Page 181 - Handbook of Plastics Technologies

THERMOSETS

THERMOSETS 3.51

TABLE 3.49 Skybond Polyimide Laminates
Flexural modulus, kpsi 3,120
335 hr/299°C 3,120
Flexural strength, kpsi 80
30 min/407°C 53
Tensile strength, kpsi 57
335 hr/299°C 42
Volume resistivity, Ω-cm 2.47 × 10 15
Dielectric constant 4.15
Dissipation factor 0.00445
Dilectric strength, V/mil 179
Water absorption, % 0.7

TABLE 3.50 Silicone Polyimide
Electrical Properties
17
Bulk resistivity 10 Ω-cm
Dielectric constant 3.0
Dielectric strength 5.5 MV/cm

FIGURE 3.44 General Electric silicone polyimides.

200 to 250°C, followed by oven post-cure 12 to 24 hr to complete the cross-linking reac-
tion. This produces excellent mechanical properties and heat resistance (Table 3.51).
3.1.6.3.2 Acetylene-Terminated Imide Oligomers. Oligomers containing finished im-
ide groups can be synthesized with terminal acetylenic (ethynyl) groups (Fig. 3.46). When
these are impregnated into reinforcing fabrics and heat-cured, for example 500 hr/288 to

FIGURE 3.45 Bis-maleimides.

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