**9. References**

396 Thermoplastic Elastomers

This increase is due to the fact that the OMMT clay behaves as a reinforcing agent for the

**EPDM-g-MA**

**EPDM-g-MA/OMMT/PP-g-MA**

**EPDM-g-MA**

**EPDM-g-MA/OMMT/PP-g-MA**

The results confirm that the ionic thermoplastic elastomers based on EPDM-g-MA have properties similar to EPDM-based vulcanized rubber blends, and in addition, they can be easily processed using methods specific for thermoplastic materials, thus removing the vulcanization stage involving high power expenditure and release of noxious compounds determining improved characteristics (higher values for elasticity, ageing resistance,

Ionic thermoplastic elastomer granules can be used in various areas, due to specific properties such as resistance to water and diluted or concentrated acid and base solutions,

resistance to accelerated aging, abrasion resistance or resistance to repeated bending.

abrasive resistance, acid and alkali fastness) of the resulting materials.

Fig. 32. Effect of nanoclay loading on elongation at break

Fig. 33. Tear strength as a function of nanoclay content

polymer matrix leading to the enhanced hardness.

**8. Conclusions** 


**1. Introduction** 

superior actuation properties than others.

reversible process.

**19** 

Chong Min Koo

*South Korea* 

**Electroactive Thermoplastic** 

*Korea Institute of Science and Technology & University of Science and Technology* 

 **Dielectric Elastomers as a New** 

 **Generation Polymer Actuators** 

Actuators or transducers, represent devices that directly convert electrical energy to mechanical energy and thus generate a force and motion. The fast growing industries of highly integrated electronics, medicals, and robotics, eagerly demand new types of transducers with flexibility, high energy efficiency and compactness, because conventional actuators including pneumatic actuators, motors, and hydraulic cylinders, have many restrictions such as heavy weight, rigidity, restrictive shape, complex transmission, and limited size. Electroactive dielectric elastomers have garnered much more attention as promising alternative candidates for next generation compact actuators or transducers than other electroactive materials such as electroactive ceramics, shape memory alloys, and even other electroactive polymers like conductive polymers and ionic polymer metal composites, owing to their attractive properties such as large electromechanical strain, fast response, high power to mass ratio, softness, facile proccessibility, and affordability (Pelrine et al. 2000a, 2000b; Shankar et al., 2007a, 2007b). For example, a comparison of the properties of electroactive dielectric elastomers and other widely used transducer materials lists in Table 1. Piezoelectric materials have quite fast and high energy efficient response, but produce a limited strain (Furukawa & Seo, 1990). Shape memory alloys (Lagoudas, 2008), conducting polymers (Bay et al., 2004) and ionic polymer metal composites (Nemat-Nasser & Wu, 2003) are capable of producing relatively large strain, but they suffer pretty slow response and poor coupling efficiency. In contrast, the electroactive dielectric elastomers have much

A dielectric elastomer film is compressed electrostrictively in the longitudinal direction, and spreads in the transverse planar direction, as an electric field is applied across dielectric film thickness throughout the electrodes, illustrated in Figure 1. A dielectric elastomer film is coated with compliant conductive electrodes such as carbon grease and silver grease. When the external electric field is removed, the film is recovered to original shape owing to its shape memory property. That is to say, the electric actuation of the dielectric elastomer is a

