scholarly journals The Adhesion and Diffusion of Saturate, Asphaltene, Resin and Aromatic (SARA) Molecules on Oxygenated and Hydrogenated Carbon Nanotubes (CNTs)

2021 ◽  
Vol 6 (9) ◽  
pp. 123
Author(s):  
Mehdi Shishehbor ◽  
Hadi S. Esmaeeli ◽  
M. Reza Pouranian
Keyword(s):  
Carbon Nanotubes ◽  
Interfacial Adhesion ◽  
Asphalt Binder ◽  
Adhesion Energy ◽  
Dynamics Simulation ◽  
Hydroxyl Groups ◽  
Reactive Molecular Dynamics ◽  
Cnts Surface ◽  
And Diffusion ◽  
Diffusion Properties

The interfacial adhesion between asphalt binder and carbon nanotubes (CNTs) depends on many nanoscopic properties such as diffusion of SARA molecules on CNTs surface. Functionalization of CNTs with Oxygens (O=CNTs), hydroxyl groups (HO–CNTs), and hydrogens (H–CNTs) has been an effective way to modify the surface properties of CNTs and ultimately the macroscopic properties of the CNT-composites. This paper presents the effect of different dosages of oxygenated and hydrogenated CNTs on the adhesion and diffusion of SARA molecules on CNTs’ surfaces. First, reactive molecular dynamics simulation is used to oxygenate and hydrogenate CNTs up to a certain dosage. Next, it is employed to model the interaction and diffusion of SARA molecules with the functionalized CNTs. We employ the steer molecular dynamic (SMD) and Einstein formula to calculate the adhesion and diffusion properties. The results demonstrate that hydrogenation has little effect on the adhesion energy, while oxygenation can increase adhesion energy up to 100% for 25% dosage. The diffusion coefficient dramatically drops for both oxygenated and hydrogenated CNTs, with lower values for the latter. We observe that for hydrogenated and oxygenated CNTs at different dosages, asphaltene, resin, aromatic, and saturate molecules have the highest to lowest values, respectively.

scholarly journals Molecular Dynamics Simulation on the Influences of Nanostructure Shape, Interfacial Adhesion Energy, and Mold Insert Material on the Demolding Process of Micro-Injection Molding

Polymers ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 1573 ◽  
Author(s):  
Jin Yang ◽  
Can Weng ◽  
Jun Lai ◽  
Tao Ding ◽  
Hao Wang
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Injection Molding ◽  
Interfacial Adhesion ◽  
Mold Insert ◽  
Adhesion Energy ◽  
Dynamics Simulation ◽  
Micro Injection Molding ◽  
Interfacial Adhesion Energy

In micro-injection molding, the interaction between the polymer and the mold insert has an important effect on demolding quality of nanostructure. An all-atom molecular dynamics simulation method was performed to study the effect of nanostructure shape, interfacial adhesion energy, and mold insert material on demolding quality of nanostructures. The deformation behaviors of nanostructures were analyzed by calculating the non-bonded interaction energies, the density distributions, the radii of gyration, the potential energies, and the snapshots of the demolding stage. The nanostructure shape had a direct impact on demolding quality. When the contact areas were the same, the nanostructure shape did not affect the non-bonded interaction energy at PP-Ni interface. During the demolding process, the radii of gyration of molecular chains were greatly increased, and the overall density was decreased significantly. After assuming that the mold insert surface was coated with an anti-stick coating, the surface burrs, the necking, and the stretching of nanostructures were significantly reduced after demolding. The deformation of nanostructures in the Ni and Cu mold inserts were more serious than that of the Al2O3 and Si mold inserts. In general, this study would provide theoretical guidance for the design of nanostructure shape and the selection of mold insert material.

Molecular Dynamics Simulation to Investigate the Adhesion and Diffusion of Asphalt Binder on Aggregate Surfaces

2019 ◽  
Vol 2673 (4) ◽  
pp. 500-512 ◽  
Author(s):  
Zhao Du ◽  
Xingyi Zhu
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Asphalt Binder ◽  
Asphalt Mixture ◽  
Dynamics Simulation ◽  
Main Role ◽  
Mineral Surfaces ◽  
Mineral Surface ◽  
And Diffusion ◽  
Mineral Aggregates

Asphalt-aggregate interface properties are considered to play a crucial role in asphalt mixture. To better understand the detailed binding mechanism, the present study analyzed the adhesion and diffusion of asphalt binder on mineral surfaces at a nanoscale based on molecular dynamics simulation. A 12-component AAA-1 asphalt model and five oxide models were generated to represent asphalt binder and mineral aggregates, respectively. The effectiveness of these models was validated by comparing the physical properties of the model with the values reported in the literature. The binding energy and diffusion coefficient obtained were examined to characterize the adhesion and diffusion of asphalt on different mineral surfaces. The results indicated that van der Waals energy played the main role in forming the strong physisorption of asphalt on the mineral surface. Among all four fractions of asphalt, asphaltene made a great contribution to the adhesion of asphalt on the mineral surface. It was also found that the work of adhesion between asphalt and five oxides ranked MgO > CaO > Al2O3 > Fe2O3 > SiO2. The content of MgO and CaO in mineral aggregates can be further adopted as an index to evaluate and classify mineral aggregates during asphalt mixture design. Meanwhile, asphalt mobility does not entirely rely on the molecular mass but also depends strongly on the medium it adsorbed into and interaction energy. This work provides a fundamental understanding of the adhesion and diffusion of asphalt binder on the mineral aggregate surface at the atomistic scale.

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