Page 211 - Engineering Plastics Handbook

184 Engineering Plastics

T and HDT versus PPE/PS levels
g
220
200 T g
HDT @ 1.84 MPa
°C 180
Temperature, 160

140
120
100

80
0 20 40 60 80 100
Weight, % PPE
Figure 9.2 Effect of PPE on T g and HDT.

However, other properties such as flexural modulus and strength, ten-
sile strength, and notched Izod impact strength exhibit a synergistic
behavior (positive nonlinear combination) wherein the properties are
better than those predicted by linear behavior. The data appear in Fig. 9.3
[17, 18]. Such behavior suggests increased attractive energy between PPE
and PS polymer chains.
Modified PPE resins tend to assume the best features of PPE and poly-
styrene [19, 20]. For example:

Strength and modulus versus PPE/PS levels
460

Flexural modulus
20 440

Strength, kpsi 15 420 Flexural modulus, kpsi

400

10
Flexural strength 380
Tensile strength

5 360
0 20 40 60 80 100
Weight % PPE
Figure 9.3 Effect of PPE on strength and modulus.