scholarly journals Orientation and Dispersion Evolution of Carbon Nanotubes in Ultra High Molecular Weight Polyethylene Composites under Extensional-Shear Coupled Flow: A Dissipative Particle Dynamics Study

Polymers ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 154 ◽  
Author(s):  
Junxia Wang ◽  
Changlin Cao ◽  
Xiaochuan Chen ◽  
Shijie Ren ◽  
Yu Chen ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Molecular Weight ◽  
High Molecular Weight ◽  
Dissipative Particle Dynamics ◽  
Mean Square Displacement ◽  
Particle Dynamics ◽  
Distribution Functions ◽  
Coupled Flow ◽  
Uhmwpe Composites ◽  
Ultra High Molecular Weight

The property of carbon nanotubes (CNTs)-based composites are significantly dependent on the orientation and dispersion evolution of CNTs in the polymer matrix. In this work, the dissipative particle dynamics (DPD) simulations are employed to discover the orientation and dispersion evolution of CNTs in ultra–high molecular weight polyethylene (UHMWPE) under extensional–shear coupled flow conditions for the first time. In this paper, we investigate the roles of the increasing extensional-shear coupled rate in morphology of CNTs/UHMWPE composites by varying CNTs concentration and observe that the system under consideration lies in the same evolution morphologies. When comparing our results for various morphologies, we notice that the orientation is affected more significantly by changing the extensional-shear coupled rates. A good alignment appears with an increase of extensional-shear coupled rates, which transform it into ordered morphology. In addition, a higher extensional-shear coupled rate does not necessarily contribute to better dispersion even though CNTs concentration varies, as shown by the mean square displacement (MSD) and the relative concentration distribution functions of CNTs in CNTs/UHMWPE composites.

scholarly journals A Dissipative Particle Dynamics Study of Flow Behaviors in Ultra High Molecular Weight Polyethylene/Polyamide 6 Blends Based on Souza-Martins Method

Polymers ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1275 ◽  
Author(s):  
Wang ◽  
Li ◽  
Cao ◽  
ShijieRen ◽  
Yu
Keyword(s):  
Molecular Weight ◽  
Shear Flow ◽  
High Molecular Weight ◽  
Flow Behavior ◽  
Dissipative Particle Dynamics ◽  
Polyamide 6 ◽  
Particle Dynamics ◽  
Simple Shear Flow ◽  
Coupled Flow ◽  
Ultra High Molecular Weight

This paper presents our study on the use of dissipative particle dynamics (DPD) simulations to discover the flow behavior in ultra high molecular weight polyethylene/polyamide 6 (UHMWPE/PA6) blends associated with extensional-shear coupled flow, based on the Souza-Martins method, for the first time. By way of simulations, we aimed at investigating the mesoscopic morphology and alignment behavior in response to extensional-shear coupled flow, in comparison with simple shear flow and simple extensional flow. Our results reveal that the aggregation of polymers is noticeable under zero flow, as expected. Within the considered range of extensional-shear coupled rates, the morphology transforms from micelle-like clusters to a chain-like network structure by increasing coupled rates from 0.01 to 2.0. Furthermore, it shows a linear distribution along the flow direction at a high coupled rate. It can be concluded that the flow behaviors in UHMWPE/PA6 blends are significantly impacted by extensional-shear coupled rates. The orientation behavior induced by extensional-shear coupled flow is more obvious than shear flow, even though flow variations and mass fractions yield less effects on the distribution behaviors of UHMWPE/PA6 blends. The DPD results are verified by mean square displacement (MSD) as a function of simulation time and relative concentration distribution along Z direction.

MECHANICAL AND TRIBOTECHNICAL PROPERTIES OF MULTICOMPONENT SOLID LUBRICANT COMPOSITES BASED ON ULTRA HIGH MOLECULAR WEIGHT POLYETHYLENE

1970 ◽  
Vol 61 (11) ◽  
Author(s):  
Sergey V. Panin ◽  
Vladislav О. Alexenko ◽  
Lyudmila А. Kornienko ◽  
Dmitry G. Buslovich ◽  
Natalya N. Valentyukevich
Keyword(s):  
Molecular Weight ◽  
Wear Resistance ◽  
High Molecular Weight ◽  
Carbon Fibers ◽  
Friction Surface ◽  
Solid Lubricant ◽  
Permolecular Structure ◽  
Uhmwpe Composites ◽  
Ultra High Molecular Weight ◽  
Short Carbon

Multicomponent composites with ultra-high molecular weight polyethylene (UHMWPE) matrix reinforced by short carbon fibers (CF) and filled with solid lubricant particles of finely dispersed polytetrafluoroethylene (PTFE) have been studied. It is shown that simultaneous loading of two kinds of microfillers (enforcing and solid lubricant) ensures increasing both mechanical properties (elastic modulus, yield point, shore D hardness) and wear resistance of three-component UHMWPE composites at variation of triboloading conditions. It is shown that at moderate sliding velocity (V = 0.3 m/s) and load (P = 60 N) the rational composition providing maximum wear resistance under dry sliding friction is “UHMWPE + 5 wt. % fluorolite + 5 wt. % CF” (wear resistance is doubled). The latter results from the pattern of the formed permolecular structure and friction surface material response onto tribotechnical loading (due to formation of transfer film).Under severe tribotesting conditions (P = 140 N × V = 0.5 m/s) the two-fold increase in wear resistance demonstrates the composite “UHMWPE + 5 wt. % fluorolite + 10 wt. % CF”. This effect is mostly governed by enforcing action of short carbon fibers. The mechanism of this improvement might be explained in the following way. Friction heating induced increase of the temperature gives rise to local melting and surface layer plasticization. Presence of enforcing fibers ensures better protection of the friction surface from combined action of compressive and shear forces transferred from rotating steel counterface. Friction coefficient, topography of wear track surfaces and wear mechanisms of multicomponent UHMWPE composites are discussed taking into account the data on permolecular structure formation and the temperature in the tribocontact zone.  

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