Mechanical properties of light-cured composites reinforced with micro- and nanoparticles
Mariusz Andrzejczuk, Małgorzata Lewandowska, Krzysztof J. Kurzydłowski Politechnika Warszawska, Wydział Inżynierii Materiałowej, ul. Wołoska 141, 02-507 Warszawa
Quarterly No. 1, 2005 pages 75-79
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abstract The aim of this work was to study the influence of ceramic micro and nanoparticles on the mechanical properties of the composites. A series of ceramic-polymer composites used for permanent fillings was fabricated. Ceramic glass of an average particle size of a few μm and nanosilica of the average particle size of 40 nm were used as the fillers. The influence of the amount of inorganic filler on the mechanical properties such as the flexural strength, Young modulus and microhardness HV0.2 was determined (Fig. 1). It was found that an increase of the volume fraction of the filler leads to a significant improvement of the mechanical properties of the composites. Figure 2 shows the influence of the nanofiller (nanosilica) and its surface treatment on the mechanical properties of the composites that contain both micro and nanofillers. The addition of nanosilica improves the mechanical properties of the composite, but only when the nanoparticles are surface treated. Otherwise, the mechanical properties are drasticaly worsened. The optimum concetration of nanoparticles was estimated at 10÷15%. At 20% of nanosilica, the mechanical properties of the composite are worse than those obtained at smaller amounts of n-SiO2. This may be due to the fact that at greater n-SiO2 amounts, the nanoparticles may aglomerate. This suggestion was confirmed by SEM observations of the fracture surface. Figure 3 shows examples of the fracture surfaces of the composite with 60% of glass particles (a, b) and the composite with 40% of glass particles plus 20% of nanosilica (c,d). Further research will be aimed at avoiding the aglomeration of nanoparticles. Key words: ceramic-polymer composites, dental fillings, mechanical properties