writer：Baobao Chang, Konrad Schneider, Gert Heinrich, Yilong Li, Guoqiang Zheng(通讯作者), Liane H?u?ler,
keywords：multiwalled carbon nanotubes
source：期刊
specific source：Polymer Composites, 2018,39:E1149-E1158
Issue time：2018年

In this study, the influence of multiwalled carbon nanotubes (MWCNT) on b-isotactic polypropylene (iPP) formation in preshear injection-molded iPP/MWCNT nanocomposites is investigated layer by layer by wide angle X-ray diffraction (WAXD). WAXD results suggest

that in preshear injection-molded pure iPP, b-iPP exists in not only the shear region, but also the core region as a result of preshear-induced nucleation. The addition of MWCNT can inhibit the b-iPP formation. As the depth away from the specimen surface is decreased, the inhibiting effect is decreased. The reason responsible for that is given as follows: (1) with the addition of MWCNT, extra nuclei are induced during preshear. Both MWCNT and extra nuclei serve as a-iPP nucleation point. Therefore, the formation of b-iPP is restricted; (2) the cooling rate gradient is widely accepted to exist in the injection molded sample. A larger cooling rate at a smaller depth will give rise to a lower a-iPP crystallization onset temperature and a lower nucleation efficiency of MWCNT. Since that b-iPP grows only in the temperature range of 1058C1408C, the inhibiting effect of MWCNT on b-iPP becomes weaker as the depth is decreased.