1. INTRODUCTION Investigations into the degradation of ... - www-eng

(cont.)
Table 1
Polymers POLYESTERS POLYURETHANES SILICONES
α Cellulose Mineral Glass No filler Glass Mineral
ISO
1.35–1.40 1.70–2.20 1.20–2.00 1.20–1.40 1.21 1.88 1.88–2.8
1183
ISO
0.01–1 – 0.1–2 0.03–0.4 0.30–0.90 0.10–0.30 0.05–0.22
62
ASTM
– – 1.8–2.2 0.15 – 0.27 0.50
D325
– – 2 7 – 6 5
Properties
Specific gravity
(g/cm
3)
Water absorption
(%)
Thermal conductivity
(k cal/m.h. °C)
Thermal coefficient of expansion
(10–5/°C)
42–50 21–46 42–90 35–81 45–60 28–56 17–31
Tensile strength
(MPa)
– – 0.3–0.5 1.7–2.6 > < 3 < 3
– 9.8–19.0 4.2–12.0 2.8–4.6 3.3–8.4 14.7–17.5 8.7–15.9
ASTM
D 696
ISO
R37
ISO
R37
ISO
R37
Elongation
(%)
Tensile modulus
(GPa)
49
70
91
133
70–84 17–63 84–150 45–91 –
ISO
178
1.6–2.5 1–4 40–54 1.6–10 > 5.4 50 2
ASTM
D 256
Flexural strength
(MPa)
Impact strength
(notched) (kg cm/cm)
10 14
3 × 10 14
6 × 10 12 –10 14
2.7 × 10 14
2 × 10 15
1012–1015
> 1014
> 10
14
IEC
93
10–14 10–17 6–14 10–17 20 10–11 11–16
IEC
243
0.03–0.05 0.013–0.04 1.1–0.04 0.01–0.03 0.03–0.05 0.003–0.02 0.002–0.01
IEC
250
3.5–5.5 4.5–6.0 4.5–6.0 3.0–4.01 3.3–3.9 4.35 3.4–4.5
IEC
250
Volume resistivity
( Ω cm)
Dielectric strength
(kV/mm)
Power factor (tg)
at 10 6 Hz
Dielectric constant
at 106 Hz
– – 200 50–200 – > 450 270–450
ISO
75
Heat distortion temperature
(°C)