The identification of various assorted occupational and consumer hazards in nanotechnology necess... more The identification of various assorted occupational and consumer hazards in nanotechnology necessitates the development of efficient risk management systems, in order to adequately safeguard vulnerable parties, while not hindering research progress. Driven by the need for advanced risk assessment methods, we initiated development of a digital tool intended to support such operations. Our tool is being designed as an assistive platform for smalland medium-scale facilities/laboratories producing and using nanomaterials. Studying the progress made in analogous systems in recent years [1] [2], it was determined that our approach should be steered towards more specialized risk assessment techniques. Specifically, the risk assessment process is organized in three connected but discretely studied parts (Hazard, Probability and Exposure Assessments). This platform combines existing scientific advances in nano-risk assessment with established methods in the field of workplace safety and heal...
Research into recycling carbon fibres for sustainable manufacturing has led to lighter high stren... more Research into recycling carbon fibres for sustainable manufacturing has led to lighter high strength recycled components for the aerospace industry and novel heated materials for garments and food bags. Carbon fibre is energy intensive to manufacture and most waste goes to landfill. Recycling has been pioneered at Nottingham to produce short individual filaments in a fluffy formwhich are both cost-saving in manufacturing and environmentally friendly. The team isre also developing materials with appropriate quality control methods so that designers and manufacturers will have confidence in using recycled materials in future. Early work used injection molding to produce fibre reinforced thermoplastic composite materials for the aerospace industry. This success has led to the Boeing Corporation funding further carbon fibre recycling research and product development in 2011 with a new three year £1.89 milliion programme. After recovering from the largest decline in the history of the ca...
The purpose of this work is to investigate the effects on the properties of poly-dimethylsiloxane... more The purpose of this work is to investigate the effects on the properties of poly-dimethylsiloxane-based coatings with the incorporation of multi-walled carbon nanotubes (MWCNT). For this reason, two types of MWCNT were examined (pristine and functionalised with carboxyl groups). An optimised dispersion method was employed to synthesise coatings with different wt-% concentrations of CNT, using different solvents. The morphology of the nanocomposite coatings was studied under optical and scanning electron microscopy. Moreover, their hydrophobic/hydrophilic behaviour was investigated by contact angle measurements. Furthermore, nanoindentation and nanoscratch tests were conducted to evaluate the nanomechanical properties. The results revealed an optimal threshold concentration of 0.1 wt-% in CNT that combines both acceptable dispersibility and mechanical enhancement of the composite coating. It was proven that the increase in CNT content deteriorates the surface and mechanical properties of the coatings.
Dissimilar friction stir welding between aluminum alloys thick plates reinforced with TiC nanopar... more Dissimilar friction stir welding between aluminum alloys thick plates reinforced with TiC nanoparticles was conducted. The defect-free welds are characterized by good mechanical mixing between the joined materials as well as by good nanoparticle distribution and further grain refinement in comparison with the unreinforced weld. The local mechanical behavior of the produced metal matrix composites was studied and compared with their bulk counterparts and parent materials. Specifically, the measured mechanical properties in microscale and nanoscale (namely hardness and elastic modulus) are correlated with microstructure and the presence of fillers. The hardness, elastic modulus, ultimate tensile strength, percentage of elongation, and yield values increase with the presence of TiC nanoparticles.
ABSTRACT In this work, a radio frequency discharged plasma generated in air atmosphere by pressur... more ABSTRACT In this work, a radio frequency discharged plasma generated in air atmosphere by pressure has been used to modify polylactic acid (PLA) surface. The results were evaluated through nanoindentation testing. Contact angle measurements revealed a gradual transition to a more hydrophilic state with increasing polarity after plasma treatment, while partial recovery to their untreated state during 10 day storage in air was evidenced. The results were evaluated through nanoindentation testing. All PLA samples exhibited an almost hard-like surface area where hardness and elastic modulus are enhanced. The activity of the plasma creates a higher cross-linking density within the material in the surface region. For higher displacements, both H and E tend to reach pristine PLA's values. Hardness values reveal surface hardening due to plasma treatment except for 180 s etching time, where hardness is slightly decreased possibly due to surface deformation. The change of H/E slope reveals the strengthening of oxygen plasma etched PLA with 180 s of etching time with increasing displacement. Keywords: Plasma treating, Polylactic acid, Nanomechanical properties References 1. Suhr H.: ‘Applications of nonequilibrium plasmas to organic chemistry’, in ‘Techniques and applications of plasma chemistry’, (ed. Hollahan J. and Bell A. T.., 2nd edn, 57; 1974, New York, J. Wiley and Sons. 2. Yasuda H.: ‘Plasma for modification of polymers’, J. Macromol. Sci. Chem. A, 1976, 10A, 383–420. 3. Liston E. M., Martinu L. and Wertheimer M. R.: ‘Plasma surface modification of polymers for improved adhesion: a critical review’, J. Adhes. Sci. Technol., 1993, 7, (10), 1091–1127. 4. Chan C. M.: ‘Polymer surface modification and characterization’, 225–263; 1994, Munich, Hanser Publishers. 5. Piskin E.: ‘Plasma processing of biomaterials’, J. Biomater. Sci. Polym. Ed., 1992, 4, 45–60. 6. Gombotz W. R. and Hoffman A. S.: ‘Gas-discharge techniques for biomaterial modification’, CRC Crit. Rev. Biocompat., 1987, 4, 1–42. 7. Ratner B. D., Chilkoti A. and Lopez G. P.: ‘Plasma deposition and treatment for biomaterial applications’, in ‘Plasma deposition, treatment and etching of polymers’, (ed. d'Agostino R.., 463–516; 1990, San Diego, CA, Academic Press. 8. Favia P. and d'Agostino R.: ‘Plasma treatments and plasma deposition of polymers for biomedical applications’, Surf. Coat. Technol., 1998, 98, 1102. 9. Loh I.-H.: ‘Plasma surface modification in biomedical applications’, Med. Device Technol., 1999, 10, 24–30. 10. Terlingen J. G. A.: ‘Introduction of functional groups at polymer surfaces by glow discharge techniques’, ‘PhD thesis’; 1993, Enschede, The Netherlands, University of Twente. 11. Groenewoud L. M. H.: ‘Transparent and conductive polymer layers by gas plasma techniques’, 2000, Enschede, The Netherlands, University of Twente. 12. Takens G. A.: ‘Functionalization of polymeric surfaces by oxidative gas plasma treatment’, 1997, Enschede, The Netherlands, University of Twente. 13. Lens J. P.: ‘Gas plasma immobilization of surfactants to improve the blood compatibility of polymeric surfaces’, 1996, Enschede, The Netherlands, University of Twente. 14. Klomp A. J. A.: ‘Design of surface modified poly(ethylene terephthalate) non-wovens for the removal of leukocytes from platelet concentrates’, 1998, Enschede, The Netherlands, University of Twente. 15. Chou S. Y., Krauss P. R. and Renstrom P. J.: ‘Imprint lithography with 25-nanometer resolution’, Science, 1996, 272, 85–87. 16. Mansky P., Harrison C. K., Chaikin P. M., Register R. A. and Yao N.: ‘Nanolithographic templates from diblock copolymer thin films’, Appl. Phys. Lett., 1996, 68, (18), 2586–2588. 17. Mansky P., DeRouchey J., Russell T. P., Mays J., Pitsikalis M., Morkved T. and Jaeger H.: ‘Large-area domain alignment in block copolymer thin films using electric fields’, Macromolecules, 1998, 31, 4399–4401. 18. Morkved T. L., Lu M., Urbas A. M., Ehrichs E. E., Jaeger H. M., Mansky P. and Russell T. P.: ‘Local control of microdomain orientation in diblock copolymer thin films with electric fields’, Science, 1996, 273, (5277), 931–933. 19. Park M., Harrison C., Chaikin P. M., Register R. A. and Adamson D. H.: ‘Block copolymer lithography: periodic arrays of ∼1011 holes in 1 square centimeter’, Science, 1997, 276, (5317), 1401–1404. 20. Mansky P., Chaikin P. and Thomas E. L.: ‘Monolayer films of diblock copolymer microdomains for nanolithographic applications’, J. Mater. Sci., 1995, 30, 1987–1992. 21. Harrison C., Park M., Chaikin P. M., Register R. A. and Adamson D. H.: ‘Lithography with a mask of block copolymer microstructures’, J. Vac. Sci. Technol. B, 1998, 16B, 544–552. 22. Spatz J. P., Eibeck P., Mossmer S., Moller M., Herzog T. and Ziemann P.: ‘Ultrathin diblock copolymer/titanium laminates – a tool for nanolithography’, Adv. Mater., 1998, 10, (11), 849–852. 23. Lammertink R. G. H., Hempenius M. A., van den Enk J. E., Chan V. Z. H., Thomas E. L. and Vancso G. J.:…
ABSTRACT Dissimilar friction stir welds were produced in 3 mm thick plates of AA6082-T6 and AA508... more ABSTRACT Dissimilar friction stir welds were produced in 3 mm thick plates of AA6082-T6 and AA5083-H111 aluminum alloys using SiC as reinforcing material. The optimum weld presents a good distribution of nanoparticles in the weld nugget and mechanical mixing of the two alloys as well as further grain refinement compared to the one without nanoparticles. Higher hardness in the weld nugget is also evidenced, followed by enhanced ultimate tensile strength and elongation values. All specimens, after the tensile test, were lead to fracture at the heat affected zone of AA6082-T6 and specifically at the region of the lowest hardness.
The development of new technology that prevents corrosion of aluminium alloys (AA) 2024-T3 was ma... more The development of new technology that prevents corrosion of aluminium alloys (AA) 2024-T3 was made. AA 2024-T3 panels were coated with two layers the first one consists of conductive polymers (CP) and the second one, on the top, is made of sol–gel coatings. ...
ABSTRACT Cyclo olefin polymer (COP) surfaces, treated in oxygen plasmas under highly anisotropic ... more ABSTRACT Cyclo olefin polymer (COP) surfaces, treated in oxygen plasmas under highly anisotropic conditions to favor roughness formation, are coated with thin hydrophobic films to form surfaces of enhanced hydrophobicity. As hydrophobic coatings, plasma-deposited fluorocarbon or spin-coated Teflon thin films are implemented. Nanoindentation and nanoscratch experiments have been employed to elucidate the effect of plasma treatment on the mechanical and tribological performance of the synthesized materials. It is shown that short-time plasma treatment slightly changes mechanical and tribological properties of plasma-nanotextured COP, as compared to untreated. The plasma deposited hydrophobic film on the COP surfaces presents good adhesion and it effectively protects the surfaces, reducing plastic deformation.
The identification of various assorted occupational and consumer hazards in nanotechnology necess... more The identification of various assorted occupational and consumer hazards in nanotechnology necessitates the development of efficient risk management systems, in order to adequately safeguard vulnerable parties, while not hindering research progress. Driven by the need for advanced risk assessment methods, we initiated development of a digital tool intended to support such operations. Our tool is being designed as an assistive platform for smalland medium-scale facilities/laboratories producing and using nanomaterials. Studying the progress made in analogous systems in recent years [1] [2], it was determined that our approach should be steered towards more specialized risk assessment techniques. Specifically, the risk assessment process is organized in three connected but discretely studied parts (Hazard, Probability and Exposure Assessments). This platform combines existing scientific advances in nano-risk assessment with established methods in the field of workplace safety and heal...
Research into recycling carbon fibres for sustainable manufacturing has led to lighter high stren... more Research into recycling carbon fibres for sustainable manufacturing has led to lighter high strength recycled components for the aerospace industry and novel heated materials for garments and food bags. Carbon fibre is energy intensive to manufacture and most waste goes to landfill. Recycling has been pioneered at Nottingham to produce short individual filaments in a fluffy formwhich are both cost-saving in manufacturing and environmentally friendly. The team isre also developing materials with appropriate quality control methods so that designers and manufacturers will have confidence in using recycled materials in future. Early work used injection molding to produce fibre reinforced thermoplastic composite materials for the aerospace industry. This success has led to the Boeing Corporation funding further carbon fibre recycling research and product development in 2011 with a new three year £1.89 milliion programme. After recovering from the largest decline in the history of the ca...
The purpose of this work is to investigate the effects on the properties of poly-dimethylsiloxane... more The purpose of this work is to investigate the effects on the properties of poly-dimethylsiloxane-based coatings with the incorporation of multi-walled carbon nanotubes (MWCNT). For this reason, two types of MWCNT were examined (pristine and functionalised with carboxyl groups). An optimised dispersion method was employed to synthesise coatings with different wt-% concentrations of CNT, using different solvents. The morphology of the nanocomposite coatings was studied under optical and scanning electron microscopy. Moreover, their hydrophobic/hydrophilic behaviour was investigated by contact angle measurements. Furthermore, nanoindentation and nanoscratch tests were conducted to evaluate the nanomechanical properties. The results revealed an optimal threshold concentration of 0.1 wt-% in CNT that combines both acceptable dispersibility and mechanical enhancement of the composite coating. It was proven that the increase in CNT content deteriorates the surface and mechanical properties of the coatings.
Dissimilar friction stir welding between aluminum alloys thick plates reinforced with TiC nanopar... more Dissimilar friction stir welding between aluminum alloys thick plates reinforced with TiC nanoparticles was conducted. The defect-free welds are characterized by good mechanical mixing between the joined materials as well as by good nanoparticle distribution and further grain refinement in comparison with the unreinforced weld. The local mechanical behavior of the produced metal matrix composites was studied and compared with their bulk counterparts and parent materials. Specifically, the measured mechanical properties in microscale and nanoscale (namely hardness and elastic modulus) are correlated with microstructure and the presence of fillers. The hardness, elastic modulus, ultimate tensile strength, percentage of elongation, and yield values increase with the presence of TiC nanoparticles.
ABSTRACT In this work, a radio frequency discharged plasma generated in air atmosphere by pressur... more ABSTRACT In this work, a radio frequency discharged plasma generated in air atmosphere by pressure has been used to modify polylactic acid (PLA) surface. The results were evaluated through nanoindentation testing. Contact angle measurements revealed a gradual transition to a more hydrophilic state with increasing polarity after plasma treatment, while partial recovery to their untreated state during 10 day storage in air was evidenced. The results were evaluated through nanoindentation testing. All PLA samples exhibited an almost hard-like surface area where hardness and elastic modulus are enhanced. The activity of the plasma creates a higher cross-linking density within the material in the surface region. For higher displacements, both H and E tend to reach pristine PLA's values. Hardness values reveal surface hardening due to plasma treatment except for 180 s etching time, where hardness is slightly decreased possibly due to surface deformation. The change of H/E slope reveals the strengthening of oxygen plasma etched PLA with 180 s of etching time with increasing displacement. Keywords: Plasma treating, Polylactic acid, Nanomechanical properties References 1. Suhr H.: ‘Applications of nonequilibrium plasmas to organic chemistry’, in ‘Techniques and applications of plasma chemistry’, (ed. Hollahan J. and Bell A. T.., 2nd edn, 57; 1974, New York, J. Wiley and Sons. 2. Yasuda H.: ‘Plasma for modification of polymers’, J. Macromol. Sci. Chem. A, 1976, 10A, 383–420. 3. Liston E. M., Martinu L. and Wertheimer M. R.: ‘Plasma surface modification of polymers for improved adhesion: a critical review’, J. Adhes. Sci. Technol., 1993, 7, (10), 1091–1127. 4. Chan C. M.: ‘Polymer surface modification and characterization’, 225–263; 1994, Munich, Hanser Publishers. 5. Piskin E.: ‘Plasma processing of biomaterials’, J. Biomater. Sci. Polym. Ed., 1992, 4, 45–60. 6. Gombotz W. R. and Hoffman A. S.: ‘Gas-discharge techniques for biomaterial modification’, CRC Crit. Rev. Biocompat., 1987, 4, 1–42. 7. Ratner B. D., Chilkoti A. and Lopez G. P.: ‘Plasma deposition and treatment for biomaterial applications’, in ‘Plasma deposition, treatment and etching of polymers’, (ed. d'Agostino R.., 463–516; 1990, San Diego, CA, Academic Press. 8. Favia P. and d'Agostino R.: ‘Plasma treatments and plasma deposition of polymers for biomedical applications’, Surf. Coat. Technol., 1998, 98, 1102. 9. Loh I.-H.: ‘Plasma surface modification in biomedical applications’, Med. Device Technol., 1999, 10, 24–30. 10. Terlingen J. G. A.: ‘Introduction of functional groups at polymer surfaces by glow discharge techniques’, ‘PhD thesis’; 1993, Enschede, The Netherlands, University of Twente. 11. Groenewoud L. M. H.: ‘Transparent and conductive polymer layers by gas plasma techniques’, 2000, Enschede, The Netherlands, University of Twente. 12. Takens G. A.: ‘Functionalization of polymeric surfaces by oxidative gas plasma treatment’, 1997, Enschede, The Netherlands, University of Twente. 13. Lens J. P.: ‘Gas plasma immobilization of surfactants to improve the blood compatibility of polymeric surfaces’, 1996, Enschede, The Netherlands, University of Twente. 14. Klomp A. J. A.: ‘Design of surface modified poly(ethylene terephthalate) non-wovens for the removal of leukocytes from platelet concentrates’, 1998, Enschede, The Netherlands, University of Twente. 15. Chou S. Y., Krauss P. R. and Renstrom P. J.: ‘Imprint lithography with 25-nanometer resolution’, Science, 1996, 272, 85–87. 16. Mansky P., Harrison C. K., Chaikin P. M., Register R. A. and Yao N.: ‘Nanolithographic templates from diblock copolymer thin films’, Appl. Phys. Lett., 1996, 68, (18), 2586–2588. 17. Mansky P., DeRouchey J., Russell T. P., Mays J., Pitsikalis M., Morkved T. and Jaeger H.: ‘Large-area domain alignment in block copolymer thin films using electric fields’, Macromolecules, 1998, 31, 4399–4401. 18. Morkved T. L., Lu M., Urbas A. M., Ehrichs E. E., Jaeger H. M., Mansky P. and Russell T. P.: ‘Local control of microdomain orientation in diblock copolymer thin films with electric fields’, Science, 1996, 273, (5277), 931–933. 19. Park M., Harrison C., Chaikin P. M., Register R. A. and Adamson D. H.: ‘Block copolymer lithography: periodic arrays of ∼1011 holes in 1 square centimeter’, Science, 1997, 276, (5317), 1401–1404. 20. Mansky P., Chaikin P. and Thomas E. L.: ‘Monolayer films of diblock copolymer microdomains for nanolithographic applications’, J. Mater. Sci., 1995, 30, 1987–1992. 21. Harrison C., Park M., Chaikin P. M., Register R. A. and Adamson D. H.: ‘Lithography with a mask of block copolymer microstructures’, J. Vac. Sci. Technol. B, 1998, 16B, 544–552. 22. Spatz J. P., Eibeck P., Mossmer S., Moller M., Herzog T. and Ziemann P.: ‘Ultrathin diblock copolymer/titanium laminates – a tool for nanolithography’, Adv. Mater., 1998, 10, (11), 849–852. 23. Lammertink R. G. H., Hempenius M. A., van den Enk J. E., Chan V. Z. H., Thomas E. L. and Vancso G. J.:…
ABSTRACT Dissimilar friction stir welds were produced in 3 mm thick plates of AA6082-T6 and AA508... more ABSTRACT Dissimilar friction stir welds were produced in 3 mm thick plates of AA6082-T6 and AA5083-H111 aluminum alloys using SiC as reinforcing material. The optimum weld presents a good distribution of nanoparticles in the weld nugget and mechanical mixing of the two alloys as well as further grain refinement compared to the one without nanoparticles. Higher hardness in the weld nugget is also evidenced, followed by enhanced ultimate tensile strength and elongation values. All specimens, after the tensile test, were lead to fracture at the heat affected zone of AA6082-T6 and specifically at the region of the lowest hardness.
The development of new technology that prevents corrosion of aluminium alloys (AA) 2024-T3 was ma... more The development of new technology that prevents corrosion of aluminium alloys (AA) 2024-T3 was made. AA 2024-T3 panels were coated with two layers the first one consists of conductive polymers (CP) and the second one, on the top, is made of sol–gel coatings. ...
ABSTRACT Cyclo olefin polymer (COP) surfaces, treated in oxygen plasmas under highly anisotropic ... more ABSTRACT Cyclo olefin polymer (COP) surfaces, treated in oxygen plasmas under highly anisotropic conditions to favor roughness formation, are coated with thin hydrophobic films to form surfaces of enhanced hydrophobicity. As hydrophobic coatings, plasma-deposited fluorocarbon or spin-coated Teflon thin films are implemented. Nanoindentation and nanoscratch experiments have been employed to elucidate the effect of plasma treatment on the mechanical and tribological performance of the synthesized materials. It is shown that short-time plasma treatment slightly changes mechanical and tribological properties of plasma-nanotextured COP, as compared to untreated. The plasma deposited hydrophobic film on the COP surfaces presents good adhesion and it effectively protects the surfaces, reducing plastic deformation.
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Papers by Elias Koumoulos