Flow induced orientated morphology and properties of nanocomposites of polypropylene/vapor grown carbon fibers

• Published in: Composites science and technology Vol. 71; no. 2; pp. 177 - 182
• Main Authors: Larin, Boris, Lyashenko, Tatiana, Harel, Hannah, Marom, Gad
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 17.01.2011; Elsevier
• Subjects: A. Carbon nanotubes; A. Nanocomposites; Applied sciences; B. Mechanical properties; Carbon fiber reinforced plastics; Composites; Crystallization; E. Extrusion; Exact sciences and technology; Filaments; Forms of application and semi-finished materials; Isotactic; Melts; Morphology; Nanocomposites; Nanofibers; Orientated crystallization; Polymer industry, paints, wood; Polypropylenes; Technology of polymers; E. Extrusion; Orientated crystallization; B. Mechanical properties; A. Nanocomposites; A. Carbon nanotubes; Synthetic fiber; Nanofiber; Dispersion reinforced material; Mineral fiber; Composite material; Molecular orientation; Isotactic polymer; Olefin polymer; Nanocomposite; Elongational flow; Carbon fiber; Propylene polymer; Mechanical properties; Tensile property; Crystallinity; Experimental study; Hot drawing; Morphology; Concentration effect; Extrusion
• ISSN: 0266-3538; 1879-1050
• DOI: 10.1016/j.compscitech.2010.11.002

Nanocomposite filaments composed of isotactic polypropylene (iPP) and vapor grown carbon fibers (VGCF) were prepared by melt mixing extrusion, followed by melt drawing. The effect of composition and flow on the morphology was investigated by X-ray diffraction and high resolution scanning electron microscopy. Apparently in the drawn filaments, the presence of nanofibers resulted in a higher degree of orientated morphology and – as revealed by differential scanning calorimetry – higher degrees of crystallinity and crystallization kinetics enhancement. The amount of the orientated crystals increased as a result of VGCF addition, suggesting that the nanofibers obstructed the motion of polymer chains after the cessation of stretching force resulting in the delayed relaxation of stretched polymer segments. Significant stiffness improvements were observed due to the nanofibers and high draw ratios of the filaments. These results indicate that the orientated VGCF aligned in the flow direction, joined by fiber-induced crystallization of the surrounding iPP matrix, generate a strong stiffening effect.