Brittle-ductile transition of impact PP blends: effect of modulus ratio of PP matrix to impact modifier

In order to quantitatively study the effect of the modulus ratio of matrix polymer to toughening modifier on the brittle-ductile transition (BDT) of the blends, the modulus ratio of polypropylene (PP) to impact modifier at various temperatures was obtained from dynamic mechanical analysis (DMA) results. The modulus ratio changed continuously from nearly 1 to more than 100 by increasing temperature from - 100 to 50 degrees C. Accordingly, the impact property of the PP/POE blends within a wide composition range was studied at various temperatures by notched impact strength test. The variations of the notched impact strength with the modulus ratio were thereby obtained for various PP/POE blends. The result shows that a clear sharp BDT appeared with increasing the modulus ratio and the critical modulus ratio is 10, that is, the modulus of impact modifier must be one tenth of that of polymer matrix in order to be effective. In addition, the effect of the microstructure on the BDT of PP/POE blends was also studied.

Automated summary

By studying the effect of the modulus ratio on the brittle-ductile transition of PP/POE blends, it was found that a clear transition occurred at a modulus ratio of 10. Additionally, the microstructure also had an impact on the BDT.