Effective volume-fraction optimization for thermal stress reduction in FGMs using irregularh-refinement

2003 ◽  
Vol 58 (5) ◽  
pp. 749-770 ◽  
Author(s):  
J. R. Cho ◽  
H. J. Park
Keyword(s):  
Thermal Stress ◽  
Stress Reduction ◽  
Volume Fraction ◽  
Effective Volume ◽  
Effective Volume Fraction

scholarly journals Calculation of the Electrical Conductivity of Polymer Nanocomposites Assuming the Interphase Layer Surrounding Carbon Nanotubes

Polymers ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 404 ◽  
Author(s):  
Yasser Zare ◽  
Kyong Yop Rhee
Keyword(s):  
Electrical Conductivity ◽  
Polymer Nanocomposites ◽  
Volume Fraction ◽  
Tunneling Effect ◽  
Interphase Layer ◽  
Conductive Network ◽  
Effective Volume ◽  
Effective Volume Fraction ◽  
Filler Fraction ◽  
High Fraction

The interphase layer surrounding nanoparticles can reflect the tunneling effect as the main mechanism of charge transferring in polymer/carbon nanotube (CNT) nanocomposites (PCNT). In this paper, the percolation threshold, effective volume fraction of CNT, and the portion of percolated filler after percolation are expressed by interphase and CNT waviness. Moreover, the developed terms are used to suggest the influences of CNT dimensions, interphase thickness, and waviness on the electrical conductivity of PCNT by conventional and developed models. Thin and long CNT, thick interphase, and low waviness obtain a high fraction of percolated CNT. However, the highest level of effective filler fraction is only calculated by the thinnest CNT and the thickest interphase. Furthermore, both models show that the thinnest and the longest CNT as well as the thickest interphase and the least CNT waviness cause the highest conductivity in PCNT, because they positively contribute to the formation and properties of the conductive network.

Reduction in Viscosity of an SBR Compound Caused by Mastication and Disagglomeration during Mixing

1994 ◽  
Vol 67 (4) ◽  
pp. 700-715 ◽  
Author(s):  
J. Clarke ◽  
P. K. Freakley
Keyword(s):  
Carbon Black ◽  
Strain Rate ◽  
Rheological Behavior ◽  
Dibutyl Phthalate ◽  
Volume Fraction ◽  
Relative Viscosity ◽  
Mixing Times ◽  
Effective Volume ◽  
Effective Volume Fraction

Abstract It would be advantageous to determine the causes of changes in rheological behavior of a compound during mixing, so that mixing times and conditions could be optimized to give the desired processing behavior and properties of the final product. The causes of changes in viscosity during mixing of a compound containing only elastomer and carbon black were investigated by examining concurrent changes in viscosity of the gum, density of the compound and degree of carbon-black disagglomeration. The reduction in viscosity occurring during mixing could be attributed to mastication of the elastomer and disagglomeration of the carbon black. The effect of mastication could be removed by calculating values of relative viscosity, using the viscosity of the gum treated in a similar way to the compound and with an allowance being made for strain-rate amplification. The decrease in relative viscosity of the compound with increased mixing was attributed to a reduction in effective volume fraction of filler caused by immobilized rubber being released as carbon black agglomerates were broken down. The dibutyl phthalate absorption (DBPA) value of the carbon black gave a good indication of the amount of immobilized rubber present in an agglomerate.

scholarly journals Towards Sophisticated 3D Interphase Modelling of Advanced Bionanocomposites via Atomic Force Microscopy

2020 ◽  
Vol 2020 ◽  
pp. 1-22
Author(s):  
Mohanad Mousa ◽  
Yu Dong
Keyword(s):  
Experimental Data ◽  
Volume Fraction ◽  
Hard Core ◽  
Theoretical Models ◽  
Halloysite Nanotubes ◽  
Accurate Estimation ◽  
Effective Volume ◽  
Force Microscopy ◽  
Effective Volume Fraction ◽  
Cloisite 30B

Nanomechanical properties and interphase dimensions of PVA bionanocomposites reinforced with halloysite nanotubes (HNTs) and Cloisite 30B montmorillonite (MMT) were evaluated by means of peak force quantitative nanomechanical mapping (PFQNM). A three-phase theoretical composite model was established based on hard-core–soft-shell structures consisting of hard mono-/polydispersed anisotropic particles and soft interphase and matrices. Halpin-Tsai model and Mori-Tanaka model were employed to predict experimentally determined tensile moduli of PVA bionanocomposites where effective volume fraction of randomly oriented nanoparticles resulted from the inclusion of interphase properties and volume fractions. Overall, it was suggested that the estimation of elastic modulus according to effective volume fraction of nanoparticles revealed better agreement with experimental data as opposed to that based upon their nominal volume fraction. In particular, the use of polydispersed HNTs and Cloisite 30B MMT clays with Fuller particulate gradation was proven to yield the best prediction when compared with experimental data among all proposed theoretical models. This study overcomes the neglected real interphase characteristics in modelling nanocomposite materials with much more accurate estimation of their mechanical properties.

Rheological Characteristics of Nanoparticle Compound Microencapsulated Phase Change Material Suspension

2009 ◽  
Author(s):  
Liang Wang ◽  
Guiping Lin ◽  
Yulong Ding
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Phase Change Material ◽  
Volume Fraction ◽  
Rheological Characteristics ◽  
Effective Volume ◽  
Effective Volume Fraction ◽  
Microencapsulated Phase Change Material ◽  
Change Material ◽  
Fraction Method

Microencapsulated phase change material (MPCM) suspensions have large specific heat due to the latent heat of the phase change material and enhance the convective heat transfer consequently. However low thermal conductivity of the phase change material diminishes the heat transfer performance of the MPCM suspensions. To improve the thermal conductivity of the MPCM suspensions, TiO2 nanoparticles were added into the MPCM suspensions to formulate a novel thermal fluid—nanoparticle compound microencapsulated phase change material suspensions. In this paper, the rheological characteristics and shear viscosities of such slurries using a Bolin CVO rheometer (Malvern Instruments) over a range of shear rate (5–500s−1), MPCM concentration (0–20wt%) and TiO2 nanoparticle concentration 0.5wt% at temperature (20°C–40°C). The result shows that the viscosities of NCMPCM suspensions are almost independent of the shear rate, indicating Newtonian fluid under the conditions of this work and the viscosities depend strongly on temperature which fits well with the VTF function. Based on the effective volume fraction method and Vand equation, two methods that predict the viscosity of nanoparticle compound microencapsulated phase change material suspensions was analyzed and the result shows that the prediction data the effective volume fraction method fit the measurements well.

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