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Preparation and mechanical properties of graphite filled HDPE nanocomposites

Sarikanat M., Sever K., Erbay E., Güner F., Tavman I., Turgut A., Seki Y., Özdemir I.

Archives of Materials Science and Engineering

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2011

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Vol. 50, nr 2

120-124

EN

Purpose: The design and manufacture of lightweight polymer composites with high electrical and thermal conductivity have been a research focus in recent years. In this study, tensile strength and modulus of elasticity of nanocomposites formed by high density polyethylene (HDPE) matrix and graphite powder filler material were determined. Design/methodology/approach: In this study the conductive filler was graphite with an average particle size of 400 nm and purity of 99.9%, the matrix material was high density polyethylene (HDPE) with a density of 0.968 g/cm3 and a melt index of 5.8 g/10 min, supplied by Petkim A.Ş.- Izmir. Nanocomposites containing up to 30 weight percent of graphite powder filler material were prepared by mixing them in a Brabender Plasticorder at 180°C for 15 minutes. Tensile strength and modulus of elasticity of nanocomposites formed were determined as functions of graphite powder content. Findings: An increase in tensile strength and modulus of elasticity was observed with increasing graphite powder content from 0 to 6%. However, for further increasing the graphite content, tensile strength decreases while modulus of elasticity continued to increase in the composite. Practical implications: Since natural graphite (NG) has a high electrical conductivity at room temperature, it is considered an ideal candidate for manufacturing conductive polymer composites. The recent advancement of nano-scale compounding technique enables the preparation of highly electrically conductive polymeric nanocomposites with low loading of conductive fillers. Nanocomposites may offer enhanced physical features such as increased stiffness, strength, barrier properties and heat resistance, without loss of impact strength in a very broad range of common synthetic or natural polymers. Originality/value: To see the effect of conducting fillers on mechanical properties of HDPE based nanocomposites, graphite particle 400 nm in size were used.

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Measurement of heat capacity and thermal conductivity of HDPE/expanded graphite nanocomposites by differential scanning calorimetry

Tavman I., Aydogdu Y., Kök M., Turgut A., Ezan A.

Archives of Materials Science and Engineering

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2011

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Vol. 50, nr 1

56-60

EN

Purpose: In this study, heat capacity and thermal conductivity of nanocomposites formed by high density polyethylene (HDPE) matrix and expanded graphite (EG) conductive filling material were investigated. Design/methodology/approach: Nanocomposites containing up to 20 weight percent of expanded graphite filler material were prepared by mixing them in a Brabender Plasticorder. Two grades of expanded graphite fillers were used namely expanded graphite with 5 ěm (EG5) and 50 ěm (EG50) in diameter. Heat capacity and thermal conductivity of pure HDPE and the nanocomposites were measured using differential scanning calorimetry (DSC). Findings: A substantial increase in thermal conductivity was observed with the addition of expanded graphite to HDPE. Thermal conductivity increased from 0.442 W/m.K for pure HDPE to 0.938 W/m.K for nanocomposites containing 7% by weight of expended graphite. Heat capacity increases with the increase in temperature for both pure HDPE and the nanocomposites filled with expanded graphite and no appreciable difference in the values of heat capacity were detected due to particle size. Heat capacity decreased with increasing graphite particle content for both particle size, following the low of mixtures. Practical implications: Layers of expanded graphite have become of intense interest as fillers in polymeric nanocomposites. Upon mixing the expanded graphite intercalates and exfoliates into nanometer thickness sheets due to their sheet-like structure and week bonds normal to the graphite sheets. That way they have very big surface area and high aspect ratio (200.1500) what results in a formation of percolating network at very low filler content. The nanoparticles usage results in significant improvement in thermal, mechanical, and electrical properties of polymers even with very low loading levels compared with microparticles. Originality/value: To see the effect of conducting fillers on thermal conductivity and heat capacity two different sizes of expanded graphite were used.

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Preparation and characterization of highly electrically and thermally conductive polymeric nanocomposites

Tavman I., Çeçen V., Özdemir I., Turgut A., Krupa I., Omastova M., Novak I.

Archives of Materials Science and Engineering

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2009

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Vol. 40, nr 2

84-88

EN

Purpose: The conducting polymers and polymeric composites have attracted considerable attention in recent years because of their potential applications in advanced technologies, for example, in antistatic coatings, electromagnetic shielding. Design/methodology/approach: In this study the conductive fillers were expanded graphite (EG) and untreated graphite (UG), the base material was ethylene- vinyl acetate copolymer (EVA). Nanocomposites containing up to 30 volume % of filler material were prepared by mixing them in a Brabender Plasticorder. Findings: The increase in thermal conductivity was more pronounced for EVA-UG nanocomposites than EVA-EG nanocomposites. Practical implications: The recent advancement of nano-scale compounding technique enables the preparation of highly electrically conductive polymeric nanocomposites with very low loading of conductive fillers. Compared with traditional composites, nanocomposites may offer enhanced physical features such as increased stiffness, strength, barrier properties and heat resistance, without loss of impact strength in a very broad range of common synthetic or natural polymers. Originality/value: The introduction of electrically conductive fillers such as graphite, carbon black, metal and metal oxide powders into the polymeric matrix is a promising approach to fabricate electrically conductive polymeric materials.

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Experimental investigation of viscosity and thermal conductivity of suspensions containing nanosized ceramic particles

Tavman I., Turgut A., Chirtoc M., Schuchmann H.P., Tavman S.

Archives of Materials Science and Engineering

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2008

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Vol. 34, nr 2

99-103

EN

Purpose: In this study we report measurements of effective thermal conductivity by using 3ω method and effective viscosity by vibro-viscometer for SiO2-water and Al2O3-water nanofluids at different particle concentrations and temperatures. Design/methodology/approach : The effective thermal conductivity of nanofluids is measured by a technique based on a hot wire thermal probe with ac excitation and 3ω lock-in detection. There is presented an experimental study of thermal conductivity and viscosity of nanofluids. It was investigated Alumina and Silica nanoparticles in water with different particle concentrations. Findings: Measured results showed that the effective thermal conductivity of nanofluids increase as the concentration of the particles increase but not anomalously as indicated in the majority of the literature and this enhancement is very close to Hamilton-Crosser model, also this increase is independent of the temperature. The effective viscosities of these nanofluids increased by the increasing particle concentration and decrease by the increase in temperature, and can not be predicted by Einstein model. Practical implications: The results show that for our samples, thermal conductivity values are inside the limits of (moderately lower than) Hamilton-Crosser model. Originality/value: Experiments at different temperatures show that relative thermal conductivity of nanofluids is not related with the temperature of the fluid.

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Preparation and characterization of highly electrically and thermally conductive polymeric nanocomposites

Tavman I., Krupa I., Cecen V., Omastova M., Novak I., Ozdemir I., Turgut A.

Archives of Materials Science

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2008

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Vol. 29, nr 1-2

77-83

EN

The conducting polymers and polymeric composites have attracted considerable attention in recent years because of their potential applications in advanced technologies, for example, in antistatic coatings, electromagnetic shielding. The introduction of electrically conductive fillers such as graphite, carbon black, metal and metal oxide powders into the polymeric matrix is a promising approach to fabricate electrically conductive polymeric materials. The recent advancement of nano-scale compounding technique enables the preparation of highly electrically conductive polymeric nanocomposites with very low loading of conductive fillers. Compared with traditional composites, nanocomposites may offer enhanced physical features such as increased stiffness, strength, barrier properties and heat resistance, without loss of impact strength in a very broad range of common synthetic or natural polymers. In this study the conductive fillers were expanded graphite (EG) and untreated graphite (UG), the base material was ethylene- vinyl acetate copolymer (EVA). Nanocomposites containing up to 30 volume % of filler material were prepared by mixing them in a Brabender Plasticorder. The increase in thermal conductivity was more pronounced for EVA-UG nanocomposites than EVA-EG nanocomposites.