Ultra-high Molecular Weight Polyethylene /Graphite Nanocomposites Prepared by High-energy Cryomilling
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Ultra-high Molecular Weight Polyethylene /Graphite Nanocomposites Prepared by Highenergy Cryomilling. Sofía Vazquez-Rodriguez1, 2, Gloria E. Rodríguez-Vázquez1, 2, Selene Sepulveda-Guzman1,2, Martín E. Reyes-Melo1, 2, Aaron Morelos-Gomez3, Rodolfo Cruz-Silva4, Mauricio Terrones4, 5, 6 1
Universidad Autónoma de Nuevo León, FIME, San Nicolas de los Garza, N. L., Mexico. Universidad Autónoma de Nuevo Leon, CIIDIT, Apodaca, N. L., Mexico. 3 Faculty of Engineering, Shinshu University, Wakasato, Japan. 4 Research Center for Exotic Nanocarbons (JST), Shinshu University, Wakasato, Japan. 5 Department of Physics, The Pennsylvania State University, University Park, PA, United States. 6 Department of Materials Science and Engineering & Materials Research Institute, The Pennsylvania State University, University Park, PA, United States. 2
ABSTRACT Ultra-high molecular weight polyethylene/graphite nanocomposites were prepared by high-energy cryogenic milling followed by syntering. Microstructure changes shows that graphite was reduced to graphite nanoplatelets by high-energy cryomilling and partial exfoliation of graphite to few layered graphene nanoplatelets occurred in a small extent. The resulting nanocomposites revealed high electrical conductivity and good mechanical performance. Thermal characterization of the nanocomposites was also carried out by differential scanning calorimetry. INTRODUCTION Ultrahigh molecular weight polyethylene (UHMWPE) is a very interesting polymer due to its outstanding mechanical properties, nevertheless its processing is difficult due to the lack of flow in the molten state. For this reason, the fabrication of composites using UHMWPE is a real challenge. However, high-energy cryomilling could be a a new alternative process to incorporate carbon-based materials into polymer.1-3 Cryomilling process consists in milling polymer sample at temperature of liquid nitrogen, using a steel impactor bar which is moved at certainly frequency during a period of time in a vial container. Graphite is becoming an excellent nanofiller because of can be delaminated into individual graphene sheets promoting good mechanical and electrical properties.4 However the graphite-polymer nanocomposite preparation by conventional processing can promote a bad dispersion and exfoliation of graphite.5 For this reason, new potential processing methods, such as solid-state shear pulverization (SSSP) and cryogenic milling has been studied to improve graphite dispersion into polymer.1-3 In polypropylene-graphite nanocomposites obtained by SSSP with 2.5 wt% of exfoliated graphite increased Young’s module around 100% compared to neat PP1,3. Preparation of PP/graphite composite as polymer matrix using cryomilling showed that a partial exfoliation into nanoplatelets are obtained at 200 min of cryomilling and besides a melt mixing process, it is possible enhance the dispersion of graphite into polymer.
In this work, UHMWPE/graphite nanocomposites were prepared by cryomilling, to prepared films by compression molding. The partial exfo
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