The effect of β-nucleating agent on the self-nucleation of isotactic polypropylene

In this work, the effect of beta-nucleating agent (beta-NA) on the self-nucleation of isotactic polypropylene (iPP) was systematically investigated. By comparing self-nucleation results of pure iPP and iPP containing beta-NA measured by differential scanning calorimeter, it was found that the presence of beta-NA increased the transition temperatures from Domain I to II (TI-II) and from Domain II to III (TII-III), respectively, but narrowed the temperature width of Domain II (i.e. self-nucleation Domain) of iPP. The reason for beta-NA changing self-nucleation of iPP was revealed by the combination of Fourier transform infrared, small and wide-angle X-ray scattering in-situ detecting the structure evolution of standard crystal upon heating. At the later melting stage, the remnant ordered structures including small-scale helical structure and relative-large-scale crystalline structure in iPP containing beta-NA were both more stable than that in pure iPP, which could survive at higher temperatures. The improved stability of the former structure may be related to the increases in TI-II and the later may lead to the increase in the TII-III. This improvement in thermal stability of ordered structures corresponding to different levels was closely associated to the beta-alpha transformation occurred in iPP containing beta-NA upon heating.

Automated summary

The effect of beta-nucleating agent on the self-nucleation of isotactic polypropylene was systematically investigated in this study. It was found that the presence of beta-NA increased the transition temperatures and narrowed the temperature width of the self-nucleation domain of iPP. The increased thermal stability of ordered structures in iPP containing beta-NA may be related to the beta-alpha transformation occurred upon heating.