High Performance Nanocomposites for Mechanical Application: Design, Preparation and Characterization

NANOTECHITALY2012

High Performance Nanocomposites for Mechanical Application: Design, Preparation and Characterization

A. Passalacqua (1), A. Ballestrazzi (2), S. Benuzzi (2), S. Valeri (2,3), J. M. Kenny (4), L. Torre (4), A. Iannoni (4), A.

Terenzi (4) (1) Centro Interdipartimentale InterMech-MO.RE, University of Modena e Reggio Emilia, Via Vignolese 905/b - 41125

Modena, Italy (2) Department of Physics, University di Modena e Reggio Emilia, Via Campi 213/A, 41125 Modena, Italy

(3) CNR - Istituto Nanoscienze - Centro S3 Via Campi 213/A, 41125 Modena, Italy (4) University of Perugia, Strada di Pentima 4, 05100 Terni (TR) Italy

Introduction and aim Nowadays, there is an increasing demand of new high performance materials in terms of enhancement mechanical and tribological properties in order to meet the severe conditions required in some different application areas as aerospace and defence, industrial machinery, automotive, oil and gas, as well as medical implant technology. In this context, polymeric nanocomposites represent new possibilities for innovative product development in the future. Nanoparticle incorporation may lead to composite materials with superior mechanical and tribological properties like modulus, strength and toughness, and especially wear resistance and friction reduction [1-3]. In this context, their further development and characterization are one of the main goals of synergistic cooperation between the Sup&rman laboratory of University of Modena e Reggio Emilia (Italy) and the STM laboratory of University of Perugia (Italy). Among the different scientific activities of Sup&rman laboratory, it is worth to note the ones related to the understanding of tribology principles of polymeric nanocomposities: (i) development of innovative methodologies for testing tribosystems under special environment, operating conditions and geometric contact to mime several industrial applications by means of tribological testing, taking into account a wide range of loads, speeds, lubricants and temperatures. (ii) monitoring and controlling the wear phenomena that is critical for an effective design strategy. In particular, the wear mechanism is studied using both chemical and physical analytical tools, such as infrared spectroscopy based on Fourier transform (FT-IR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM) and profilometry (Fig. 1). As far as STM activities in the field of nanocomposities are concerned, they can be schematized as follows: (i) development and production of engineered nanopolymers aimed to improve the performance of different matrices used in several application field, such as automotive, aerospace, commodities and packaging. (ii) analysis and optimization of the different parameters which characterise the dispersion of nanoparticle into the

polymer during the injection moulding process in order to increase some of the properties of the final composite. (iii) study of mechanical, dynamic-mechanical and rheological properties of materials, by means of tension and compression test, ball-drop impact test, dynamic mechanical thermal analysis (DMTA) and rotational viscometers (RV).

Fig. 1: Wear track characterization by means of (a) FTIR spectra, (b) SEM image, (c) AFM profile and (d) 3d Profile To effectively design polymer nanocomposites for industrial applications, it is necessary to understand the effects of nanoparticles on final proprieties of the polymers. In this project, systematic studies are carried out on the variability of the structural and mechanical properties as function of the different used nanofiller. Furthermore, the overall mission is to find a correlation between the structural and mechanical changes with the tribological proprieties of thermoplastic nanocomposite due to the inclusion of nanoparticle. This will allow to design nanocomposite materials by selecting ad hoc nanofillers in order to increase their efficiency for mechanical engineering and metal replacement applications. Experimental and discussion In this study, a PEEK matrix has been used as ideal high-performance materials for mechanical and tribological applications to fabricate nanocomposite incorporating nano-sized Al2O3, hexagonal-BN, SiO2 and Wollastonite [4-6]. The samples are produced by a micro compounder

NANOTECHITALY2012

extruder coupled with micro an injection moulding machine. The obtained injection moulded samples were then chemically and physically characterized to study the effects of material composition on the properties of the final products.

Fig. 2: (a) Micro compounder extruder, (b) micro injection moulding machine, (c) moulded polymeric disc and (d) tensile test specimens. In particular, their crystallinity degree has been studied with differential scanning calorimetry (DSC), X-ray diffraction (XRD) and FT-IR techniques following the work of Chalmers in 1984 [7]. Furthermore, their mechanical properties have been studied by means of tensile test in standard condition and at high temperatures, 130 °C, just below the glass transition. The friction and wear studies were carried out by sliding a 100Cr6 steel ball with a diameter of 4 mm against the nanopolymer discs using CETR UMT-2 tribometer (Fig. 3). Two constant normal loads (5 and 10 N), two temperature conditions (25° and 130°) and a linear speed of 2 ms-1 were applied on the samples during the tribological tests running for 1 hour. The wear rate has been evaluated by using a stylus profilometer.

Fig.3 The schematic drawing of the ball-on-disc test.

The worn surfaces of the sample were investigated by SEM to examine the potential tribological damage mechanisms. The results have provided useful and important information about the influence of the studied nanofillers on the level of cristallinity of PEEK nanocomposites and their influence on mechanical and tribological properties. The reached conclusions could have interesting industrial implications in nanocomposite design.

References [1] S. Komarneni, “Nanocomposites”, Journal of Materials Chemistry, 2, 1219-1230, 1992. [2] R. Roy, “Purposive design of nanocomposites: entire class of new materials,” Materials Science Research, 21, 25-32 1986. [3] K. Friedrich, and A.K. Schlarb, “Tribology of Polymeric Nanocomposites” Elsevier 2008 [4] A. M. Díez-Pascual, M. Naffakh, C. Marco, G. Ellis, M. A. Gómez-Fatou, " High-performance nanocomposites based on polyetherketones", Progress in Materials Science 57, 1106–1190, 2012 [5] G. Zhang, A.K. Schlarb, S. Tria, and O. Elkedim, “Tensile and tribological behaviors of PEEK/nano-SiO2 composites compounded using a ball milling technique” Composites Science and Technology, 68, 3073-3080, 2008 [6] J. Tharajak, T. Palathai and N. Sombatsompop, "Tribological Properties of Flame Sprayed Hexagonal Boron Nitride/Polyetheretherketone Coatings" Advanced Materials Research, 410, 333-336, 2012 [7] J. M. Chalmers, W. F. Gaskin and M. W. Mackenzie “Crystallinity in poly(aryl-ether-ketone) plaques studied by multiple internal reflection spectroscopy”, Polymer Bulletin, 433-435, 1984 Biosketch Alessio Passalacqua received the Master and Ph.D. degrees in Chemistry from the University of Modena e Reggio Emilia, Italy, in 2002 and 2007, respectively. He has currently a research fellow of Interdipartimental Center for services and applied research in high mechanics and motoring InterMech-MO.RE, University of Modena e Reggio Emilia. His current research interests include the design and characterization of polymer-based composites and nanocomposites with the aim of improving their mechanical, tribological, electrical-magnetic, and chemical-physical properties. Contacts Alessio Passalacqua, Department of Physics, University di Modena e Reggio Emilia, Via Campi 213/A, 41125 Modena, Italy Phone: (+39) 059 205 5729 Email: [email protected]