The mechanical properties of vulcanizates based on Hydrogenated Nitrile Butadiene Rubber (HNBR) are extremely attractive for many applications in comparison with other elastomers. In fact such type of materials exhibits good stability towards thermal ageing and better properties at low temperatures compared with other heat and oil resistant elastomers. This combination of properties is opening up a broad range of applications, mainly in the automotive industry like belts, seals and hoses. With reference to the in-service life of such components, it clearly appears that the obtainement of good fracture properties of HNBR-based systems is of basic importance. The present work is aimed at investigating the fracture behaviour of vulcanized HNBR systems containing different nanofillers, such as silica and multi wall carbon nanotubes (1). The fracture behavior of the different nanocomposites is studied by a fracture mechanics approach based on J-integral methodology to evaluate the material resistance to crack initiation (JIC) and propagation (J-resistance curve) (2). The fracture tests are carried out using SEN(T) specimens. During each test the deformation and fracture processes are recorded by a camera at different short time intervals, allowing the evaluation of the crack tip opening displacement at different extents of crack propagation. The evaluation of the corresponding J-values, determined by proper integration of load-displacement curve, allows the construction of J(CTOD) resistance curve (2). For the systems investigated the results obtained, with varying the type and content of nanofiller, are analysed and discussed. The results point out that multiwall carbon nanotubes are markedly more efficient than silica in promoting fracture resistance with particular reference to fracture initiation. Further, the comparison of the results with those obtained for other filled elastomeric systems confirms the very high toughening efficiency of carbon nanotubes. References 1. D. Felhös, J. Karger-Kocsis, D. Xu (2008). "Tribological Testing of Peroxide Cured HNBR with Different MWCNT and Silica Contents under Dry Sliding and Rolling Conditions Against Steel”. Journal of Applied Polymer Science, DOI 10.1002/app.27624 2. G. Ramorino, C. Andreana, O. De Feo, T. Riccò (2006). “Fracture Resistance of Natural Rubber/Layered Silicate Nanocomposites. Application of J-Testing Method”. 13th Conference on Deformation, Yielding and Fracture of Polymers. April, 10-13 Th, Rolduc Abbey, Kerkrade (NE).
A fracture mechanics investigation of vulcanized HNBR filled with different nanofillers
RAMORINO, Giorgio;AGNELLI, Silvia;RICCO', Theonis
2009-01-01
Abstract
The mechanical properties of vulcanizates based on Hydrogenated Nitrile Butadiene Rubber (HNBR) are extremely attractive for many applications in comparison with other elastomers. In fact such type of materials exhibits good stability towards thermal ageing and better properties at low temperatures compared with other heat and oil resistant elastomers. This combination of properties is opening up a broad range of applications, mainly in the automotive industry like belts, seals and hoses. With reference to the in-service life of such components, it clearly appears that the obtainement of good fracture properties of HNBR-based systems is of basic importance. The present work is aimed at investigating the fracture behaviour of vulcanized HNBR systems containing different nanofillers, such as silica and multi wall carbon nanotubes (1). The fracture behavior of the different nanocomposites is studied by a fracture mechanics approach based on J-integral methodology to evaluate the material resistance to crack initiation (JIC) and propagation (J-resistance curve) (2). The fracture tests are carried out using SEN(T) specimens. During each test the deformation and fracture processes are recorded by a camera at different short time intervals, allowing the evaluation of the crack tip opening displacement at different extents of crack propagation. The evaluation of the corresponding J-values, determined by proper integration of load-displacement curve, allows the construction of J(CTOD) resistance curve (2). For the systems investigated the results obtained, with varying the type and content of nanofiller, are analysed and discussed. The results point out that multiwall carbon nanotubes are markedly more efficient than silica in promoting fracture resistance with particular reference to fracture initiation. Further, the comparison of the results with those obtained for other filled elastomeric systems confirms the very high toughening efficiency of carbon nanotubes. References 1. D. Felhös, J. Karger-Kocsis, D. Xu (2008). "Tribological Testing of Peroxide Cured HNBR with Different MWCNT and Silica Contents under Dry Sliding and Rolling Conditions Against Steel”. Journal of Applied Polymer Science, DOI 10.1002/app.27624 2. G. Ramorino, C. Andreana, O. De Feo, T. Riccò (2006). “Fracture Resistance of Natural Rubber/Layered Silicate Nanocomposites. Application of J-Testing Method”. 13th Conference on Deformation, Yielding and Fracture of Polymers. April, 10-13 Th, Rolduc Abbey, Kerkrade (NE).I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
