivial adjustments by both management and faculty. The former
has to adapt to large-scale research themes, raise funds, interact with industry and government,
and provide infrastructure on an unprecedented scale. The faculty on the other hand have to get
used to cross departmental boundaries, learn to talk to other disciplines in a research
environment, and take the risk of sharing the fruits of research and accolades with others.
Both have to deal with the complex issues of intellectual property rights in matters of technology
transfer.
Industrial Considerations
The polymer manufacturing industry has undergone profound
restructuring in the past decade. The large polymer resin producers, who were the main
beneficiaries of the first Golden Age of polymers of the last half century, carried the brunt of
research in the 1950s, 1960s, 1970s and beyond, driven by the necessity to learn how to process
effectively a large number of emerging polymers, by globalization necessities, increasing
competition, and demand toward greater shareholder values, while setting new standards of
efficiency and benchmarks have redistributed among themselves the production of large volume
commodity and engineering polymers, driving toward larger scale of production of fewer resin
grades. Moreover, in the past two decades most of them have also significantly reduced their
erstwhile vast corporate research and central laboratories.
Yet, the US polymer manufacturing industry alone as per SPI
statistics produces $90B in sales, and the US polymer processors produce $330B in sales. The
former segment consists of a few very large companies with very substantial resources: financial,
marketing, manufacturing, and R&D resources, by highly skilled professionals from many disciplines.
The latter segment, though having appreciable higher sales, is composed in the main, of small or
medium size companies with limited financial and R&D resources. Thus, if the polymer industry is to
be involved (and it must) for both the resin manufacturers and the processors to reap the benefits
of “macromolecular engineering”, the only initial contributing participants will be the resin
manufacturers with their very substantial financial resources and still large multidisciplinary
R&D capabilities. But these large resin manufacturers have to be convinced that “macromolecular
engineering” has the realistic potential of heralding a new Golden Age for polymers, making
possible the creation of truly advanced and “customized” structures and products, with
applications that are far more demanding and in all the emerging fields of technology. If they
are convinced, then knowing that these advanced and customized macromolecular structures are highly
added-value materials, they will become involved; not alone, since the task is immense, but within
large multidisciplinary government-industry-academia structures with clearly defined missions,
short and long-term goals, deliverable and “test-beds”. The probability of this happening may at
present appear small, in view of the “mind-set” of resin manufacturers, especially the oil
companies, who are first and foremost vast volume commodity products producers (oil, gasoline
and polyolefins). Improvements and growth come through advances in catalysis and increasing
benefits of scale. On the other hand a few polymer resin producers, such as Dow and BASF, are
beginning to recognize and focus on the realization that between the large producer and the final
fabricators there may be looming an important niche of a new industrial downstream segment,
which can add great value to their commodity polymers. Parker, the Dow CEO in a recent interview
with C&E News, stated that “the company will become even more of an enabler, creating new
value-added businesses ever closer to the ultimate consumer”. Thus there may be a variety of
strategic decisions by different resin manufactures: some abandoning polymers, some
concentrating in the upstream high volume commodity polymers production, and, finally and
significantly to the growth of Modern Polymer Processing and Macromolecular Engineering, some
who see the downstream customized, value added polymer products and are willing to make the
necessary R&D and business changes. At any rate, coordinated and long-term efforts must be
mounted to actively work with industry by those who believe in the inevitability of macromolecular
engineering and its realistic potential of creating a technological renaissance enabling the
production of truly advanced and customized polymer products, which will dramatically increase the
per kilogram value of commodity polymers.
A New Government-Industry-Academia Alliance
In “macromolecular engineering”, like in all potentially highly
fruitful and promising new science-technology fields such as biotechnology and nanotechnology,
the government must take a leading role. Academia doesn’t have the means needed to support modern
very high-cost research in such fields5 , and industry in its present “mind-set” and pressed by
tight competition and shareholder demands, can only afford limited investment into long-range
generic pre-competitive, research goals. Therefore, it must be the governments through their
various agencies to provide the bulk of the resources and the driving force.
5Just consider that the cost of an advanced electron
microscope when they burst to the research scene was of the order of $25,000. Today a decent SEM
and TEM facility may easily reach many millions of dollars.
Today, and for some time now, such alliances supporting sizable
multidisciplinary groups and efforts exist in Europe. As a matter of fact, even much larger
“all encompassing” networks of excellence in this field are about to be created. On the other
hand, and in stark contrast, such alliances are still not the norm in United States, where mainly
small single investigator groups carry out research.
The Western governments in the post World War II era have been
investing huge amounts of resources in defense related basic research. The rationale was the
‘defense rationale’ driven by the superpower confrontation. Now, after the collapse of the
Soviet Union the underlying rationale of governments of free market countries is the ‘economic
rationale’, i.e. investments into future economically beneficial research efforts.
“Macromolecular engineering” clearly falls within the niche.
But, the governmental agencies too have to be persuaded that
“macromolecular engineering” is not a dressed up old-fashioned polymer engineering and science
research scene, but a quantum jump into the future and a vast potential of untapped products of
benefit to the society as a whole. They, as well as industry, have to recognize that it is an
inherent part of the broader upcoming material revolution6 . However, governments of free market
countries will “listen” more and harder to the needs and arguments of the “financial engines” of
the economy, and therefore it paramount to convince industry to support macromolecular engineering
research and development.
6Quote taken from a recent journal: “Just as the
multimedia revolution brings us into the realm of virtual reality and biotechnology opens up
the possibility of cloning, the revolution of new materials launches us into an era anything
can be man-made with infinite variety of functions. Previously designers and engineers, like
craftsmen who preceded them, chose to us a material because its main physical characteristic
was essential in order to make a particular product or archive a certain result. From now on,
the industrial reproduction of microscopic properties make it possible to design and manufacture
modular materials so that a technical requirement can be identified theoretically, and the
product specifically designed to satisfy that need can be developed ex post. Whereas traditional
materials imposed exogenous limitations on the industrial design and engineering, new materials
have become endogenous variable in the manufacturing process.”
Information Dissemination Considerations
The dissemination of knowledge in the field of polymer processing,
engineering and science is covered by a large number of professional journals with many of
them enjoying a relatively limited readership. There are fewer specialized journals devoted to
polymer processing and engineering by contrast to pure polymer science. Appendix G contains a
list of polymer related journals and their impact factors under the categories of
“Chemical Engineering” (8 out of 117) and “Polymer Science” (total 69). The turning point that
we have reached would require the editorial boards of these journals to reevaluate their policies.
They must in an appropriate way reflect the unfolding multidisciplinary nature of the field.
This could be done, for example, by widening the scope of the publication, by providing the readers
on a regular basis with review articles on neighboring relevant fields, by providing abstracts of
important papers in these fields and by other similar means; by streamlining the journals “picture”
(too many, too fragmented, too small and limited journals competing with each other) into fewer and
larger journals; wider and more coordinated use of the Internet; establishing sessions on
“macromolecular engineering” and issues allied to it during national and international meetings;
continuous stream of articles to technological and trade journals to ignite the imagination of the
processing segment of the industry.
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