polymer nanocomposite innovating on insulating materials

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TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING IEEJ Trans 2009; 4: 8–9 Published online in Wiley InterScience (www.interscience.wiley.com). DOI:10.1002/tee.20348 Review Paper Polymer Nanocomposite Innovating on Insulating Materials Toshikatsu Tanaka a Received 18 February 2008 1. Introduction Polymer nanocomposite was invented at the end of the 20th century. Currently, attention is being focused on this material as an innovative one, which will mark the 21st century in the field of materials science and engineering. Although originally developed as engineering plastics, this material is currently rec- ognized as very good dielectric/insulating materials, attracting original, excellent research projects. From the industrial view- point, polymer nanocomposite is attractive in that addition of a small amount of inorganic nanofiller to organic polymer will greatly alter the polymer performance. Also it is academically attractive, creating a challenge to a new, mesoscopic character- istic research of inorganic/organic boundary. 2. Polymer Nanocomposite 2.1. Formation Polymer nanocomposite is formed by (i) interlayer insertion, (ii) sol-gel, (iii) in-situ, or (iv) ultra- fine particle direct dispersion method, where a small amount of nanofiller in several wt% is uniformly dispersed in polymer. One of the figures given above for informational purposes show that an ultrafine particle direct dispersion process is used to disperse nanosilica (about 40 nm in diameter) in epoxy, the other showing the scanning electron microscope (SEM) photo of fractured surface of nanocomposite. 2.2. Dielectric/insulating characteristics After review of available data, nanocomposite has been found to have excellent characteristics with regard to permittivity, dielectric dissipation factor, low electric field conductivity, space charge, high electric field conduction, high electric field electrolumi- nescence, dielectric break-down field, treeing resistance, par- tial discharge resistance, and tracking resistance. Among these characteristics, what is remarkable is enhanced partial charge resistance for epoxy and polyimide, reduced space charge for polyethylene, and prolonged life in tree break-down V-t char- acteristics for various polymers. 2.3. Research of interfaces Nanocomposite char- acteristics result from the interface between nanofiller and poly- mer matrix. Research of interfaces advocates multicore models based on physicochemical consideration, which is accompanied by molecular dynamics simulation research. a Correspondence to: Toshikatsu Tanaka. E-mail: [email protected] Direct mixing dispersion machine Material formation SEM image: Fractured surface of nanocomposite Use mixing dispersion machine to mix nano-filler added to polymer and uniformly disperse to form nanocomposite. Nano particle: some 10 nm in particle size Bound layer: several layers Modeling Huge interface causes meso-scopic characteristics to appear Interfacial multi-core model Periodic boundary condition is entered Molecular dynamics simulation Bound layer bulk Power electronics field Bulk Bulk Basic research modeling Field of Application Electric power field Solid insulated heavy electric apparatus Source: Ttoshiba Review, December 2006 issue Toshiba Mold Transformer Catalog Merit: compact size Communications field Automotive field Courtesy of Fuji Electric Advanced Technology Co., LTD. High-density installation Expoxy casting parts 300kVA transformer Enhancement by nanocomposite technology Desired properties for next industrial insulating material 24/36kV switchgear - Thermal resistance - Mechanical strength - Fracture toughness - Insulation properties - Productivity High-density installation Utilization of high temperatures Fig. 1 Formation, property research, and application develop- ment of nanocomposite 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

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TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERINGIEEJ Trans 2009; 4: 8–9Published online in Wiley InterScience (www.interscience.wiley.com). DOI:10.1002/tee.20348

Review Paper

Polymer Nanocomposite Innovating on Insulating Materials

Toshikatsu Tanakaa

Received 18 February 2008

1. Introduction

Polymer nanocomposite was invented at the end of the 20thcentury. Currently, attention is being focused on this materialas an innovative one, which will mark the 21st century in thefield of materials science and engineering. Although originallydeveloped as engineering plastics, this material is currently rec-ognized as very good dielectric/insulating materials, attractingoriginal, excellent research projects. From the industrial view-point, polymer nanocomposite is attractive in that addition ofa small amount of inorganic nanofiller to organic polymer willgreatly alter the polymer performance. Also it is academicallyattractive, creating a challenge to a new, mesoscopic character-istic research of inorganic/organic boundary.

2. Polymer Nanocomposite

2.1. Formation Polymer nanocomposite is formedby (i) interlayer insertion, (ii) sol-gel, (iii) in-situ, or (iv) ultra-fine particle direct dispersion method, where a small amountof nanofiller in several wt% is uniformly dispersed in polymer.One of the figures given above for informational purposes showthat an ultrafine particle direct dispersion process is used todisperse nanosilica (about 40 nm in diameter) in epoxy, theother showing the scanning electron microscope (SEM) photoof fractured surface of nanocomposite.

2.2. Dielectric/insulating characteristics Afterreview of available data, nanocomposite has been found to haveexcellent characteristics with regard to permittivity, dielectricdissipation factor, low electric field conductivity, space charge,high electric field conduction, high electric field electrolumi-nescence, dielectric break-down field, treeing resistance, par-tial discharge resistance, and tracking resistance. Among thesecharacteristics, what is remarkable is enhanced partial chargeresistance for epoxy and polyimide, reduced space charge forpolyethylene, and prolonged life in tree break-down V-t char-acteristics for various polymers.

2.3. Research of interfaces Nanocomposite char-acteristics result from the interface between nanofiller and poly-mer matrix. Research of interfaces advocates multicore modelsbased on physicochemical consideration, which is accompaniedby molecular dynamics simulation research.

a Correspondence to: Toshikatsu Tanaka. E-mail: [email protected]

Direct mixing dispersion machine

Material formation

SEM image:

Fractured surface ofnanocomposite

Use mixing dispersion machine to mix nano-filler added topolymer and uniformly disperse to form nanocomposite.

Nano particle:some 10 nmin particle size

Bound layer: several layers

Modeling

Huge interface causes meso-scopiccharacteristics to appear

Interfacial multi-coremodel

Periodic boundary condition is entered

Molecular dynamicssimulation

Bound layer bulk

Power electronics field

BulkBulkBasic researchmodeling

Field of Application

Electric power field

Solid insulated heavy electric apparatus

Source: Ttoshiba Review, December 2006 issueToshiba Mold Transformer Catalog

Merit: compact size

Communications field Automotive field

Courtesy of Fuji Electric AdvancedTechnology Co., LTD.

High-density installation

Expoxy casting parts

300kVA transformerEnhancement bynanocomposite technology

Desired propertiesfor next industrialinsulating material

24/36kV switchgear

- Thermal resistance- Mechanical strength- Fracture toughness- Insulation properties- Productivity

High-density installation Utilization of high temperatures

Fig. 1 Formation, property research, and application develop-ment of nanocomposite

2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

POLYMER NANOCOMPOSITE INNOVATING ON INSULATING MATERIALS

2.4. Field of application Nanocomposite is appliedto various fields, including electric power, electronics, informa-tion technologies, and automotive industries. Figure 1 showssome examples of applications, attracting significant attentionin mold high-voltage insulation, direct current high-voltagecable, power electronics insulation, and high-density installa-tion electronic circuit fields.

3. Conclusion

As mentioned above, polymer nanocomposite is expected toplay a role as innovative insulating material in the future.

9 IEEJ Trans 4: 8–9 (2009)