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| Material design of high-performance
polymers by applied rheology |
Rheology, the science of flow and deformation,
is indispensable for research on materials showing complicated mechanical responses, such as polymers.
Further, rheological properties can be employed as a powerful tool to characterize the structure of soft materials.
This is why R&D sections of companies require specialists in the field of rheology.
Since rheology is a practical science,
the materials used as research subjects are wide-ranging-they include
plastic, fiber, rubber, paint, food, cosmetics, bio-materials and nanocomposites.
Expertise and technology in this area are also needed in the processing operation of polymeric materials into
final products.
Our laboratory is designing new polymers based on the rheological information.
In particular, we are carrying out the
research activities outlined below.
1. Research and Development of High-Performance and Functional Polymers
2. Study on Polymer Processing
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Director
Masayuki Yamaguchi, Dr. Professor |
| [E-mail] |
m_yama@jaist.ac.jp |
| [Phone] |
+81-761-51-1621 |
| [Facsimile] |
+81-761-51-1625 |
| [Degrees] |
B.E. (1987), M.E. (1989), Doctor degree (1999)
from Kyoto University |
| [Business career] |
TOSOH Corporation (1989-2005)
* New Jersey Institute of Technology / Polymer Processing Institute
(2000-2002)
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Shogo Nobukawa, Dr. Assistant Professor |
| [E-mail] |
nobukawa@jaist.ac.jp |
| [Phone] |
+81-761-51-1626 |
| [Facsimile] |
+81-761-51-1625 |
| [Degrees] |
B.E. (2006), M.E. (2008), Doctor degree (2011)
from Osaka University |
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| [1] |
Research and Development of high-performance polymers and functional polymers |
| High-performance poly(lactic acid) |
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Material design of high-performance polymers and functional polymers is demonstrated by means of rheological modification.
The target polymers include newly developed polymers, biomass-based polymers, and conventional polymers.
A large amount of poly(lactic acid) (PLA),
as one of the biomass-based plastics, will be produced in near future.
However, the mechanical properties and processability should be improved
for wide application. We are developing
(1) a new method to improve heat resistant property by nanofibers (Fig.1),
(2) a novel molecular composite with newly developed nucleating agent (Fig.2),
(3) flexible PLA and shape-memory PLA (Fig.3), and
(4) novel PLA showing good processability at various processing operations.
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The material can be deformed with no difficulty in a hot water and
kept the shape after cooling.
When heated up, it recovers the original shape.
| High-performance poly(3-hydroxybutyrate) |
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| Poly(3-hydroxybutyrate) (PHB) is produced by microbes and
thus shows extraordinary biodegradable property. Further,
PHB shows high melting point and excellent rigidity,
which are comparable with those of polypropylene.
In order to improve the poor properties of PHB, the following projects are carried out.
(1) Rheology control to be available for various processing operations.
(2) Enhancement of mechanical properties such as impact strength. (Fig.4)
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| Development of optical-functional film by cellulose ester
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| High-performance optical films whose birefringence is highly controlled
are developed by means of molecular composite technique for cellulose ester.
In particular, we succeeded to design a new extruded film showing unique dispersion property
of birefringence. This property is desired for a long time in order to develop
a thin and high const-performance LCD display. |
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Fig.5 Wavelength dispersion of orientation birefringence for a new film (red cirlces).
The values are almost identical to the ideal ones (blue line).
| Improvement of processability and mechanical properties for recycled PET |
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| Molecular weight of recycled poly(ethylene terephthalate) (PET)
is quite low in general. Therefore, mechanical toughness
in a solid state and melt elasticity in a molten state are poor.
The purpose of this project is to improve the melt elasticity
by adding a small amount of reactive modifier. Further,
nano-scale rubbers are dispersed homogeneously to improve the mechanical toughness |
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| High-performance Polypropylene by precise control of molecular orientation |
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| Transparent polypropylene (PP) is being developed by high level of molecular orientation.
Further, the new technology,
which makes it possible to produce transparent PP at low-temperature processing,
is proposed considering the complicated structure of injection-molded products.
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Moreover, a new method to obtain the products having anomalous molecular orientation is proposed.
In this method, hybrid technique of a new type of nucleating agents and precise control of processing condition
makes it possible to obtain the material
in which PP molecules orient perpendicular to the flow direction.
Since the technique enables to control the direction of the crack propagation,
the products will be useful for automobile parts, food packagings, and so on.
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| Material design of conductive polymers with carbon nanotubes |
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| This is a technology to provide conductive nature by carbon nanotubes (CNT).
Manipulated technique to localize the CNT in a polymer nanocomposite is established
by "CNT transfer" behavior from one polymer to another. Because only a tiny amount of CNT is required for
conductive nature, the cost-performance should be improved greatly. |
| Development of new engineering plastics with anti-abrasion property |
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| Modified poly(tetrafluoroethylene) (PTFE) is finely dispersed
in a polyamide with reactive blending technique.
Morphology control is performed with a technique of processing operations
such as extrusion and injection-molding. The obtained materials show excellent
anti-abrasion property, mechanical property, and good processability. |
| Molecular design of self-repairing polymer |
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| New concept of a self-repairing material is proposed
using a topological interaction of dangling chains in a network polymer.
As an intelligent and biomimetic material, it will be applied in various products.
The effect of primary molecular structure on the processing failures is also investigated.
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The Japan Journal, Vol.4, 27 (2007).
| Material design of high performance PMMA |
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Poly(methyl methacrylate) (PMMA) shows excellent transparency,
and thus is employed for various optical applications.
We are developing a new type of PMMA composite having enhanced mechanical toughness
without losing excellent transparency
by means of molecular composite and control of molecular orientation.
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Study on Polymer Processing |
| Extrusion coating of polyolefins |
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Rheology provides fundamental information on polymer processing.
Based on the experiences and basic information on polymer sciences,
extensive study on various processing operations such as foaming, injection-molding
and extrusion are carried out considering the properties of final products.
The obtained results provide
new ideas for material design of high-performance or functional polymers.
Extrusion coating is performed at considerably high temperature
to enhance the adhesive property with a substrate.
We are proposing a material design for extrusion coating
considering the rheological change during the processing,
such as shear modification and thermal degradation.
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| Foaming of linear polymers |
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Because of the weak melt elasticity,
foaming of linear polymers, such as polypropylene (PP) and poly(lactic acid) PLA,
is difficult in general
in spite of the intensive needs in various applications
such as automobile parts and food tray. We are proposing various techniques
to enhance the strain-hardening in elongational viscosity,
one of the most important elastic natures for foaming, such as critical gel method,
blending of flexible nanofibers, and incorporation of long-chain branches.
The final target of this project is to obtain foamable PP and PLA without crosslinking procedure,
which enables to material recycling.
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| Effect of applied flow history on the rheological properties and processability |
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| Rheological properties and thus the processability
of long-chain branched polymers are sensitive to the processing history,
because long-chain branches align to the flow direction under shear dominant flow.
Considering the phenomenon, called "shear modification", screw geometry and
material recycling have to be decided. This project deals with the unique phenomenon
from the view points of molecular rheology.
Further, industrial application is proposed. |
Fig.11 Growth curves of uniaxial elongational viscosities at various strain rates for autoclave LDPE
having different processing histories.
YAMAGUCHI Laboratoty
School of Materials Science, JAPAN ADVANCED
INSTITUTE OF SCIENCE AND TECHNOLOGY
Address: 1-1, Asahidai, Nomi, Ishikawa 923-1292 Japan
phone：+81-761-51-1621 facsimile：+81-761-51-1625 E-mail：m_yama@jaist.ac.jp |
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