Why do iPP and PET show different behavior in phase transiti

Why do iPP and PET show different behavior in phase transitions when they are heating up in the DSC? Relate it to their molecular structure. What degree of crystallinity would you expect for a polypropylene with a degree of tacticity between that of iPP and aPP? If a given iPP sample is crystallized at a higher cooling rate that another iPP sample, which one would you expect to have better mechanical properties? Why? Does iPP crystallized under quiescent conditions have isotropic or anisotropic properties? What about iPP crystallized after the fiber pull? Explain.

Solution

1. this is due to the cross linking, IPP has less cross linking than PET so it shows up differently

2. cant say

3 this depends on the cooling curves for these samples, cant predict off hand. Only point is more crystallinity, less desirable ductility for the plastic, becomes more brittle and hard

4. must look at the data