Zum tribologischen Verhalten neuartiger, funktionalisierter "Epoxy-Carbon-Nanotube-Composites"
Final Report Abstract
Carbon nanotubes (CNT) are known for their supreme mechanical properties, electrical and thermal conductivity. To combine the advantages of CNT with the benefits of epoxy resin such as high chemical resistance, easy processability and other, CNT have been incorporated in epoxy resin to obtain multifunctional nanocomposites. The objectives of the study are to investigate the effect of the incorporation of CNT in epoxy matrix, the influence of the volume (weight) fraction of CNT and CNT surface modification on the tribological properties and contact surface temperature of the nanocomposites during sliding at different conditions to understand the wear behaviour of CNT-epoxy nanocomposites. Surface modification of carbon nanotubes has been performed using non-covalent aminofunctionalization of carbon nanotubes using melanine. The dispersion of pristine CNT and surface modified CNT was carried out using three-roll mill (calandering). The simulttaneous evaluation of triblogical properties and surface temperature was carried out using the test rig based on the pin-on-disk and IR sensor, respectively. The advantages of the application of CNT in epoxy matrix for developing nanocomposites with improved tribological characteristics and thermal conductivity while exhibiting the electrical conductivity have been demonstrated. The effect of the sliding conditions has been evaluated. The formation of the transfer film on the counter body surface has been indicated by SEM with the application of EDX and by White light profillometry (WLP). The CNT distribution, evaluated by SEM analysis of the cryogenic surface fracture, demonstrated the benefit of surface modification of CNTs. DMTA showed an improvement of the storage modulus. The application of surface amino-modification has shown an improvement in the mechanical properties such as storage modulus that was demonstrated by DMTA. The electrical conductivity was observed for the nanocomposites with the CNT content higher than 1 wt-%. It is demonstrated that with increasing the CNT content and with the application of surface modification the contact surface temperature, the coefficient of friction and specific wear rate decrease. A decrease in the contact surface temperature agrees with increasing of the thermal conductivity at higher CNT content and with enhanced heat transfer along pin specimens with increasing the CNT content simulated by the Finite Element Analysis using ANSYS. Two periods of the alterations in properties can be distinguished. The cyclic character of the temperature and coefficient of friction profiles versus time during sliding has been stated. With increasing pressure and sliding speed the contact surface temperature, the coefficient of friction and the wear rate increase. With increasing pressure and sliding speed, the amount of the transferred nanomaterial on the counter body surface increase. The wear tracks on the worn pin contact surface observed by SEM with the application of EDX and by WLP have different profiles depending on the sliding conditions. The incorporation of CNT in epoxy, increasing the CNT content and the application of surface modification to CNT the contact surface temperature decrease, the tribological and mechanical properties of the nanocomposites improve while providing the electrical conductivity at the CNT content exceeding 1 wt-%. The improvement in the tribological properties is accompanied by enhanced heat transfer with increasing the CNT content in epoxy nanocomposites. The incorporation of carbon nanotubes in epoxy resin leads to the possibility to create multifunctional nanocomposites with improved triobological properties, enhanced thermal and electrical conductivity. The characteristics of such advanced nanocomposites are based on the beneficial properties of carbon nanotubes while maintaining good chemical resistance and easy processability provided by epoxy resin. Future research can be focused on improving the carbon nanotube distribution in polymer matrix while providing good electrical and thermal conductivity. Additional benefits can be brought by the application of other nanoand microfillers simultaneously with CNT. To improve the properties of the multifunctional nanocomposites, it is of interest to investigate the possibility to incorporate short carbon fibers or spherical inorganic nanoparticles such as titanium dioxide in epoxy matrix in addition to carbon nanotubes. The results can contribute to further development of multifunctional nanocomposites with enhanced wear resistance.
Publications
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Functionalisation of multi-walled carbon nanotubes (MWCNT) using 1,3,5-triazine: Characterization of thermal stability and chemical structure and effect of thermal properties of epoxy resins. 2008 European Material Research Society Fall. Warshaw, Poland (2008)
L.A.S.A. Prado, A. De la Vega, J. Sumfleth, K. Schulte
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Contact surface temperature and tribological characteristics during sliding wear of CNT-epoxy nanocomposites. Carbon Nano Tube (CNT) – Composites 4th International Conference on Carbon Based Nanocomposites. Hamburg, Germany (2009)
I.J. Zvonkina, A.K. Schlarb, L.A.S.A. Prado, K. Schulte
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Contact temperature and wear rate of CNT-epoxy composites in the dry sliding wear process. Workshop on Contact Mechanics and Friction. Berlin, Germany (2009)
I.J. Zvonkina, A.K. Schlarb
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Non-covalent functionalisation of multi-walled and double-walled carbon nanotubes using melamine. Carbon Nano Tube (CNT) – Composites 4th International Conference on Carbon Based Nanocomposites. Hamburg, Germany (2009)
L.A.S.A. Prado, A. De la Vega, J. Sumfleth, K. Schulte
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Non-covalent functionalisation of multi-walled and double-walled carbon nanotubes: Positive effect of the filler functionalisation on high glass-transition temperature epoxy resins. Journal of Polymer Science Part B: Polymer Physics Edition 47 (2009) 1860-1868
L.A.S.A. Prado, A. De la Vega, J. Sumfleth and K. Schulte
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Contact surface temperature of CNT-epoxy nanocomposites during sliding wear. Journal of Plastics Technology 1-2 (2010) 33-49
I.J. Zvonkina, A.K. Schlarb, L.A.S.A. Prado and K. Schulte
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Non-covalent functionalisation of carbon nanotubes for the development of epoxy/ MWCNT nanocomposites. Conference ChemOnTubes. Arcachon, France (2010)
L.A.S.A. Prado, S.T. Buschhorn, S. Shakeri, C. Zhou, I.J. Zvonkina, A.K. Schlarb, K. Schulte
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Performance of CNT-reinforced Epoxy Resins in Tribological Applications (composite). Conference of the International Union of Materials Research Societies. Qingdao, China (2010)
A.K. Schlarb, I.J. Zvonkina, L.A.S.A. Prado, K. Schulte
