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.

scholarly journals Molecular Dynamics Study on the Deformation Behaviors of Nanostructures in the Demolding Process of Micro-Injection Molding

Polymers ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 470 ◽  
Author(s):  
Can Weng ◽  
Jin Yang ◽  
Dongjiao Yang ◽  
Bingyan Jiang
Keyword(s):  
Molecular Dynamics ◽  
Injection Molding ◽  
Mold Insert ◽  
Adhesion Energy ◽  
Molded Parts ◽  
Replication Quality ◽  
Deformation Behaviors ◽  
Dynamics Simulations ◽  
Polymer Nanostructure

Polymer parts with nanostructures have broad applications, possessing excellent optical, electrochemical, biological, and other functions. Injection molding technology is one of the main methods for mass production of polymer parts with various shapes and sizes. The demolding process is vital to the replication quality of molded parts with nanostructures. For this study, molecular dynamics simulations of polypropylene (PP), polymethyl methacrylate (PMMA), and cycloolefin copolymer (COC) were conducted for the demolding process. The average velocity, density distribution, adhesion energy, and demolding resistance were introduced to analyze the deformation behaviors of polymer nanostructure from a nickel nano-cavity with an aspect ratio of 2:1. The shoulders of nanostructures were firstly separated from the nickel mold insert in the simulation. Under the external demolding force of 0.07 nN, PP and PMMA could be successfully demolded with some deformations, while COC could not be completely demolded due to the greater adhesion energy between COC and Ni. It was found that the maximum adhesion energy occurred in the separation process between the shoulder of the nanostructure and Ni and the huge adhesion energy was the main cause of demolding defects. The velocity difference of the whole polymer layer and polymer nanostructure was further analyzed to explain the nanostructure deformation. In order to improve the quality of demolding, the external force applied on polymers should be properly increased.

scholarly journals Experimental Investigation and Molecular Dynamics Simulation on the Anti-Adhesion Behavior of Alkanethiols on Nickel Insert in Micro Injection Molding

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1834
Author(s):  
Can Weng ◽  
Jiachen Chen ◽  
Jin Yang ◽  
Mingyong Zhou ◽  
Bingyan Jiang
Keyword(s):  
Molecular Dynamics ◽  
Injection Molding ◽  
Md Simulation ◽  
Mold Insert ◽  
Dynamics Simulation ◽  
Injection Molding Process ◽  
Molding Process ◽  
Micro Injection Molding ◽  
Adhesion Behavior ◽  
Self Assembled

Due to the adhesion between the polymer melt and nickel (Ni) mold insert in the micro injection molding process, deformation defects frequently occur when the microstructures are demolded from the insert. In this study, self-assembled alkanethiols were applied to modify the surface of Ni mold insert to reduce its surface energy. Experimental trials were undertaken to explore the effect of alkanethiols coating on the replication quality. After that, molecular dynamics (MD) simulation was then used to investigate the adhesion behavior between the self-assembled coating and polypropylene (PP) by establishing three different types of alkanethiol material. The interaction energy, the potential energy change and radial distribution function were calculated to study the anti-adhesion mechanism. Experimental results show that all the three coatings can effectively decrease the adhesion and therefore promote the replication fidelity. It is demonstrated in MD simulation that the adhesion mainly comes from the van der Waals (vdW) force at the interface. The arrangement of sulfur atom on the Ni surface results in different absorbing behaviors. Compared with that of the PP–Ni interface, the interfacial energy and adhesion work after surface treatment is significantly reduced.

scholarly journals Investigation of Interface Thermal Resistance between Polymer and Mold Insert in Micro-Injection Molding by Non-Equilibrium Molecular Dynamics

Polymers ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2409
Author(s):  
Can Weng ◽  
Jiangwei Li ◽  
Jun Lai ◽  
Jiangwen Liu ◽  
Hao Wang
Keyword(s):  
Heat Transfer ◽  
Molecular Dynamics ◽  
Injection Molding ◽  
Thermal Resistance ◽  
Mold Insert ◽  
Micro Injection Molding ◽  
Interface Resistance ◽  
Interface Thermal Resistance ◽  
Packing Pressure ◽  
Non Equilibrium Molecular Dynamics

Micro-injection molding has attracted a wide range of research interests to fabricate polymer products with nanostructures for its advantages of cheap and fast production. The heat transfer between the polymer and the mold insert is important to the performance of products. In this study, the interface thermal resistance (ITR) between the polypropylene (PP) layer and the nickel (Ni) mold insert layer in micro-injection molding was studied by using the method of non-equilibrium molecular dynamics (NEMD) simulation. The relationships among the ITR, the temperature, the packing pressure, the interface morphology, and the interface interaction were investigated. The simulation results showed that the ITR decreased obviously with the increase of the temperature, the packing pressure and the interface interaction. Both rectangle and triangle interface morphologies could enhance the heat transfer compared with the smooth interface. Moreover, the ITR of triangle interface was higher than that of rectangle interface. Based on the analysis of phonon density of states (DOS) for PP-Ni system, it was found that the mismatch between the phonon DOS of the PP atoms and Ni atoms was the main cause of the interface resistance. The frequency distribution of phonon DOS also affected the interface resistance.

Nano-Grooving on Copper by Nano-Milling and Nano-Cutting

2011 ◽  
Vol 325 ◽  
pp. 576-581 ◽  
Author(s):  
D.D. Cui ◽  
Kausala Mylvaganam ◽  
Liang Chi Zhang
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
High Speed ◽  
Dynamics Simulation ◽  
Smooth Surfaces ◽  
High Quality ◽  
Nano Scale

This paper uses the molecular dynamics simulation to investigate the quality of nano-scale grooving on mono-crystalline copper by high-speed nano-milling and nano-cutting. The results reveal that nano-milling produces a high-quality nano-groove with smooth surfaces in comparison with a nano-cutting. It is also interesting to note that the machined workpiece subsurface can be free from dislocations.

Molecular dynamics simulation study on ablation of silicon by water-jet-guided laser

2016 ◽  
Vol 231 (6) ◽  
pp. 1217-1225 ◽  
Author(s):  
Weiguo Zhou ◽  
Keyu Gong ◽  
Jie Wan ◽  
Lulu Quan ◽  
Yuchuan Chu ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Femtosecond Laser ◽  
Water Jet ◽  
Dynamics Simulation ◽  
Jet Cooling ◽  
Simulation Results ◽  
Weber Potential ◽  
Thermal Affected Zone

Stillinger–Weber potential and Z-layer energy model were adopted in molecular dynamics simulation to study the ablation of silicon by water-jet-guided femtosecond laser, and comparison was made by ablating silicon with or without water-jet cooling in our simulations. Simulation results indicated that with water-jet cooling, the thermal-affected zone could be reduced in area, and the peak of density could disappear more quickly. It was therefore concluded that water-jet-guided laser could be used to considerably improve the ablation quality of silicon.

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