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Halloysite nanotubes as a novel β-nucleating agent for isotactic polypropylene

2009; Elsevier BV; Volume: 50; Issue: 13 Linguagem: Inglês

10.1016/j.polymer.2009.04.052

1873-2291

Mingxian Liu, Baochun Guo, Mingliang Du, Feng Chen, Demin Jia,

biodegradable polymer synthesis and properties

The nucleating ability of halloysite nanotubes (HNTs) towards isotactic polypropylene (iPP) was investigated by differential scanning calorimetry (DSC), X-ray diffraction (XRD), polarized optical microscopy (POM) and scanning electron microscopy (SEM). HNTs are identified to have dual nucleating ability for α-iPP and β-iPP under appropriate kinetics conditions. The formation of β-iPP is dependent on the HNTs loading in the iPP/HNTs composites. The composite with 20 phr of HNTs is found to have the highest content of β-iPP. Under non-isothermal crystallization the content of β-iPP increases with decreasing of the cooling rate. The maximum β-crystal content is obtained at cooling rate of 2.5 °C/min. The supermolecular structure of the β-iPP is identified as β-hedrites with flower-cup-like and axialite-like arrangements of the lamellae. Under isothermal crystallization the β-crystal can be formed in the temperature range of 115–140 °C. Outside the temperature range, no β-iPP can be observed. The content of β-crystal reaches the maximum value at crystallization temperature of 135 °C. The formation of the β-iPP in the composites is correlated to the unique surface characteristics of the HNTs.