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Supporting electronic information (ESI) file for publication

Thermoplastic elastomer nanocomposites with controlled nanoparticles dispersion for HV

insulation: correlation between rheological, thermal, electrical and dielectric properties

E. Helal1, E. David

1, M. Fréchette

2 and N.R. Demarquette

1*

1Mechanical Engineering Department, École de Technologie Supérieure, Montréal, QC, Canada

2Institut de Recherche d’Hydro-Québec, Varennes, QC, Canada

* Corresponding author: Nicole R. Demarquette, Department of Mechanical Engineering, École de Technologie

Supérieure, 1100 rue Notre Dame Ouest, H3C 1K3 Montreal, Canada.

E-mail: NicoleR.Demarquette@etsmtl.ca, Phone: (001) 514 396-8658

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Annex I. Particle size analysis and size distribution of ZnO nanoparticles in to SEBS-MA-5

nanocomposite

A TEM image of low magnification was selected to investigate the size distribution of ZnO

nanoparticles/small agglomerations as dispersed in the nanocomposite. Initially, several processing steps

were performed with the software to isolate the particles. Then, the particle size analysis was performed

automatically as indicated in Figure S1. In particular, 504 particles were considered for the analysis and

the particle size was determined based on Feret’s diameter (given directly by the software).

Based on the analysis, ZnO particles/agglomerations were classified in 12 classes of dimensions ranging

from 0 to 220 nm as reported in Figure S2. This size distribution reveals that more than 60 % of ZnO

particles/agglomerations, as dispersed in SEBS-MA, have sizes between 20 and 60 nm. This fact

confirms the achievement of nanoscale dispersion.

Figure S1: Steps of particle size analysis: (a) TEM image considered for the analysis (related to SEBS-MA-5

nanocomposite, (b) cropped image, (c) particle domains isolated, (d) analyzed domains

(a) (b)

(c) (d)

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Figure S2: Size distribution of ZnO nanoparticles/agglomerations in SEBS-MA-5 nanocomposite based on

particle size analysis

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Annex II. TEM images corresponding to SEBS-MA-5 nanocomposite (sample stained with RuO4)

The TEM images corresponding to SEBS-MA-5 stained sample, reported in Figure S3, indicate the dominance of

cylindrical morphology. Unfortunately, the location of nanoparticles is not clear due to a potential undesirable

interaction between RuO4 with the zinc element. Many black spots, of size considerably larger than the average

nanoparticles size, were observed throughout the treated sample in TEM micrographs. They correspond to the

regions where ZnO reacted with the staining agent.

Figure S3. TEM images corresponding to SEBS-MA-5 nanocomposite after staining with RuO4 (black spots

correspond to regions where ZnO reacted with the staining agent)

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Annex III. Imaginary permittivity as functions of frequency and temperature of SEBS-1 and SEBS-

MA-1 nanocomposites

Dielectric loss spectra corresponding to SEBS-1 and SEBS-MA-1 nanocomposites are reported

respectively in Figure S4(a) and Figure S4(b). The measurements were performed at different

temperatures ranging from 25 to 105 °C.

(a)

(b)

Figure S4. Imaginary permittivity, ɛ’’, as functions of frequency and temperature corresponding to: (a) SEBS-1

and (b) SEBS-MA-1 nanocomposites

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Annex IV. Effect of drying on dielectric response of SEBS-MA-5 nanocomposite

Dielectric loss spectra corresponding to SEBS-MA-5 nanocomposite before and after drying are

reported respectively in Figure S5(a) and Figure S5(b). The measurements were performed at different

temperatures ranging from 20 to 110 °C. Only a marginal effect could be observed.

(a)

(b)

Figure S5. . Imaginary permittivity of SEBS-MA-5 nanocomposite: (a) before drying and (b) after drying

for 3 days at 65°C under vacuum

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Annex V. Effect of drying on the dielectric response of SEBS-MA-20 nanocomposite

Dielectric loss spectra corresponding to SEBS-MA-20 nanocomposite before and after drying are

reported respectively in Figure S6(a) and Figure S6(b). The measurements were performed at different

temperatures ranging from 20 to 110 °C. Only a small effect could be observed at low temperatures

(Figure S6(c)).

(a) (b)

.

(c)

Figure S6. . Imaginary permittivity of SEBS-MA-20 nanocomposite: (a) before drying, (b) after drying for

3 days at 65°C under vacuum and (c) comparison at selected temperatures

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Annex VI. Effect of drying on the dielectric response of SEBS-20 nanocomposite

Dielectric loss spectra corresponding to SEBS-20 nanocomposite before and after drying are reported

respectively in Figure S7(a) and Figure S7(b). The measurements were performed at different

temperatures ranging from 20 to 110 °C. Several changes were obseved, mainly the increase of dielectric

losses at low frequencies after drying (Figure S7(c)).

(a) (b)

(c)

Figure S7. . Imaginary permittivity of SEBS-20 nanocomposite: (a) before drying, (b) after drying for 3

days at 65°C under vacuum and (c) comparison at selected temperatures

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Annex VII. Mapping of eroded area

Mappings of the eroded area corresponding to neat materials and nanocomposites containing 1wt% ZnO are

reported in Figure S8. To evaluate the performance of SEBS-MA-ZnO compared to SEBS-ZnO in terms of

resistance to erosion, the erosion depth (estimated from the mapping) might be considered as a quantitative

parameter. For instance, the maximum depth of erosion in neat SEBS is around 177 µm (Figure S8(a)) while it is

reduced to 128 µm in SEBS-1 nanocomposite (Figure S8(c)). In unfilled SEBS-MA, the estimated erosion depth

is equal to 145 µm (Figure S8(b)). It was reduced to only 38 µm in SEBS-MA-1 nanocomposite (Figure S8(d)).

(a) (b)

(c) (d)

Figure S8. Mapping of eroded area in different SEBS-ZnO vs. SEBS-MA-ZnO samples: (a) SEBS, (b) SEBS-

MA, (c) SEBS-1 and (d) SEBS-MA-1

Distribution

of erosion

depth