Analysis of the Scattering Power

For pure PP Q s) remains constant until the onset of yielding. The constant value for low strain is readily explained by constant contrast. After yielding sets in, the sample starts to become white. Thus the strong increase of Q s) for s 0.1 can be related to void formation. It is well-known that voids mainly affect the scattering at low s. Because Q is only a number, the isotropic scattering / (s) with 

Q = 4jt f I s)ds is prepared (cf Seet. 3.2.4) for angle-dependent inspection (Fig. 5.8). For the sample PP Fig. 5.8 shows a steep increase of scattering at very low angles (s 0.05 nm ). On the other hand, the change of the long period peak (s 0.09 nm ) is only moderate. Thus it can be concluded that the steep increase of Q with sample PP indicates considerable formation of voids as the material is strained beyond the yield. 

The blend PP-t-MMT exhibits high seattering at low s even in the unstrained state. Further increase of low-i-scattering is moderate. This means that, in eontrast to pure PP, straining of the blend does not induce an increase of voids that are small enough to be detected by SAXS. 

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