Dielectric Polarization Enhancement of Thermoplastic Elastomers for Sensing and Energy Harvesting Applications

Abstract

Nano-structured dielectric thermoplastic elastomers (DTEs) such as poly(styrene-co-ethylene-co-butylene-styrene) [SEBS] and poly(styrene-co-ethylene-co-butylene-styrene)-grafted-maleic anhydride[SEBS-g-MA] triblock co-polymers have been shown to have superior mechanical performances relative to conventional dielectric elastomers such as silicones because of their morphology; which comprises of continuous hard and soft block copolymers and physical cross-linking between same. However, historically their use in capacitive energy harvesting and sensing applications has been constrained by their relatively low dielectric permittivity. In this work, novel method for increasing the dielectric permittivity of DTE's while maintaining their mechanical performance by using electrically active modifiers was evaluated. Preliminary results showed a 110% and 99% increase in the dielectric permittivity, and a 787% and 300% increase in the storage modulus, of SEBS and SEBS-g-MA respectively upon addition of 10% carbon black. The storage modulus will be decreased if the materials are pre-strained. These results also indicate that relative changes in the electrical properties of polymer-additive composites is polymer-additive compatibility dependent (i.e. 1.20% decrease in the dielectric permittivity of SEBS and a 32.72% increase in the dielectric permittivity of SEBS-g-MA was observed upon addition of 10% BaTiO 3).

SEBS-Grafted Itaconic Acid as Compatibilizer for Elastomer Nanocomposites Based on BaTiO3 Particles

“…This interaction promoted the interfacial polarization and, then, increased the dielectric permittivity. Similar results have been achieved by other authors using SEBS grafted with anhydride maleic (SEBS-g-MA) [36]. Other authors have observed a similar behavior when the BaTiO3 particles are coated with dopamine and dispersed in silicone rubber [37].…”

Thermal, mechanical, dielectric, and morphological study of dielectric filler–based thermoplastic nanocomposites for electromechanical applications

“…The total dielectric permittivity of those samples was published in our previous work. 17 There was no significant difference between real dielectric permittivity shown in Figure 2 and Table 1 and total dielectric permittivity for all samples from our previous work because of low loss factor over the range of all frequency measured. However, total dielectric permittivity alone can't always give the information about the polarization capability of materials in all cases as it is the vector sum of loss factor and real dielectric permittivity.…”

“…7,16 Conductive fillers tend to change the dielectric permittivity of polymer matrices by several folds. 17 He and Tjong 18 reported the dielectric permittivity of polyvinylidene difluoride increased by 15 times with the addition 0.5% of reduced graphene sheets 19 . However, they also tend to increase the dielectric permittivity loss of nanocomposites leading such manufactured nanocomposites to have low dielectric strength.…”

Ceramic nanoparticles and carbon nanotubes reinforced thermoplastic materials for piezocapacitive sensing applications

“…The effect of ceramic particles into PVDF matrix was demonstrated in [27,28], the dielectric constant increasing with increasing filler content. Typically, the 50 wt.% of ceramic fillers is the maximum of filler for obtaining films with suitable mechanical properties [29] while maximizing the dielectric response of the composite [30]. Neat PVDF and composites having 0.15, 0.25 and 4 wt.% CNTs and 50 wt.% BT were fabricated.…”

“…With respect to SBS and SEBS, no relevant differences in the composites are observed for the addition of BT or CNT due to the fact when the CNT content is below the percolation threshold, the CNT does not form a conductive network and the nanocomposite is highly resistive, similar to BT nanocomposites. The dielectric constant increases with higher concentrations of both fillers as a result of the influence of particle distribution, polarization and interfacial polarization between the fillers and polymer matrix [30].…”