Establishing polymer's crystallization temperature by the self-nucleation test

Crystallizability of polymers, defined by the crystallization temperature (T-cr), can be determined using the self-nucleation effect. The temperature can be established by assuming polymer's own macromolecules to be the most effective nucleating agent. Cooling a polymer specimen in a DSC run from the self-seeding temperatures (T-s), i.e., ones contained within the domain of partial melting of the polymer, allows to determine T-cr. For isotactic polypropylene (Novolen 1100H, BASE, Germany, density 910 kg/m(3), melt flow rate 2.4 cm(3)/10 min), the temperature range corresponding to partial melting of the polymer was established by DSC (Netzsch 200) to extend from 164 degrees C to 174 degrees C. Crystallization was carried out at a cooling rate of 5 degrees C/min. The minimum crystallization temperature (T-cr,T- min) was 116.3 degrees C; the maximum T-cr,T- max was equal to 150.3 degrees C and corresponded to T-s = 163.8 degrees C.