Effects of halloysite nanotube orientation on crystallization and thermal stability of polypropylene nanocomposites

• Published in: Polymer degradation and stability Vol. 98; no. 9; pp. 1601 - 1608
• Main Authors: Wang, Bin, Huang, Han-Xiong
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.09.2013; Elsevier
• Subjects: Applied sciences; Composites; compression molding; cooling; Cooling rate; crystallization; Degradation; differential scanning calorimetry; Exact sciences and technology; Forms of application and semi-finished materials; halloysite; Halloysite nanotube; injection molding; Nanocomposites; Nanomaterials; Nanostructure; nanotubes; Orientation; Polymer industry, paints, wood; Polypropylene; Polypropylenes; Technology of polymers; thermal analysis; Thermal degradation; Thermal stability; thermogravimetry; volatilization; Nanocomposites; Polypropylene; Halloysite nanotube; Thermal stability; Clay; Propylene polymer; Nanotube; Crystallinity; Experimental study; Composite material; Polymer filler interaction; Compression molding; Thermal properties; Water injection; Melt crystallization; Concentration effect; Injection molding; Olefin polymer; Nanocomposite; Crystal morphology; Particle orientation
• ISSN: 0141-3910; 1873-2321
• DOI: 10.1016/j.polymdegradstab.2013.06.022

The polypropylene/halloysite nanotubes (PP/HNTs) nanocomposites were prepared via water-assisted injection molding (WAIM) and compression molding (CM). HNTs were highly oriented in WAIM parts due to the strong shear effect; whereas HNTs were randomly oriented in the CM one. The orientation of HNTs had little influence on their nucleating efficiency for the PP. However, the HNTs selectively induced α-form crystal at high cooling rates; whereas they showed β-nucleating activity at low cooling rates. Thermal analyses revealed that the HNTs delayed thermal degradation onset in the initial degradation stage, whereas they sped up the thermal degradation in the main volatilization stage at the contents of 5 and 8 wt%. The simultaneous thermogravimetric analyses and differential scanning calorimetry measurements revealed that, at a low content, the direct stabilizing effect of HNTs on PP contributed largely to the increased thermal stability of the WAIM PP/HNTs nanocomposites rather than their barrier and entrapment effect on the volatile products.