Surface induced crystallization of polymeric nano-particles: effect of surface roughness

2017 ◽  
Vol 204 ◽  
pp. 307-330 ◽  
Author(s):  
Ahmad Jabbarzadeh ◽  
Xin Chen
Keyword(s):  
Smooth Surface ◽  
Crystallization Rate ◽  
Crystal Growth Rate ◽  
Nano Particles ◽  
Polymeric System ◽  
Wenzel State ◽  
Polymeric Particle ◽  
Dynamics Simulations ◽  
Induced Crystallization ◽  
Effect Of Surface

Molecular dynamics simulations are conducted to study the crystallization of a polymeric system as a drop in an isolated state and on a surface. It is shown that crystallization kinetics for the polymeric system as a particle on a smooth surface is much faster than in the isolated form. We show however that as the surface becomes rough the crystallization rate of the polymeric particle decreases. The effect of roughness was compared for two cases of a polymer drop, partially (Wenzel state) and fully (fully confined) wetting the cavities on a rough surface. In both cases it was observed that crystallization was slower than that on a smooth surface, and crystal growth rate was decreased by increasing the characteristic roughness ratio. The crystallization on rough surfaces was still faster than that of the isolated polymer drop.

scholarly journals Effect of Surface Nano-Texturing on Wetting Properties: Molecular Dynamics Study

2020 ◽  
Vol 65 (9) ◽  
pp. 817
Author(s):  
M. Aleksandrovych ◽  
G. Castanet ◽  
S. Burian ◽  
F. Lemoine ◽  
D. Lacroix ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Smooth Surface ◽  
Substrate Surface ◽  
Equilibrium Shape ◽  
Solid Substrate ◽  
Silicon Substrates ◽  
Wetting Properties ◽  
Flat Substrate ◽  
Dynamics Simulations ◽  
Effect Of Surface

Molecular dynamics simulations describing the equilibrium shape of a nanodroplet located on the solid substrate are presented for the cases of a “cylindrical water droplet” on silicon substrates. Several examples of the structuration of the solid substrate surface are simulated, i.e.: atomistic flat substrate and substrates with ordered nanopillars and nanopores. The adhesives forces between molecules of the substrate and the fluid are modified to change the wettability. Three wetting configurations are considered in this work for the smooth surface: (i) hydrophilic (0 = 30∘), (ii) hydrophobic (0 = 136∘), and (iii) an intermediate regime (0 = 80∘). Further, the dependence of the wetting angle as a function of the surface state is studied in details for the above-mentioned configurations.

Effect of surface morphology on laser-induced crystallization of amorphous silicon thin films

2013 ◽  
Author(s):  
Lu Huang ◽  
Jing Jin ◽  
Guohua Wang ◽  
Weimin Shi ◽  
Weiguang Yang ◽  
...  
Keyword(s):  
Thin Films ◽  
Surface Morphology ◽  
Amorphous Silicon ◽  
Silicon Thin Films ◽  
Induced Crystallization ◽  
Effect Of Surface

Elastomer Structures and ‘Cold Crystallization’

1979 ◽  
Vol 52 (1) ◽  
pp. 207-212 ◽  
Author(s):  
M. Bruzzone ◽  
E. Sorta
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Melting Point ◽  
Natural Rubber ◽  
Crystallization Rate ◽  
Cold Crystallization ◽  
Structural Defects ◽  
Strain Induced Crystallization ◽  
Induced Crystallization

Abstract In a great number of applications an ideal elastomer should satisfy, to a certain extent, both of the following requirements: (1) nearly instantaneous crystallization upon application of strain (strain induced crystallization) and (2) slow or no crystallization when cooled at the temperature of maximum crystallization rate (cold induced crystallization). A noteworthy case of (2) is elastomer crystallization in a strained state. The connection between the points (1) and (2) has not been clearly understood up to now, but it is known that some crystallizable elastomers fulfil the requirements of both (1) and (2) better than others. From an experimental point of view, cold induced crystallization kinetics are substantially easier to measure than those of very fast strain induced crystallization. The phenomenon of cold induced crystallization in natural rubber, NR, has been known since the very beginning of elastomer technology and the tendency of natural rubber to crystallize by cooling has been overcome by crosslinking it with sulphur (vulcanization) without impairing its ability to crystallize by stretching (Goodyear, 1836). The synthesis of cis-polyisoprenes (IR) and cis-polybutadiene (BR) of different microstructural purity (different cis content) gave the possibility of changing the crystallization rate. It has also been reported that the very fast cold crystallization of trans-polypentenamer (TPA) could be reduced by lowering the trans content. The same fact had been observed earlier for trans-polychloroprene. There is a general agreement in postulating that the reduction of the crystallization rate, obtained either by cross-linking or by chain regularity reduction, can be linked with the lowering of the melting point. In both cases the low level of structural defects introduced in the chains does not affect the glass transition temperature in such a way as to vary the crystallization rate. The aim of this paper is to emphasize the importance of the variations of the glass transition temperature and melting point on the elastomeric cold crystallization rate and the way these may be used in planning new elastomer structures.

Flow induced crystallization of LDPE nanocomposites: A rheological and morphological characterization

e-Polymers ◽  
2011 ◽  
Vol 11 (1) ◽  
Author(s):  
Fiorenza Azzurri ◽  
Paola Stagnaro ◽  
Lucia Conzatti ◽  
Dario Cavallo ◽  
Luca Repetto ◽  
...  
Keyword(s):  
Shear Flow ◽  
Flow Direction ◽  
Crystallization Rate ◽  
Morphological Characterization ◽  
External Flow ◽  
Nucleation Density ◽  
Induced Crystallization ◽  
Flow Induced Crystallization ◽  
Nucleating Effect

AbstractThe flow induced crystallization behaviour of a LDPE:PE-g-MA:D72T 90:9:1 nanocomposite has been investigated by in-situ Rheo-SALS technique and data have been compared with those obtained from a reference LDPE:PE-g-MA 90:9 sample. Rheo SALS results, confirming thermal analysis findings, indicate that under mild shear flow fields the organoclay exhibits a negligible nucleating effect. Both nucleation density and, as a consequence, crystallization rate, are not appreciably affected by the application of external flow field for both the examined systems, revealing that no evident synergic effects between the organoclay and the shear flow are present. On the other hand, Rheo SALS analysis indicates that the nanocomposite submitted to flow exhibits a higher level of crystal orientation. TEM morphological analyses support this observation suggesting that the orientation of the nanofiller along the flow direction templates the growth of oriented crystals.

scholarly journals Surface Energy-Controlled Self-Collapse of Carbon Nanotube Bundles With Large and Reversible Volumetric Deformation

2013 ◽  
Vol 80 (4) ◽  
Author(s):  
Yuan Cheng ◽  
Nicola Maria Pugno ◽  
Xinghua Shi ◽  
Bin Chen ◽  
Huajian Gao
Keyword(s):  
Carbon Nanotubes ◽  
Molecular Dynamics ◽  
Carbon Nanotube ◽  
Surface Energy ◽  
Nanotube Bundles ◽  
Volumetric Deformation ◽  
Equilibrium Configurations ◽  
Simulation Results ◽  
Dynamics Simulations ◽  
Effect Of Surface

Molecular dynamics simulations are performed to investigate the effect of surface energy on equilibrium configurations and self-collapse of carbon nanotube bundles. It is shown that large and reversible volumetric deformation of such bundles can be achieved by tuning the surface energy of the system through an applied electric field. The dependence of the bundle volume on surface energy, bundle radius, and nanotube radius is discussed via a dimensional analysis and determined quantitatively using the simulation results. The study demonstrates potential of carbon nanotubes for applications in nanodevices where large, reversible, and controllable volumetric deformations are desired.

The Effect of Surface Texture on Thermal Sensation and Comfort

2017 ◽  
Author(s):  
Han Zhang ◽  
Alan Hedge
Keyword(s):  
Thermal Comfort ◽  
Spatial Patterns ◽  
Surface Texture ◽  
Smooth Surface ◽  
Thermal Sensation ◽  
Electronic Devices ◽  
Material Surface ◽  
Tablet Computer ◽  
Physical Sensation ◽  
Effect Of Surface

The study investigated how the material roughness of a tablet computer surface can affect thermal sensation and comfort of users fingers and palms at different surface temperatures. Three levels of pattern spacing were tested, and it was shown that rough material surface provided higher thermal comfort comparing to a smooth surface. In addition, the surface temperature of the material also moderates participants′ physical sensation of the roughness of the materials. The results of the study have shown evidences of the potentials to use materials with spatial patterns to improve thermal comfort while dissipating heat from electronic devices.

A Novel Back-Reflecting UV-Assisted Metal-Induced Crystallization of Silicon on Glass

2001 ◽  
Vol 664 ◽  
Author(s):  
Leila Rezaee ◽  
Shamsoddin Mohajerzadeh ◽  
Ali Khakifirooz ◽  
Saber Haji ◽  
Ebrahim Asl Soleimani
Keyword(s):  
Silicon Film ◽  
Crystallization Rate ◽  
Ultra Violet ◽  
Hole Mobility ◽  
Metal Induced Crystallization ◽  
Polysilicon Films ◽  
Novel Method ◽  
Uv Photons ◽  
Lateral Crystallization ◽  
Induced Crystallization

ABSTRACTA novel method of UV-assisted metal-induced-crystallization is introduced to grow polysilicon films on ordinary glass at temperatures as low as 400°C. Annealing is accomplished in the presence of an ultra-violet exposure, leading to high crystallinity of the silicon film as confirmed by XRD, TEM and SEM analyses. A back-reflecting chromium layer is incorporated to further trap UV photons and enhance their absorption in the silicon film. This results in a significant increase in the crystallization rate as studied by XRD spectroscopy. A growth rate of 2 µm/hr is observed at 400 °C, when employing this method for lateral crystallization. Thin-film transistors fabricated using the proposed UV-assisted MILC show a threshold voltage of 1V and hole mobility of about 50 cm2/V.s.

A New Field-Aided Germanium-Induced Lateral Crystallization of Silicon

2001 ◽  
Vol 664 ◽  
Author(s):  
Kianoush Naeli ◽  
Shamsoddin Mohajerzadeh ◽  
Ali Khakifirooz ◽  
Saber Haji ◽  
Ebrahim A. Soleimani
Keyword(s):  
Electric Field ◽  
Grain Growth ◽  
Negative Electrode ◽  
Crystallization Rate ◽  
Lateral Growth ◽  
Annealing Temperatures ◽  
Lateral Crystallization ◽  
Si Films ◽  
First Time ◽  
Induced Crystallization

ABSTRACTThe effect of an electric field on germanium-seeded lateral crystallization of a-Si is studied for the first time and compared to this effect in Ni-induced lateral growth. While the crystallization rate is lower when Ge is used as the nucleation seed and annealing should be done at higher temperatures, filed-aided crystallization shows a similar behavior to that observed for Ni-induced crystallization. Optical microscopy results indicate that grain growth starting from the negative electrode occurs in Si films at annealing temperatures higher than 480°C, while the applied electric field ranges form 200 to 1400V/cm. SEM was also used to confirm the crystallinity of the films.

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