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OCR for page 1
EXECUTIVE SUMMARY
The unique feature of liquid crystalline polymers (LCPs) -high local
(microscopic) orientational order, which is retained in the solid state - has
significant implications in a range of DOD applications utilizing polymers.
The remarkable mechanical properties and thermal stability of fibers from
precursor liquid crystalline solutions (lyotropic spinning dopes) are the
principal driving forces that launched these materials and encouraged efforts
to place LCPs in structural applications where weight savings are critical.
It would appear that advances in processing the lyotropic polymers could
allow the incorporation of LCPs into other than uniaxial designs multiaxially
oriented items. Moreover, novel processing might make thermotropic LCPs
eligible for critical structural applications. However, the unique feature of
LCPs is itself problematic the current understanding of processing with
control of orientation falls short of permitting deliberate manipulation of
macroscopic orientation (with the exception of unisexual fibers). Even
carefully des igned applications that exploit other features of liquid
crystallinity (an' sotropic thermal expansivity, transport anisotropy, optical
characteristics, etc.) will be retarded until there is an in-depth
understanding of how processing promotes morphology in conjunction with how
molecular structure affects the mechanical and the unusual physical properties
of these new classes of polymers.
The principal conclusions of the committee are as follows:
· New cost-ef~ective synthetic efforts and stabilization techniques are
required to manipulate and maintain sequence distribution and thereby control
polymer properties.
· Theories of LOP behavior must address polymer flexibility to
realistically predict blending, theological, and chain dynamical properties of
ordered polymer phases.
· Processing protocols must go beyond conventional methodologies, e.g.,
explore solid-state forming of LCPs in efforts to achieve multiaxial order and
obviate macroscopic heterogeneity.
1
OCR for page 2
2
· Compressive failure mechanisms must be understood in order to suggest
solutions to current mechanical limitations of LCP applications;
~of LCPs (e.g., as barrier
simultaneously, new nonstructural applications
materials) should be explored.
· LCPs may find extensive applicability in blends and composites.
However, the roles of LCPs as the dispersed phase or as the matrix phase,
filler shape and adhesion (and self-adhes~on) are complex and poorly
understood issues.
· Lowering the cost of LCP in products through lower cost monomer,
polymerization and fabrication processes will catalyze the overall acceptance
and range of applications of LCPs by the user community.
· An interdisciplinary effort is required to exploit the anisotropy of
LCPs in nonlinear optical applications.
· The current annual Federal funding level for LCP research is almost
$10 million.
· LCPs and the ir unique advantages as s tructural polymers were
discovered and developed in U.S. industrial research laboratories in the 1960s
and 1970s. A cursory glance at the following table suggests that current
research and manufacturing effort has now become worldwide.
Companies Engaged in LOP Development
United States Western Europe Japan
Allied-Signal Akzo Asahi
Amoco (Dartco) BASE Denki Kagaku
DuPont Bayer Idemitsu
Eastman DSM Kuraray
Hoechst Celanese Hoechst Mitsubishi Chemical
Monsantoi ICI Mitsubishi Gas
Montedison Mitsui Toatsu
Rhone-Poulenc Nippon Petrochemical
Polyplastics
Sumitomo
Teijin
Toray
Toyobo
Unitika
Has stopped research
Source: Outlook for Advanced Engineering Materials: Plastics, Composites and Ceramics. November
1986, R861101. Cambridge, Mass .: Arthur D. Little Decision Resources .
OCR for page 3
3
Committee discussions frequently returned to economic and geopolitical
topics, about which it was collectively agreed that members were ill-equipped
to make meaningful recommendations. Nevertheless, two of these issues deserve
attention:
· There was a consensus that meaningful evaluation of new (and
potential) LOP systems is severely hampered by a limited number of facilities
in the United States wherein intermediate-scale monomer and polymer synthesis
[between the lab-bench scale (-100 g) and pilot plant (100 to 1000 lb)] can be
carried out.
· Although many companies are market developing LCPs, large volume use
awaits lower cost polymers.
Therefore, LCPs are a fertile area warranting intensive study. The
findings will have an impact on a wide range of problems that include
mechanical and optical properties of polymers. Moreover, it is anticipated
that the findings on LCPs will lead to a more comprehensive understanding of
conventional polymers and their fabrication techniques.
OCR for page 4
Representative terms from entire chapter:
liquid crystalline
