scholarly journals Investigation of Dispersion, Interfacial Adhesion of Isotropic and Anisotropic Filler in Polymer Composite

2021 ◽  
Vol 11 (18) ◽  
pp. 8561
Author(s):  
Sneha Samal ◽  
Ignazio Blanco
Keyword(s):  
Polymer Matrix ◽  
Interfacial Adhesion ◽  
Simulation Method ◽  
Spherical Particles ◽  
Rubber Matrix ◽  
Anisotropic Particles ◽  
Uniform Size ◽  
Boundary Area ◽  
Surface Features ◽  
Contact Points

The movement of isotropic and anisotropic particles of iron and graphite within the polymer matrix was predicted and examined by the COMSOL simulation method. The interfacial adhesion of filler particles within the matrix was investigated under surface features observation. Carbonyl Iron (CI) particles, considered to be regular with a uniform size of (1–5 µm), were mixed with irregular particles of graphite (20–150 µm) with 30 V% in quantity in a silicone rubber matrix. The particle–matrix and particle–particle interactions were analyzed from the inner surface features. The drag of non-spherical particles and particle Reynolds numbers (Rep) were taken into consideration in point force models for both the Stokes (Rep ≪ 1) and Newton regime for particle shape. Newton regime is based on the aspect ratio for particles with regular and irregular shapes. The boundary area of the irregular particles holds like an anchor inside the polymer matrix for strong adhesion; however, regular particles have partial attachment due to the gravitational pull of attraction from the bottom contact points. However, uniform distribution of isotropic particles has been observed in comparison to the anisotropic particles within the polymer matrix.

Microstructure and Spectroscopy of Lu2O3:Eu Prepared Using Various Synthesis Techniques

2004 ◽  
Vol 99-100 ◽  
pp. 25-30 ◽  
Author(s):  
E. Zych ◽  
J. Trojan-Piegza ◽  
L. Kępiński ◽  
P. Dorenbos
Keyword(s):  
Uniform Distribution ◽  
Spherical Particles ◽  
Nanocrystalline Powders ◽  
Nanocrystalline Powder ◽  
Homogeneous Precipitation ◽  
Uniform Size ◽  
X Ray ◽  
Methods Of Synthesis ◽  
Excited Luminescence ◽  
Subsequent Decomposition

Nanocrystalline powders of Lu2O3:Eu with activator content varying between 0.2%-10% were prepared using four different methods of synthesis. The products differed in their microstructure and crystallites sizes. Combustion of Lu(NO3)3 with urea produced strongly agglomerated material, most probably with significantly non-uniform distribution of the Eu3+ dopant. Replacing urea with glycine for the combustion produced only slightly agglomerated, voluminous, fluffy powder. Applying the Pechini technique resulted in significantly agglomerated powder while the homogeneous precipitation of Lu(OH)3 with urea at 90 °C and its subsequent decomposition to Lu2O3 at 650 °C resulted in a powder of perfectly spherical particles with a uniform size of about 130 nm with very low agglomeration. The efficiency of X-ray excited luminescence of our nanocrystalline Lu2O3:5%Eu was compared to that of the commercial microcrystalline Gd2O2S:Eu. It was found that the commercial phosphor performed four times more efficiently than our nanocrystalline powder. We consider this to be rather encouraging as the fabrication of our powder is not optimized yet. It seems that Lu2O3:Eu, even in nanocrystalline form, can perform much more efficiently which would make it a promising X-ray phosphor.

scholarly journals Pressureless and Low-Pressure Synthesis of Microporous Carbon Spheres Applied to CO2 Adsorption

Molecules ◽  
2020 ◽  
Vol 25 (22) ◽  
pp. 5328
Author(s):  
Iwona Pełech ◽  
Daniel Sibera ◽  
Piotr Staciwa ◽  
Urszula Narkiewicz ◽  
Robert Cormia
Keyword(s):  
Co2 Adsorption ◽  
Applied Pressure ◽  
Low Pressure ◽  
Spherical Particles ◽  
Co2 Uptake ◽  
Pressure Treatment ◽  
Carbon Spheres ◽  
Potassium Oxalate ◽  
Uniform Size ◽  
Pressure Synthesis

In this work, low-pressure synthesis of carbon spheres from resorcinol and formaldehyde using an autoclave is presented. The influence of reaction time and process temperature as well as the effect of potassium oxalate, an activator, on the morphology and CO2 adsorption properties was studied. The properties of materials produced at pressureless (atmospheric) conditions were compared with those synthesized under higher pressures. The results of this work show that enhanced pressure treatment is not necessary to produce high-quality carbon spheres, and the morphology and porosity of the spheres produced without an activation step at pressureless conditions are not significantly different from those obtained at higher pressures. In addition, CO2 uptake was not affected by elevated pressure synthesis. It was also demonstrated that addition of the activator (potassium oxalate) had much more effect on key properties than the applied pressure treatment. The use of potassium oxalate as an activator caused non-uniform size distribution of spherical particles. Simultaneously higher values of surface area and total pore volumes were reached. A pressure treatment of the carbon materials in the autoclave significantly enhanced the CO2 uptake at 25 °C, but had no effect on it at 0 °C.

INTERFERENCE EFFECTS IN THE SMALL ANGLE SCATTERING OF X RAYS BY SMALL PARTICLES

1953 ◽  
Vol 31 (1) ◽  
pp. 40-48 ◽  
Author(s):  
G. E. Noakes ◽  
Elizabeth J. Allin
Keyword(s):  
Small Angle ◽  
Particle Distribution ◽  
Spherical Particles ◽  
Unique Determination ◽  
X Rays ◽  
Interference Effects ◽  
Uniform Size ◽  
Gold Colloids ◽  
Interference Maximum ◽  
Angle Scattering

Interparticle interference effects have been observed in the small angle X-ray-scattering from 30 samples prepared by the evaporation of gold colloids containing spherical particles of uniform size. The position of the interference maximum was found not to be the same for all samples containing particles of the same size. Calculation verifies that the position of this maximum is dependent on the radial distribution of the particles. It cannot be used for size determinations unless this distribution is known. The predicted variation of the slope at small angles of the In I vs. k2 curve with particle distribution was confirmed experimentally. This method of size determination is unsatisfactory whenever interference effects are present. It is suggested that size determinations based on the positions of the form function maxima are almost independent of particle distribution even in concentrated samples. A unique determination of the particle distribution from the position and shape of the interference maximum would appear to be impossible even if the size were known.

scholarly journals Study of Interfacial Adhesion between Nickel-Titanium Shape Memory Alloy and a Polymer Matrix by Laser Surface Pattern

2020 ◽  
Vol 10 (6) ◽  
pp. 2172 ◽  
Author(s):  
Sneha Samal ◽  
Ondřej Tyc ◽  
Luděk Heller ◽  
Petr Šittner ◽  
Monika Malik ◽  
...  
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Mechanical Testing ◽  
Polymer Matrix ◽  
Interfacial Adhesion ◽  
Laser Surface ◽  
Surface Pattern ◽  
Multiple Cracks ◽  
Laser Machine ◽  
Pmma Matrix

The aim of this article is to investigate the interfacial adhesion of Ni-Ti shape memory alloy with a polymer matrix of Poly (methyl methacrylate) (PMMA). The surface pattern on Ni-Ti plates was channeled by a solid state laser machine. The laser machine allows for creating channels on the Ni-Ti surface for infiltration of the PMMA matrix, which could be attached as an intra-surface locking pattern to the Ni-Ti surface. The influence of the PMMA matrix on the surface of the NiTi plate was evaluated by thermomechanical analysis (TMA) and dynamic mechanical analysis (DMA). The surface characterization was carried out by an optical microscope on the PMMA/NiTi composite after mechanical testing. During mechanical testing, the polymer displays the multiple cracks in the longitudinal direction that result in slipping and fracture. TMA and DMA analyses were performed on the Ni-Ti- and PMMA-coated Ni-Ti ribbon to observe elasticity and the storage modulus for both samples. Better adhesion than 80 % was observed in the Ni-Ti surface, in the laser surface pattern, in comparison to the free plain surface. However, the polymer acts as mechanical backing that caused a reduction in the shape-memory properties of the composite material.

Buckling of Graphene Embedded in Polymer Matrix Under Compression

2015 ◽  
Vol 15 (07) ◽  
pp. 1540016 ◽  
Author(s):  
F. Lin ◽  
Y. Xiang ◽  
H.-S. Shen
Keyword(s):  
Polymer Matrix ◽  
Md Simulations ◽  
Simulation Method ◽  
Monolayer Graphene ◽  
Graphene Sheets ◽  
Mechanical Behaviors ◽  
Free Standing ◽  
Aspect Ratios ◽  
Stress States ◽  
Critical Buckling Strain

Understanding the mechanical behaviors of graphene under different stress states is crucial to their applications. Comparing with the bucking behavior of free standing graphene under compression, the monolayer graphene embedded in the polymer matrix has a higher critical buckling load and smaller atomic length scale wavelengths as well as buckling amplitudes. In this paper, the molecular dynamics (MD) method is adopted to study the buckling behaviors of embedded graphene under uniaxial compression. Two MD models are built, namely the hybrid MD/continuum nanomechanics model and the full MD model. Periodical boundary conditions are applied in the MD simulations. Graphene sheets with different aspect ratios are considered and it is observed that the critical buckling strain of graphene sheets embedded in polymer matrix is independent of their aspect ratios. The current simulation results match well with the reported experimental results. Furthermore, it is demonstrated that the current simulation method can produce clear buckling shapes, which are difficult to observe in nanoscale experiments.

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