scholarly journals Molecular Dynamics Simulation-Based Study on Enhancing Thermal Properties of Graphene-Reinforced Thermoplastic Polyurethane Nanocomposite for Heat Exchanger Materials

2020 ◽  
Author(s):  
Animesh Talapatra ◽  
Debasis Datta
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Glass Transition ◽  
Thermal Properties ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Md Simulation ◽  
Thermoplastic Polyurethane ◽  
Simulation Based ◽  
Simulation Results

Molecular dynamics (MD) simulation-based development of heat resistance nanocomposite materials for nanoheat transfer devices (like nanoheat exchanger) and applications have been studied. In this study, MD software (Materials Studio) has been used to know the heat transport behaviors of the graphene-reinforced thermoplastic polyurethane (Gr/TPU) nanocomposite. The effect of graphene weight percentage (wt%) on thermal properties (e.g., glass transition temperature, coefficient of thermal expansion, heat capacity, thermal conductivity, and interface thermal conductance) of Gr/TPU nanocomposites has been studied. Condensed-phase optimized molecular potentials for atomistic simulation studies (COMPASS) force field which is incorporated in both amorphous and forcite plus atomistic simulation modules within the software are used for this present study. Layer models have been developed to characterize thermal properties of the Gr/TPU nanocomposites. It is seen from the simulation results that glass transition temperature (Tg) of the Gr/TPU nanocomposites is higher than that of pure TPU. MD simulation results indicate that addition of graphene into TPU matrix enhances thermal conductivity. The present study provides effective guidance and understanding of the thermal mechanism of graphene/TPU nanocomposites for improving their thermal properties. Finally, the revealed enhanced thermal properties of nanocomposites, the interfacial interaction energy, and the free volume of polymer nanocomposites are examined and discussed.

scholarly journals Thermal and thermodynamic characterization of a dye powder from liquid turmeric extracts by spray drying

2016 ◽  
Vol 69 (1) ◽  
pp. 7845-7854 ◽  
Author(s):  
Aura Yazmin Coronel Delgado ◽  
Héctor José Ciro Velásquez ◽  
Diego Alonso Restrepo Molina
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Glass Transition ◽  
Thermal Properties ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Mass Loss ◽  
Spray Drying ◽  
Transient Flow ◽  
Sorption Isotherms

This study aimed to evaluate the thermodynamic properties of sorption isotherms and glass transition temperature (Tg) and the thermal properties of a dye powder obtained from turmeric extracts using spray drying. The sorption isotherms were evaluated at 15, 25 and 35 °C using the dynamic gravimetric method, wherein the isotherm data of the experiment were fit to GAB and BET models. Likewise, the Tg was measured using differential scanning calorimetry (DSC). Thermogravimetric analysis (TGA) was used to determine the mass loss, and the thermal properties (heat capacity, diffusivity and thermal conductivity) were determined using transient flow method. The results demonstrated that the GAB model best fit the adsorption data. The DSC analysis presented a glass transition temperature of 65.35 °C and a loss of volatiles at 178.07 °C. The TGA analysis indicated a considerable mass loss starting at 193 °C, resulting in degradation of the product. The thermal properties demonstrated a heat capacity of 2.45 J/g °C, a thermal conductivity of 0.164 ± 0.001 W/mK and a thermal diffusivity of 8.7x10-8 ± 0.000 m2/s.

Influence of Electron Beam Irradiation and Step-Crosslinking Process on Solvent Penetration and Thermal Properties of Natural Rubber Vulcanizates

2005 ◽  
Vol 13 (1) ◽  
pp. 93-103 ◽  
Author(s):  
M. Madani ◽  
M.M. Badawy
Keyword(s):  
Thermal Conductivity ◽  
Glass Transition ◽  
Thermal Properties ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Cross Linking ◽  
Beam Irradiation ◽  
Cross Link ◽  
Link Density ◽  
Cross Link Density

The influence of both beam irradiation and step cross-linking on high abrasion furnace (HAF) carbon black loaded natural rubber (NR) vulcanizates are reported. With irradiation, a higher cross-link density, ν, thermal conductivity, λ, and glass transition temperature, Tg, have been observed for such materials, as compared with the un-irradiated ones. There is also a decreased specific heat capacity, Cp. Meanwhile, the step cross-linking process has a slight effect on the cross-link density, glass transition temperature and thermal properties of these composites. The results of such changes in thermal conductivity are explained with the help of a simple modified model.

Molecular Dynamics Simulation on Compatibility and the Glass Transition Temperature of HTPB/Plasticizer Blends

2013 ◽  
Vol 718-720 ◽  
pp. 136-140 ◽  
Author(s):  
Lu Xia Yang ◽  
Lin Yu Mei ◽  
Yan Hua Lan ◽  
Li Qiong Liao ◽  
Yi Zheng Fu
Keyword(s):  
Molecular Dynamics ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Specific Volume ◽  
Md Simulation ◽  
Dibutyl Phthalate ◽  
Dioctyl Phthalate ◽  
Dynamics Simulation ◽  
Solubility Parameters

By means of full atomistic molecular dynamics (MD) simulation, the solubility parameters for hydroxyl-terminated polybutadiene (HTPB), dioctyl sebacate (DOS), dioctyl adipate (DOA), dibutyl phthalate (DBP), dioctyl phthalate (DOP), nitrated esters nitroglycerine (NG) and diethylene glycol dinitrate (DEGDN) are calculated and the results are in agreement with the literature values. Furthermore, in order to reveal the HTPB/plasticizer blend property, the specific volume vs. temperature curves of the blend systems are simulated by employing MD simulation to obtain the glass transition temperature (Tg). From the specific volume vs. temperature curve, the Tg of HTPB, HTPB/DOS, HTPB/DOA, HTPB/DBP, HTPB/DOP, HTPB/NG and HTPB/DEGDN are 197.54, 176.30, 183.11, 189.27,187.40, 200.03 and 205.31 K, respectively. It should be pointed out that as for HTPB and DOS, DOA, DBP, DOP, the solubility parameters are similar and there is only one glass transition of the blend system, these indicate that these studied blend systems are miscible, but HTPB/NG and HTPB/DEGDN are not miscible.

A Novel Poly(Ionic Liquid) as the Thermal Insulating Material

2020 ◽  
Vol 13 (3) ◽  
pp. 241-247
Author(s):  
Wenxin Wei ◽  
Guifeng Ma ◽  
Hongtao Wang ◽  
Jun Li
Keyword(s):  
Thermal Conductivity ◽  
Ionic Liquid ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Flame Resistance ◽  
Insulating Material ◽  
Low Thermal Conductivity ◽  
Thermal Insulating ◽  
Poly Ionic Liquid

Objective: A new poly(ionic liquid)(PIL), poly(p-vinylbenzyltriphenylphosphine hexafluorophosphate) (P[VBTPP][PF6]), was synthesized by quaternization, anion exchange reaction, and free radical polymerization. Then a series of the PIL were synthesized at different conditions. Methods: The specific heat capacity, glass-transition temperature and melting temperature of the synthesized PILs were measured by differential scanning calorimeter. The thermal conductivities of the PILs were measured by the laser flash analysis method. Results: Results showed that, under optimized synthesis conditions, P[VBTPP][PF6] as the thermal insulator had a high glass-transition temperature of 210.1°C, high melting point of 421.6°C, and a low thermal conductivity of 0.0920 W m-1 K-1 at 40.0°C (it was 0.105 W m-1 K-1 even at 180.0°C). The foamed sample exhibited much low thermal conductivity λ=0.0340 W m-1 K-1 at room temperature, which was comparable to a commercial polyurethane thermal insulating material although the latter had a much lower density. Conclusion: In addition, mixing the P[VBTPP][PF6] sample into polypropylene could obviously increase the Oxygen Index, revealing its efficient flame resistance. Therefore, P[VBTPP][PF6] is a potential thermal insulating material.

Influence of Carbon Nanotube Aspect Ratio on Glass Transition Temperature of Polymers: A Molecular Dynamics Simulation Study

2015 ◽  
Vol 817 ◽  
pp. 797-802 ◽  
Author(s):  
Cai Jiang ◽  
Jian Wei Zhang ◽  
Shao Feng Lin ◽  
Su Ju ◽  
Da Zhi Jiang
Keyword(s):  
Molecular Dynamics ◽  
Glass Transition ◽  
Carbon Nanotube ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Aspect Ratio ◽  
Epoxy Resin ◽  
Md Simulations ◽  
Diglycidyl Ether ◽  
Dynamics Simulation

Molecular dynamics (MD) simulations on three single walled carbon nanotube (SWCNT) reinforced epoxy resin composites were conducted to study the influence of SWCNT type on the glass transition temperature (Tg) of the composites. The composite matrix is cross-linked epoxy resin based on the epoxy monomers bisphenol A diglycidyl ether (DGEBA) cured by diaminodiphenylmethane (DDM). MD simulations of NPT (constant number of particles, constant pressure and constant temperature) dynamics were carried out to obtain density as a function of temperature for each composite system. The Tg was determined as the temperature corresponding to the discontinuity of plot slopes of the densityvsthe temperature. In order to understand the motion of polymer chain segments above and below the Tg, various energy components and the MSD at various temperatures of the composites were investigated and their roles played in the glass transition process were analyzed. The results show that the Tg of the composites increases with increasing aspect ratio of the embedded SWCNT

Thermal Properties of Bi2O3-B2O3-ZnO Glass System

2006 ◽  
Vol 510-511 ◽  
pp. 578-581 ◽  
Author(s):  
Yu Jin Kim ◽  
Seong Jin Hwang ◽  
Hyung Sun Kim
Keyword(s):  
Glass Transition ◽  
Thermal Properties ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Lead Oxide ◽  
Lead Free ◽  
Oxide Glasses ◽  
Glass Formation Region ◽  
Formation Region ◽  
Lower Glass Transition Temperature

Oxide glasses having lower glass transition temperature are widely used in electric devices. The oxide glasses usually contain lead oxide. Recently, lead oxide glasses have been replaced with lead-free oxide glasses because of the environmental pollution. We investigated the thermal properties and the glass formation region in the Bi2O3-B2O3-ZnO ternary system. The results showed that the ratio of Tg/Tl of the bismate glasses is around 0.55, which is lower than the value of ratio 0.67, the two-third rule (Tg/ Tl=2/3)

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