Waterborne epoxy-modified polyurethane-acrylate dispersions with nano-sized core-shell structure particles: synthesis, characterization, and their coating film properties

2017 ◽  
Vol 37 (2) ◽  
pp. 113-123 ◽  
Author(s):  
Jing Sun ◽  
Huagao Fang ◽  
Haili Wang ◽  
Shanzhong Yang ◽  
Shengrong Xiao ◽  
...  
Keyword(s):  
Shell Structure ◽  
Core Shell ◽  
Coating Film ◽  
Coating Films ◽  
Polyurethane Acrylate ◽  
Transmission Electron ◽  
Step Procedure ◽  
Waterborne Epoxy ◽  
Core Shell Structure ◽  
Thermo Stability

Abstract Waterborne epoxy-modified polyurethane-acrylate (EPUA) dispersions with nano-sized core-shell structure particles, with polyacrylate (PA) as core and epoxy-modified polyurethane (EPU) as shell, were successfully prepared via a two-step procedure. The waterborne EPU dispersions were first synthesized to serve as seeds, and then the butyl acrylate (BA) and methyl methacrylate (MMA) monomers were introduced into EPU particles to form polymeric core by radical polymerization under the assistance of ultrasonic treatment. Fourier transform infrared (FT-IR) spectroscopy revealed that the epoxy and PA components were successfully incorporated onto the chain of the PU and EPU to form EPU and EPUA, respectively. The transmission electron microscopy (TEM) photograph demonstrated that the EPUA particles have the core-shell structure. The as-prepared EPUA coating films exhibited good thermo-stability and mechanical properties, as revealed by thermogravimetric analysis (TGA) and tensile testing, respectively. The results of potentiodynamic polarization curves and immersion corrosion testing in 5 wt% NaCl aqueous solution both demonstrated that the anticorrosive properties of EPUA mainly depended on the mass content of PA, with the optimized value of 30 wt%.

Toughening Modification of PA6 with Different Core-Shell Particles

2013 ◽  
Vol 750-752 ◽  
pp. 820-823
Author(s):  
Zhen Yu Liu ◽  
Yu Zhu Xiong ◽  
Wen Jie Mei ◽  
Li Wang
Keyword(s):  
Electron Microscopy ◽  
Impact Strength ◽  
Shell Structure ◽  
Performance Test ◽  
Mechanical Performance ◽  
Core Shell ◽  
Transmission Electron ◽  
Notch Impact Strength ◽  
Core Shell Structure ◽  
Shell Particles

(POE-g-MAH/OMMT) and (POE-g-MAH/SiO2) toughening particles of core-shell structure were prepared by ball grinding method and were used to modify toughness of PA6.The morphology of PA6 modified by these core-shell particles were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM),and were detected by mechanical performance test. The results show that both toughening particles could improved notch impact strength of PA6,and with toughening particle exceed 10%, composites notch impact strength is rapid increase.(POE-g-MAH/OMMT) particle of PA6 toughening effect is better than (POE-g-MAH/SiO2).When material under impact, OMMT produced slip effect in core-shell structure and SiO2 produced rolling effect.

Microstructures and Highly Accelerated Lifetime Test of X5R Type BaTiO3-Based Ni-MLCC with Ultra-Thin Active Layers

2014 ◽  
Vol 602-603 ◽  
pp. 695-699
Author(s):  
Hui Ling Gong ◽  
Xiao Hui Wang ◽  
Shao Peng Zhang ◽  
Xin Ye Yang ◽  
Long Tu Li
Keyword(s):  
Dielectric Properties ◽  
Shell Structure ◽  
Casting Process ◽  
Thin Layers ◽  
Core Shell ◽  
Active Layers ◽  
Transmission Electron ◽  
Lifetime Test ◽  
Accelerated Lifetime ◽  
Core Shell Structure

Microstructure control in thin-layer multilayer ceramic capacitors (MLCCs) is one of the challenges for increasing capacitive volumetric efficiency and high voltage dielectric properties. In this paper, the X5R-MLCCs with ultra-thin dielectric layers (~1.2 μm) owning uniform grain size distribution were prepared by wet casting process. The microstructures and dielectric properties of the MLCCs were investigated. The existence of core-shell structure was proved by transmission electron microscopy observation and energy dispersive spectroscopy analysis. The existence of core-shell structure makes the temperature coefficient of capacitance (TCC) performance meet X5R standard. Moreover, a highly accelerated lifetime test (HALT) result shows that MLCCs with ultra-thin layers under high electric field are more easily to fail with increasing test temperatures. And the results reveal that the activation energy is similar to the value reported for mid-dielectric constant dielectrics.

A BIO-INSPIRED POLYDOPAMINE APPROACH TO PREPARATION OF GOLD-COATED Fe3O4 CORE–SHELL NANOPARTICLES: SYNTHESIS, CHARACTERIZATION AND MECHANISM

NANO ◽  
2013 ◽  
Vol 08 (06) ◽  
pp. 1350061 ◽  
Author(s):  
PENG AN ◽  
FANG ZUO ◽  
XINHUA LI ◽  
YUANPENG WU ◽  
JUNHUA ZHANG ◽  
...  
Keyword(s):  
Shell Structure ◽  
Room Temperature ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
Stabilizing Agent ◽  
X Ray ◽  
Transmission Electron ◽  
Core Shell Structure ◽  
Core Shell Nanoparticles

A biomimetic and facile approach for integrating Fe 3 O 4 and Au with polydopamine (PDA) was proposed to construct gold-coated Fe 3 O 4 nanoparticles ( Fe 3 O 4@ Au – PDA ) with a core–shell structure by coupling in situ reduction with a seed-mediated method in aqueous solution at room temperature. The morphology, structure and composition of the core–shell structured Fe 3 O 4@ Au – PDA nanoparticles were characterized by transmission electron microscopy (TEM), X-ray powder diffraction (XRD) and X-ray photoelectron spectrometry (XPS). The formation process of Au shell was assessed using a UV-Vis spectrophotometer. More importantly, according to investigating changes in PDA molecules by Fourier transform infrared spectroscopy (FTIR) and in preparation process of the zeta-potential data of nanoparticles, the mechanism of core–shell structure formation was proposed. Firstly, PDA-coated Fe 3 O 4 are obtained using dopamine (DA) self-polymerization to form thin and surface-adherent PDA films onto the surface of a Fe 3 O 4 "core". Then, Au seeds are attached on the surface of PDA-coated Fe 3 O 4 via electrostatic interaction in order to serve as nucleation centers catalyzing the reduction of Au 3+ to Au 0 by the catechol groups in PDA. Accompanied by the deposition of Au , PDA films transfer from the surface of Fe 3 O 4 to that of Au as stabilizing agent. In order to confirm the reasonableness of this mechanism, two verification experiments were conducted. The presence of PDA on the surface of Fe 3 O 4@ Au – PDA nanoparticles was confirmed by the finding that glycine or ethylenediamine could be grafted onto Fe 3 O 4@ Au – PDA nanoparticles through Schiff base reaction. In addition, Fe 3 O 4@ Au – DA nanoparticles, in which DA was substituted for PDA, were prepared using the same method as that for Fe 3 O 4@ Au – PDA nanoparticles and characterized by UV-Vis, TEM and FTIR. The results validated that DA possesses multiple functions of attaching Au seeds as well as acting as both reductant and stabilizing agent, the same functions as those of PDA.

Effect of protamine on Fe3O4@CS@GFTN composite magnetic nanoparticles

2019 ◽  
Vol 13 (02) ◽  
pp. 2050001 ◽  
Author(s):  
Huiping Shao ◽  
Luhui Wang ◽  
Tao Lin ◽  
Yumeng Zhang ◽  
Zhinan Zhang
Keyword(s):  
Magnetic Nanoparticles ◽  
Shell Structure ◽  
Lung Diseases ◽  
Core Shell ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Core Shell Structure ◽  
Average Size ◽  
Chemical Coprecipitation Method

Fe3O4@chitosan (CS)@Gefitinib (GFTN) core-shell structure composite magnetic nanoparticles (NPs) were prepared by chemical coprecipitation method in this study. In addition, protamine was doped in Fe3O4 cores to prepare Fe3O4@protamine@CS@GFTN core-shell structure composite NPs, in order to increase the loading of GFTN in composite NPs. They were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM) and spectrophotometer. The results show that the average size of Fe3O4@CS@GFTN and Fe3O4@protamine@CS@GFTN composite NPs is approximately 19 and 21[Formula: see text]nm, respectively. The saturation magnetizations of composite magnetic NPs and corresponding magnetic fluids are 57.20, 20.79, 59.58 and 19.75[Formula: see text]emu/g, respectively. The loading of GFTN in composite NPs was measured by a spectrophotometer to be about 13.5% and 27.6%, respectively. The addition of protamine increased the loading of GFTN two times, indicating that it will play an important role in the management of lung diseases.

Visualizing a core–shell structure of heavily doped silicon quantum dots by electron microscopy using an atomically thin support film

Nanoscale ◽  
2018 ◽  
Vol 10 (16) ◽  
pp. 7357-7362 ◽  
Author(s):  
Hiroshi Sugimoto ◽  
Masataka Yamamura ◽  
Makoto Sakiyama ◽  
Minoru Fujii
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Shell Structure ◽  
Core Shell ◽  
Oxide Support ◽  
Si Quantum Dot ◽  
Transmission Electron ◽  
Doped Silicon ◽  
Heavily Doped ◽  
Core Shell Structure

We successfully visualize a core–shell structure of a heavily B and P codoped Si quantum dot (QD) by transmission electron microscopy using an ultra-thin graphene oxide support film.

The Production of Core-Shell Structure Carboxylated Carbon Nanotubes/Polypyrrole Composite Materials in Different Reaction Media and Further Investigation on their Core-Shell Structure

2017 ◽  
Vol 730 ◽  
pp. 37-41 ◽  
Author(s):  
Hui Li Cao ◽  
Yuan Chang Shi ◽  
Hao Shen ◽  
Hu Dong Zhan ◽  
Jiu Rong Liu
Keyword(s):  
Carbon Nanotubes ◽  
Electron Microscope ◽  
Composite Materials ◽  
Shell Structure ◽  
Core Shell ◽  
Transmission Electron ◽  
Ft Ir ◽  
Core Shell Structure ◽  
Polypyrrole Composite ◽  
Carboxylated Carbon Nanotubes

In this paper carboxylated carbon nanotubes/polypyrrole composite (CNTs/PPy) was synthesized in different surfactants aqueous under sonication. Carboxylated CNTs was synthesized in hydrogen nitrate by ultrasonic method and coated by PPy. The synthesized CNTs/PPy in different surfactants was evaluated by Fourier transform infrared spectrometer (FT-IR) and transmission electron microscope. The FT-IR patterns illustrate that CNTs were successfully doped by PPy. The morphology of CNTs/PPy synthesized showed on the transmission electron microscope images. The composite materials sythesized without surfactant are easy reunited. It is also found the surface of CNTs/PPy synthesized in cetyl trimethyl ammonium bromide (CTAB) is smoother than that in other surfactants. The coating effect is better with thicker coating layer. The higher magnification of HRTEM images show the PPy was deposited directly on the surface of carbon nanotubes. The final products are the ordered coaxial composite with well-defined core-shell structure.

Preparation of Ultrafine Polyethylene-Silica Composite Particle with Core-Shell Structure

2012 ◽  
Vol 557-559 ◽  
pp. 554-557 ◽  
Author(s):  
Lei Zu ◽  
Shun Yu Han ◽  
Kai Gu ◽  
Xiu Guo Cui
Keyword(s):  
Shell Structure ◽  
Composite Particle ◽  
Sol Gel ◽  
Core Shell ◽  
Silica Composite ◽  
Transmission Electron ◽  
Mean Size ◽  
The Mean ◽  
Core Shell Structure ◽  
Electronic Microscope

A novel ultrafine polyethylene/silica composite particle with core-shell structure was prepared by the sol-gel method in the presence of the melt polyethylene emulsion. A series of samples with different polyethylene content were prepared to investigate the unique characteristics of this original composite particle. The core-shell structure and composition of the composite particle was proved by the transmission electron microscopy observation and Fourier transform infrared spectra. The composite particles possess a spherical morphology and the mean size is about 160nm, presented by the scanning electronic microscope observation and nanoparticle tracking analysis, respectively.

scholarly journals Microstructure of Surface and Subsurface Layers of a Ni-Ti Shape Memory Microwire

2009 ◽  
Vol 15 (1) ◽  
pp. 62-70 ◽  
Author(s):  
H. Tian ◽  
D. Schryvers ◽  
S. Shabalovskaya ◽  
J. Van Humbeeck
Keyword(s):  
Oxide Layer ◽  
Shell Structure ◽  
Core Shell ◽  
Strong Temperature Dependence ◽  
Transmission Electron ◽  
Subsurface Layers ◽  
Thick Oxide Layer ◽  
Core Shell Structure ◽  
Cold Worked ◽  
Microscopy Techniques

AbstractThe microstructure of a 55 μm diameter, cold-worked Ni-Ti microwire is investigated by different transmission electron microscopy techniques. The surface consists of a few hundred nanometer thick oxide layer composed of TiO and TiO2with a small fraction of inhomogeneously distributed Ni. The interior of the wire has a core-shell structure with primarily B2 grains in the 1 μm thick shell, and heavily twinned B19′ martensite in the core. This core-shell structure can be explained by a concentration gradient of the alloying elements resulting in a structure separation due to the strong temperature dependence of the martensitic start temperature. Moreover, in between the B2 part of the metallic core-shell and the oxide layer, a Ni3Ti interfacial layer is detected.

Study of Core-Shell Structure Poly(vinyl Acetate-Butyl Acrylate) Emulsion Particles Modification

2014 ◽  
Vol 1061-1062 ◽  
pp. 277-282 ◽  
Author(s):  
Gang Li ◽  
Ting Wang ◽  
Xin Fu ◽  
Tian Ming Gao ◽  
Mao Fang Huang
Keyword(s):  
Vinyl Acetate ◽  
Shell Structure ◽  
Butyl Acrylate ◽  
Core Shell ◽  
The Third ◽  
Transmission Electron ◽  
Acrylate Emulsion ◽  
Ft Ir ◽  
Emulsion Film ◽  
Core Shell Structure

Core-Shell structure Poly(vinyl acetate-butyl acrylate) emulsion is prepared by the semi-continuous emulsion polymerization. And the emulsion particles are modified by ethyleneglycol dimethacrylate crosslinker (EGDMA) to improve the properties of films in the different reaction stages. Then the emulsion particles structure is characterized by transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FT-IR). The particle size and distribution are characterized by Zata Potential- Particle analyzer, as well as analysis of the film mechanical properties and thermal performance. The results show that the emulsion particles possess a clear core-shell structure. The performance of the emulsion film show better when 1% and 0.5% EGDMA are added in the second reaction and the third reaction stage respectively under the emulsion preparation process.

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