Introduction
Experimental
Materials
Volume resistivity
-
IEC 93:1980 Methods of test for volume resistivity and surface resistivity of solid electrical insulating materials.
-
ASTM D 257-99 Standard test methods for dc resistance or conductance of insulating materials.
Dielectric properties
Results and discussion
Sample no. | Graphene content in the PU film, wt.% | Glass transition of soft segments, °C Tg1 inflection point
| Glass transition of hard segments, °C Tg2 inflection point
| Thermal properties (by TG analysis) | Mechanical properties | Surface free energy, 0.001 J m−2
| The statistical parameters of the surface roughness by AFM heighta sensor | |||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
By conventional DSC |
T
5%
|
T
max
| Ash,% |
σ
r
, MPa |
ε
r
, % |
E, MPa |
γ
S
| Surface area, μm2
|
R
a
, nm |
R
q
, nm |
R
max, nm | |||
PU-0 | 0 | −49.7 | 23.9 | 115 | 497 | 4.67 | 5.51 | 145 | 162 | 45.3 | 2500 | 28.4 | 35.2 | 361 |
PU-0.1 | 0.10 | −49.4 | 30.9 | 115 | 495 | 5.40 | 68.07 | 471 | 334 | 42.3 | 2500 | 65.7 | 94.4 | 887 |
PU-0.5 | 0.50 | – | – | 116 | 499 | 6.57 | 5.82 | 130 | 85 | 41.4 | – | – | – | – |
PU-1.0 | 1.0 | −45.2 | 32.3 | 172 | 495 | 6.80 | 38.65 | 508 | 267 | 38.7 | – | – | – | – |
PU-1.5 | 1.5 | −47.9 | 37.3 | 180 | 491 | 7.50 | 13.17 | 462 | 194 | 39.4 | – | – | – | – |
PU-2 | 2.0 | −43.4 | 38.6 | 182 | 496 | 11.24 | 58.35 | 509 | 383 | 38.4 | 2500 | 15.4 | 32.0 | 657 |
Sample no. | Multiplicity of the measurement | The measuring voltage U = 100 V | |
---|---|---|---|
Volume resistivity ρs [Ω m] | The value average value, ρs [Ω m] | ||
PU-2 | 1 | 2.6 × 105
| 3.4 × 105
|
2 | 1.0 × 105
| ||
3 | 6.6 × 105
| ||
PU-1.5 | 1 | 7.6 × 106
| 8.2 × 106
|
2 | 8.0 × 106
| ||
3 | 9.0 × 106
| ||
PU-1.0 | 1 | 8.8 × 107
| 8.9 × 107
|
2 | 8.9 × 107
| ||
3 | 9.0 × 107
| ||
PU-0.5 | 1 | 1.5 × 108
| 1.4 × 108
|
2 | 1.2 × 108
| ||
PU-0.1 | 1 | 2.3 × 108
| 2.4 × 108
|
2 | 2.2 × 108
| ||
3 | 2.8 × 108
| ||
PU-0 | 1 | 6.4 × 108
| 6.0 × 108
|
2 | 6.3 × 108
| ||
3 | 5.4 × 108
|
Sample no. |
σ
0, Ω−1 m−1
| For H-N 1 equation | For H-N 2 equation | |||
---|---|---|---|---|---|---|
PU-0 |
σ
0
| 1.01e−12 | Δε
| 8.8 | Δε
| 1.5 |
τ
| 579 |
τ
| 5.4e−3 | |||
N
| 1 |
ε
∞
| 1.07 |
ε
∞
| 1.45 | |
α
| 0.82 |
α
| 0.59 | |||
β
| 1 |
β
| 1 | |||
PU-0.1 |
σ
0
| 1.59e−12 | Δε
| 141 | Δε
| 2.2 |
τ
| 616 |
τ
| 10.6e−3 | |||
N
| 1 |
ε
∞
| 1.07 |
ε
∞
| 1.43 | |
α
| 0.84 |
α
| 0.5 | |||
β
| 1 |
β
| 1 | |||
PU-0.5 |
σ
0
| 2.49e−12 | Δε
| 1.3 | Δε
| 2.2 |
τ
| 643 |
τ
| 4.2e−3 | |||
N
| 1 |
ε
∞
| 1.30 |
ε
∞
| 1.44 | |
α | 0.86 |
α
| 0.65 | |||
β | 1 |
β
| 1 | |||
PU-1 |
σ
0
| 5.03e−12 | Δε
| 5038 | Δε
| 8.5 |
τ
| 716 |
τ
| 13e−3 | |||
N
| 1 |
ε
∞
| 1.71 |
ε
∞
| 1.45 | |
α
| 0.891 |
α
| 0.46 | |||
β
| 1 |
β
| 1 | |||
PU-1.5 |
σ
0
| 1.19e−11 | Δε
| 1e5 | Δε
| 5.5 |
τ
| 3700 |
τ
| 1.4e−3 | |||
N | 1 |
ε
∞
| 2,16 |
ε
∞
| 1.45 | |
α
| 0.91 |
α
| 0.6 | |||
β
| 1 |
β
| 1 | |||
PU-2 |
σ
0
| 4.46e−11 | Δε
| 1e5 | Δε
| 7.14 |
τ
| 3770 |
τ
| 3.3e−3 | |||
N
| 1 |
ε
∞
| 2.26 |
ε
∞
| 1.37 | |
α
| 0.912 |
α
| 0.78 | |||
β
| 1 |
β
| 1 |