Influence of peroxide addition on the morphology and properties of polypropylene – multiwalled carbon nanotube nanocomposites

• Published in: Composites science and technology Vol. 84; pp. 78 - 85
• Main Authors: Sathyanarayana, Shyam, Hübner, Christof, Diemert, Jan, Pötschke, Petra, Henning, Frank
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 29-07-2013; Elsevier
• Subjects: A. Carbon nanotubes; A. Nanocomposites; Applied sciences; B. Electrical properties; B. Mechanical Properties; Composites; Dispersions; Exact sciences and technology; Forms of application and semi-finished materials; Injection molding; Melts; Morphology; Peroxides; Polymer industry, paints, wood; Polymer matrix composites; Polypropylenes; Technology of polymers; Thermal properties; B. Electrical properties; A. Nanocomposites; B. Mechanical Properties; A. Carbon nanotubes; Electrical conductivity; Carbon nanotubes; Dispersion reinforced material; Composite material; Thermal stability; Compression molding; Shear viscosity; Impact strength; Olefin polymer; Percolation; Nanocomposite; Elastic modulus; Electrical properties; Double screw extruder; Propylene polymer; Mechanical properties; Experimental study; Thermal properties; Multiwalled nanotube; Morphology; Injection molding; Extrusion; Organic peroxide; Rheological properties
• ISSN: 0266-3538; 1879-1050
• DOI: 10.1016/j.compscitech.2013.05.008

The incorporation of peroxide as a reactive additive during the processing of polypropylene (PP) with multiwalled carbon nanotubes (MWCNTs) is investigated for its influence on the morphology, rheology, electrical, mechanical and thermal properties of the composites. PP is compounded with 2wt.% of MWCNT in a twin-screw extruder with screw speeds of 500 and 1100rpm. Additionally, PP modified with 1wt.% peroxide is processed at 500rpm with 1 and 2wt.% MWCNT. Morphological investigations indicate better MWCNT dispersion in the composites at considerably lower specific mechanical energy (SME) input on peroxide addition. The decrease in complex melt viscosity on peroxide addition to PP is substantially compensated in the composites by the simultaneous enhancement in MWCNT dispersion. Electrical properties of the composites shaped by compression molding show at least three orders of magnitude higher conductivity than those obtained by injection molding. To detect electrical percolation, the composite granules from the compounding process were diluted to lower MWCNT contents using a small-scale melt mixer resulting in a threshold on compression molded plates at around 0.4wt.%. Elastic modulus, tensile strength and notched impact strength of PP of the injection molded samples were slightly enhanced with MWCNT incorporation, but the effect of peroxide addition on these composite properties was rather negligible or negative. Thermal stability of PP was considerably enhanced on MWCNT addition and the composite with 1wt.% MWCNT composite on peroxide addition showed thermal stability similar to that of the 2wt.% MWCNT composite without peroxide. The finding that electrical and thermal properties achievable with 2wt.% MWCNT incorporation in a widely used polyolefin like PP could be achieved with the combined effect of 1wt.% MWCNT and peroxide at much lower SME highlights the significance of this investigation.