Page 328 - Engineering Plastics Handbook

286 Engineering Plastics

175
25
500°F
260°C 150
Tensile strength, kpsi 20 420°F 125 MPa
470°F
243°C
216°C

15
300°F
149°C 100
Heat up Cool down 75
10
Cure cycle
Figure 12.23 Cure versus tensile strength.

generate water, and its creation and diffusion during this cure process
need to be managed to maintain dimensional stability and minimize
void or blister formation. As these reactions occur, virtually all mechan-
ical, chemical, and thermal properties are affected. Figures 12.23 through
12.25 show the changes that take place during the cure cycle. Strength
and elongation in the part increase dramatically until the strength is
approximately twice that of the uncured material. Uncured polyamide-
imide is brittle, as shown in Fig. 12.25, but during cure the elongation
goes from about 5% to about 15%, showing a tremendous increase in
toughness.

250
35
500°F 225
260°C
Flexural strength, kpsi 30 420°F 200 MPa
470°F
243°C
216°C

25
300°F
149°C 175
150
Heat up Cool down
20
Cure cycle
Figure 12.24 Cure versus flexural strength.