scholarly journals Understanding porosity and temperature induced variabilities in interface, mechanical characteristics and thermal conductivity of borophene membranes

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Van-Trung Pham ◽  
Te-Hua Fang
Keyword(s):  
Thermal Conductivity ◽  
Ambient Temperature ◽  
Young’S Modulus ◽  
Ultimate Strength ◽  
Mechanical Characteristics ◽  
Young's Modulus ◽  
Practical Application ◽  
Strength Failure ◽  
Zigzag Direction ◽  
Non Equilibrium Molecular Dynamics

AbstractEvaluating the effect of porosity and ambient temperature on mechanical characteristics and thermal conductivity is vital for practical application and fundamental material property. Here we report that ambient temperature and porosity greatly influence fracture behavior and material properties. With the existence of the pore, the most significant stresses will be concentrated around the pore position during the uniaxial and biaxial processes, making fracture easier to occur than when tensing the perfect sheet. Ultimate strength and Young’s modulus degrade as porosity increases. The ultimate strength and Young's modulus in the zigzag direction is lower than the armchair one, proving that the borophene membrane has anisotropy characteristics. The deformation behavior of borophene sheets when stretching biaxial is more complicated and rough than that of uniaxial tension. In addition, the results show that the ultimate strength, failure strain, and Young’s modulus degrade with growing temperature. Besides the tensile test, this paper also uses the non-equilibrium molecular dynamics (NEMD) approach to investigate the effects of length size, porosity, and temperature on the thermal conductivity (κ) of borophene membranes. The result points out that κ increases as the length increases. As the ambient temperature increases, κ decreases. Interestingly, the more porosity increases, the more κ decreases. Moreover, the results also show that the borophene membrane is anisotropic in heat transfer.

Effects of Stone-Wales Defects on the Thermal Conductivity of Carbon Nanotubes

2012 ◽  
Vol 134 (9) ◽  
Author(s):  
Li Wei ◽  
Feng Yanhui ◽  
Peng Jia ◽  
Zhang Xinxin
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Molecular Dynamics ◽  
Thermal Resistance ◽  
Ambient Temperature ◽  
Temperature Profile ◽  
Defect Position ◽  
Non Equilibrium Molecular Dynamics ◽  
Increasing Temperature ◽  
Dynamics Method

The thermal conductivity of carbon nanotubes with Stone-Wales (SW) defects was investigated using non-equilibrium molecular dynamics method. The defect effects were analyzed by the temperature profile and local thermal resistance of the nanotubes with one or more SW defects and further compared with perfect tubes. The influences of the defect concentration, the length, the chirality and the radius of tubes and the ambient temperature were studied. It was demonstrated that a sharp jump in the temperature profile occurred at defect position due to a higher local thermal resistance, thus dramatically reducing the thermal conductivity of the nanotube. As the number of SW defects increases, the thermal conductivity decreases. Relative to the chirality, the radius has greater effects on the thermal conductivity of tubes with SW defects. With the similar radius, the thermal conductivity of armchair nanotube is higher than that of zigzag one. The shorter nanotube is more sensitive to the defect than the longer one. Thermal conductivity of the nanotube increases with ambient temperature, reaches a peak, and then decreases with increasing temperature.

scholarly journals Neutron Multiple Number as a Factor Ruling Both the Abundance and Some Material Properties of Elements

2017 ◽  
Vol 6 (3) ◽  
pp. 37
Author(s):  
Yoshiharu Mae
Keyword(s):  
Thermal Conductivity ◽  
Young’S Modulus ◽  
Melting Temperature ◽  
Material Properties ◽  
Young's Modulus ◽  
Materials Properties ◽  
Unique Pattern ◽  
The Universe

The abundance of elements in the universe was plotted on the TC-YM diagram. The most abundant elements show the unique pattern drawing a quadrant. Next, the neutron multiple number, the number of neutron per proton in the nucleus, was introduced. The neutron multiple numbers of elements show the same pattern as the abundance of elements on the diagram. As a result, the abundance of elements shows a good correlation with neutron multiple numbers of elements. With increasing neutron multiple number, the abundance decreases. Besides, the neutron multiple number relates to the materials properties such as the Young’s modulus, thermal conductivity and melting temperature of elements.

scholarly journals Electronic, Mechanical and Elastic Anisotropy Properties of X-Diamondyne (X = Si, Ge)

Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3589 ◽  
Author(s):  
Qingyang Fan ◽  
Zhongxing Duan ◽  
Yanxing Song ◽  
Wei Zhang ◽  
Qidong Zhang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Shear Modulus ◽  
Young’S Modulus ◽  
Density Functional ◽  
Elastic Anisotropy ◽  
Young's Modulus ◽  
Wide Band ◽  
Band Gaps ◽  
Mechanical Anisotropy ◽  
Semiconductor Materials

The three-dimensional (3D) diamond-like semiconductor materials Si-diamondyne and Ge-diamondyne (also called SiC4 and GeC4) are studied utilizing density functional theory in this work, where the structural, elastic, electronic and mechanical anisotropy properties along with the minimum thermal conductivity are considered. SiC4 and GeC4 are semiconductor materials with direct band gaps and wide band gaps of 5.02 and 5.60 eV, respectively. The Debye temperatures of diamondyne, Si- and Ge-diamondyne are 422, 385 and 242 K, respectively, utilizing the empirical formula of the elastic modulus. Among these, Si-diamondyne has the largest mechanical anisotropy in the shear modulus and Young’s modulus, and Diamond has the smallest mechanical anisotropy in the Young’s modulus and shear modulus. The mechanical anisotropy in the Young’s modulus and shear modulus of Si-diamondyne is more than three times that of diamond as determined by the characterization of the ratio of the maximum value to the minimum value. The minimum thermal conductivity values of Si- and Ge-diamondyne are 0.727 and 0.524 W cm−1 K−1, respectively, and thus, Si- and Ge-diamondyne may be used in the thermoelectric industry.

scholarly journals Study the effect of CaCO3 nanoparticles on physical properties of biopolymer blend

2019 ◽  
Vol 16 (39) ◽  
pp. 11-22
Author(s):  
K. J. Mohammed
Keyword(s):  
Thermal Conductivity ◽  
Tensile Strength ◽  
Young’S Modulus ◽  
Polymer Blend ◽  
Young's Modulus ◽  
Antibacterial Properties ◽  
Young Modulus ◽  
Nanocomposite Films ◽  
Caco3 Nanoparticles ◽  
Mechanical Durability

Chitosan (CH) / Poly (1-vinylpyrrolidone-co-vinyl acetate) (PVP-co-VAc) blend (1:1) and nanocomposites reinforced with CaCO3 nanoparticles were prepared by solution casting method. FTIR analysis, tensile strength, Elongation, Young modulus, Thermal conductivity, water absorption and Antibacterial properties were studied for blend and nanocomposites. The tensile results show that the tensile strength and Young’s modulus of the nanocomposites were enhanced compared with polymer blend [CH/(PVP-co-VAc)] film. The mechanical properties of the polymer blend were improved by the addition of CaCO3 with significant increases in Young’s modulus (from 1787 MPa to ~7238 MPa) and tensile strength (from 47.87 MPa to 79.75 MPa). Strong interfacial bonding between the CaCO3 nanoparticles and the [CH/(PVP-co-VAc)), homogenous distribution of the nanoparticles in the polymer blend, are assistance of noticeably raised mechanical durability. The thermal conductivity of the polymer blend and CaCO3 nanocomposite films show that it decreased in the adding of nanoparticle CaCO3. The solvability measurements display that the nanocomposite has promoted water resistance. The weight gain lowered with the increase of nano CaCO3. Blending chitosan CH with (PVP-co-VAc) enhanced strength and young modules of the nanocomposites and increased the absorption of water because hydrophilic of the blended polymers films. The effect of two types of positive S.aurous and negative E. coli was studied. The results showed that the nanocomposites were effective for both types, where the activity value ranged from (12 ~ 21). The best results were found for S.aurous bacteria.

scholarly journals Polyurethane Foams for Thermal Insulation Uses Produced from Castor Oil and Crude Glycerol Biopolyols

2017 ◽  
Author(s):  
Camila S. Carriço ◽  
Thaís Fraga ◽  
Vagner E. Carvalho ◽  
Vânya M. D. Pasa
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
Young’S Modulus ◽  
Thermal Insulation ◽  
Castor Oil ◽  
Crude Glycerol ◽  
Young's Modulus ◽  
Polyurethane Foams ◽  
Co2 Production ◽  
Blowing Agent

Rigid polyurethane foams were synthesized using a renewable polyol from the simple physical mixture of castor oil and crude glycerol. The effect of the catalyst and blowing agent in the foams properties was evaluated. The use of physical blowing agent (cyclopentane and n-pentane) allowed obtaining foams with smaller cells in comparison with the foams produced with a chemical blowing agent (water). The increase of water content caused a decrease of density, thermal conductivity, compressive strength and Young's modulus, which indicates that the increment of CO2 production contributes to the formation of larger cells. Higher amount of catalyst in the foam formulations caused a slight density decrease and an increase small significance of thermal conductivity, compressive strength and Young's modulus values. These green foams presented properties that indicate a great potential to be used as thermal insulation, as density (23 - 41 kg m-3), thermal conductivity (0.0128 – 0.0207 W m-1 K-1), compressive strength (45 - 188 kPa) and Young's modulus (3 - 28 kPa). These biofoams are also environmental friendly alternatives and can aggregate revenue to biodiesel industry, contributing for reduction of this fuel prices.

scholarly journals Effect of Defects on the Mechanical and Thermal Properties of Graphene

Nanomaterials ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 347 ◽  
Author(s):  
Maoyuan Li ◽  
Tianzhengxiong Deng ◽  
Bing Zheng ◽  
Yun Zhang ◽  
Yonggui Liao ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Thermal Properties ◽  
Strain Rate ◽  
Young’S Modulus ◽  
Fracture Strength ◽  
Fracture Strain ◽  
Young's Modulus ◽  
Pristine Graphene ◽  
Mechanical And Thermal Properties

In this study, the mechanical and thermal properties of graphene were systematically investigated using molecular dynamic simulations. The effects of temperature, strain rate and defect on the mechanical properties, including Young’s modulus, fracture strength and fracture strain, were studied. The results indicate that the Young’s modulus, fracture strength and fracture strain of graphene decreased with the increase of temperature, while the fracture strength of graphene along the zigzag direction was more sensitive to the strain rate than that along armchair direction by calculating the strain rate sensitive index. The mechanical properties were significantly reduced with the existence of defect, which was due to more cracks and local stress concentration points. Besides, the thermal conductivity of graphene followed a power law of λ~L0.28, and decreased monotonously with the increase of defect concentration. Compared with the pristine graphene, the thermal conductivity of defective graphene showed a low temperature-dependent behavior since the phonon scattering caused by defect dominated the thermal properties. In addition, the corresponding underlying mechanisms were analyzed by the stress distribution, fracture structure during the deformation and phonon vibration power spectrum.

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