scholarly journals Polypropylene Nanocomposites Obtained byIn SituPolymerization Using Metallocene Catalyst: Influence of the Nanoparticles on the Final Polymer Morphology

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Paula Zapata ◽  
Raúl Quijada
Keyword(s):  
Catalytic System ◽  
Sol Gel ◽  
Metallocene Catalyst ◽  
Particle Morphology ◽  
Polymer Particle ◽  
Silica Nanospheres ◽  
Sem Images ◽  
Transmission Electron ◽  
Polypropylene Nanocomposites

Polypropylene nanocomposites containing silica nanospheres based on the sol-gel methods were produced viain situpolymerization using a rac-Et(Ind)2ZrCl2/methylaluminoxane (MAO) system. Two different routes were used depending on the interaction between the silica nanoparticles with the catalytic system. In route 1 the nanoparticles were added together with the catalytic system (rac-Et(Ind)2ZrCl2)/(MAO) directly into the reactor, and in route 2 the metallocene rac-Et(Ind)2ZrCl2was supported on silica nanospheres pretreated with (MAO). SEM images show that when the nanospheres were added by both routes, they were replicated in the final polymer particle morphology; this phenomenon was more pronounced for PP obtained by route 2. The polypropylene (PP) nanocomposites obtained by both routes had a slightly higher percent crystallinities and crystallinity temperatures than pure PP. Transmission electron microscopy (TEM) images show that the nanospheres were well dispersed into the polypropylene matrix, particularly in the nanocomposites obtained by the support system (route 2).

Synthesis, Characterization and Properties of PANI/(La-Nd Doped BaFe12O19) Composites

2017 ◽  
Vol 727 ◽  
pp. 327-334
Author(s):  
Yan Wang ◽  
Jun Wang ◽  
Xiao Fei Zhang ◽  
Ya Qing Liu
Keyword(s):  
Sol Gel ◽  
Network Analyzer ◽  
X Ray Diffraction ◽  
Sem Images ◽  
Structure Morphology ◽  
Xrd Patterns ◽  
Hexagonal Platelet ◽  
Peak Value ◽  
Properties Of Composites

La-Nd co-doped barium hexaferrites, Ba0.7(LamNdn)0.3Fe12O19 (D-BaM), were successfully prepared by sol-gel method. PANI / D-BaM composites were synthesized by in-situ polymerization in solution. The structure, morphology and properties of samples have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), four-probe conductivity tester and vector network analyzer. The XRD patterns showed that the crystal structure of all the samples exist as M-type phases. The SEM images revealed that the particles presented a hexagonal platelet-like morphology. The magnetic properties could be improved by substitutions of La and Nd ions. The saturation magnetization (Ms) and coercive force (Hc) increased with the change of La / Nd ratio to the maximum at La / Nd = 3:1. The doped particles have also been embedded in conductive PANI to prepare electromagnetic materials, and the conductivity kept on the order of 10-2. The microwave absorbing properties of composites at 30 MHz-6 GHz improved obviously, the peak value of reflection loss could reach-7.5 dB.

Eu3+/Tb3+ Co-Doped Cerium Oxide Transparent Nanocomposite for Color-Tunable Emission

NANO ◽  
2018 ◽  
Vol 13 (10) ◽  
pp. 1850119
Author(s):  
Xiaoyan Li ◽  
Yunlong Yu ◽  
Xiangfeng Guan ◽  
Peihui Luo ◽  
Linqin Jiang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Thermal Stability ◽  
Transmission Electron Microscopy ◽  
Sol Gel ◽  
Homogeneous Precipitation ◽  
Transmission Electron ◽  
Color Tunable ◽  
Co Doped ◽  
Tunable Emission

Eu[Formula: see text]/Tb[Formula: see text] co-doped nanocomposite containing CeO2 nanocrystals was successfully prepared by an in situ sol–gel polymerization approach. High-resolution transmission electron microscopy demonstrated the homogeneous precipitation of CeO2 nanocrystals among the polymethylmethacrylate (PMMA) matrix. The thermal stability and UV-shielding capability of the obtained nanocomposite were improved with increase of CeO2 content. The tuning of the emissive color from green and yellow to red can be easily achieved by varying the dopant species and concentration. These results suggested that the obtained nanocomposite could be potentially applicable in transparent solid-state luminescent devices.

Preparation, characterization, and properties of polystyrene/Na-montmorillonite composites

2018 ◽  
Vol 32 (8) ◽  
pp. 1078-1091 ◽  
Author(s):  
Sibel Erol Dağ ◽  
Pınar Acar Bozkurt ◽  
Fatma Eroğlu ◽  
Meltem Çelik
Keyword(s):  
Electron Microscopy ◽  
Interlayer Spacing ◽  
Decomposition Temperature ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Sem Images ◽  
Specific Pore Volume ◽  
Transmission Electron ◽  
Thermal Stability Of

A series of polystyrene (PS)/unmodified Na-montmorillonite (Na-MMT) composites were prepared via in situ radical polymerization. The prepared composites were characterized using various techniques. The presence of various functional groups in the unmodified Na-MMT and PS/unmodified Na-MMT composite was confirmed by Fourier transform infrared spectroscopy. Morphology and particle size of prepared composites was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). According to the XRD and TEM results, the interlayer spacing of MMT layers was expanded. SEM images showed a spongy and porous-shaped morphology of composites. TEM revealed the Na-MMT intercalated in PS matrix. The thermal stability of PS/unmodified Na-MMT composites was significantly improved as compared to PS, which is confirmed using thermogravimetric analysis (TGA). The TGA curves indicated that the decomposition temperature of composites is higher at 24–51°C depending on the composition of the mixture than that of pure PS. The differential scanning calorimetry (DSC) results showed that the glass transition temperature of composites was higher as compared to PS. The moisture retention, water uptake, Brunauer–Emmett–Teller specific surface area, and specific pore volume of composites were also investigated. Water resistance of the composites can be greatly improved.

Silica and Silane Coupling Agent for in Situ Reinforcement of Acrylonitrile-Butadiene Rubber

1999 ◽  
Vol 72 (1) ◽  
pp. 119-129 ◽  
Author(s):  
K. Murakami ◽  
S. Osanai ◽  
M. Shigekuni ◽  
S. Iio ◽  
H. Tanahashi ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Sol Gel ◽  
Silica Particles ◽  
Butadiene Rubber ◽  
Acrylonitrile Butadiene Rubber ◽  
In Situ Silica ◽  
Transmission Electron ◽  
Dispersion Agent ◽  
The Relationship

Abstract In situ silica reinforcement for the acrylonitrile-butadiene rubber (NBR) vulcanizates, which were premixed with a conventional silica (VN-3) and γ-mercaptopropyltrimethoxysilane (γ-MPS), was achieved by the sol-gel reaction of tetraethoxysilane (TEOS) using ethylenediamine. It was observed that the reinforcement efficiency tended to increase with the increase of mechanically premixed conventional silica. From the observations of transmission electron microscopy and scanning electron microscopy, the simultaneous use of VN-3 and γ-MPS was found to promote the formation of large silica particles and clusters with a relatively good dispersion by the sol-gel reaction of TEOS in the NBR vulcanizate. The results of hysteresis measurements supported this promotion. It was considered to be due to the surface modification of VN-3 by the sol-gel reaction of TEOS and the presence of γ-MPS which worked as a dispersion agent for silica particles. The relationship between the mechanical properties and the morphology of the in situ silica filled vulcanizates is discussed.

Synthesis of Surface-Modified Oil-Soluble Silica Nanospheres and Investigation of their Tribological Behavior

2011 ◽  
Vol 266 ◽  
pp. 30-33 ◽  
Author(s):  
Xiao Hong Li ◽  
Jing Jing Huang ◽  
Tian Cong Cai ◽  
Zhi Jun Zhang
Keyword(s):  
Electron Microscope ◽  
Tribological Behavior ◽  
Engine Oil ◽  
Silica Nanospheres ◽  
Covalent Bonds ◽  
Transmission Electron ◽  
Soluble Silica ◽  
Promising Application ◽  
Surface Modified

Silica nanospheres with good dispersibility in oily solvents were prepared using a facile in-situ surface-modification route. The microstructure of resultant surface-capped silica nanospheres was analyzed with a transmission electron microscope. The tribological behavior of the silica nanospheres as additive in engine oil SE 15W/40 was evaluated using a four-ball machine; and the morphology and composition of the worn steel surfaces were analyzed using a scanning electron microscope equipped with an energy dispersive X-ray analysis attachment. It was found that organic modifier hexamethyldisilazane (HMDS) was combined with nano-SiO2 by covalent bonds, resulting in varied surface properties and improved dispersibility of the nanoparticles in many organic mediums. Besides, oil-soluble silica nanospheres as additive in the engine oil had excellent friction-reducing and antiwear abilities, showing promising application prospect.

In situ TEM crystallization of sol-gel derived BaTiO3 thin films

1994 ◽  
Vol 52 ◽  
pp. 588-589
Author(s):  
Martha L. Mecartney ◽  
M. C. Gust ◽  
N. D. Evans
Keyword(s):  
Thin Films ◽  
Sol Gel ◽  
In Situ Tem ◽  
Lattice Match ◽  
Gel Layer ◽  
Transmission Electron ◽  
Sol Gel Process ◽  
Good Lattice ◽  
Thick Layers

BaTiO3 thin films made by the sol-gel process require a crystallization heat treatment to transform the amorphous gel into a crystalline material. This work used a Ba-Ti methoxypropoxide precursor in a 0.25M solution of methoxypropanol which was spin coated as 5 (each -600 nm thick) layers on (100) Si (FIG. 1). The {100} planes of perovskite BaTiO3 have a good lattice match with {110} Si; d110 of Si = 0.38 nm, and d100 of BaTiO3 = 0.4 nm. Consequently, it should be possible to grow heteroepitaxial films of (100) BaTiO3 on (100) Si. Such samples pyrolized at 350.C and then annealed in a conventional furnace at 750°C for one hour, however, did not crystallize heteroepitaxially with the substrate. Rather, crystallization occurred by a nucleation and growth process from within the gel. Furthermore, the gel layer at the Si/BaTiO3 interface remained amorphous. In-situ hot stage experiments were conducted in a transmission electron microscope (TEM) to determine the nucleation and crystallization behavior.

Matrix-Assisted Formation of Metal Nanoparticles in Organosilica Sol-Gels

2002 ◽  
Vol 726 ◽  
Author(s):  
Sandie H. Cheung ◽  
Bakul C. Dave
Keyword(s):  
Metal Nanoparticles ◽  
Chemical Reduction ◽  
Sol Gel ◽  
Synthesis Method ◽  
Porous Silica ◽  
Ambient Conditions ◽  
Transmission Electron ◽  
Organically Modified ◽  
Structural Template

AbstractThe use of organosilica sol-gels for controlled in-situ formation of metal nanoparticles is investigated. The use of an organically-modified alkoxysilane precursor provides chemically interacting nanopores for the sequestration and binding of metal ions followed by chemical reduction to form metal nanoparticles. The sol-gel matrix acts as a structural template to enable growth of the metal nanoparticles within its porous silica framework, and prevents clustering to form precipitate. Furthermore, simple redox chemistry is used to convert pre-formed copper nanoparticles in the sol-gel matrix into silver and gold nanoparticles. A particularly important aspect of this synthesis method is that all the reaction chemistry is performed under ambient conditions. The particles are characterized by high resolution transmission electron microscopy for their sizes and size distribution. The elemental composition of the particles is determined by energy dispersive X-ray analysis.

The Effect of Bis(3-Triethoxysilylpropyl) Tetrasulfide on Silica Reinforcement of Styrene-Butadiene Rubber

1998 ◽  
Vol 71 (2) ◽  
pp. 289-299 ◽  
Author(s):  
A. S. Hashim ◽  
B. Azahari ◽  
Y. Ikeda ◽  
S. Kohjiya
Keyword(s):  
Fine Particles ◽  
Sol Gel ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Mechanical Mixing ◽  
Transmission Electron ◽  
Curing Characteristics ◽  
Sol Gel Process ◽  
Styrene Butadiene

Abstract Bis(3-triethoxysilylpropyl)tetrasulfide (TESPT) was found to affect the curing characteristics and the physical properties of styrene-butadiene (SBR) gum rubber and xin situ silica-filled SBR vulcanizates. Silica incorporated by the in situ sol-gel reaction of tetraethoxysilane with TESPT showed a much higher reinforcing efficiency than did conventional mechanical mixing and the in situ method without TESPT. The higher reinforcing efficiency is attributed to the formation of a silica-rubber network, which also changed the dynamic mechanical behavior of the SBR vulcanizates. Transmission electron microscopy observations showed in situ silica incorporation of very fine particles in comparison to the sol-gel process without TESPT.

Study on the Fabrication of Superhydrophobic Microporous Polypropylene Flat Membrane Using In Situ Synthesis of Modified Fluorinated Silica Nano Particles

2013 ◽  
Vol 829 ◽  
pp. 371-375 ◽  
Author(s):  
Saba Raveshiyan ◽  
Reza Yegani ◽  
Behzad Pourabbas ◽  
Akram Tavakkoli
Keyword(s):  
Pure Water ◽  
Sol Gel ◽  
Nano Particles ◽  
Sem Images ◽  
Cross Sectional ◽  
Transfer Resistance ◽  
Thermally Induced ◽  
Coated Membranes ◽  
Membrane Contactors

The wettability is the most important features of membrane, when it works as contactors. Although the membrane contactors offer many advantages over conventional contacting equipments, additional mass transfer resistance is introduced when micropores are filled with aqueous absorbents. Therefore, fabrication of superhydrophobic membrane which prevents diffusion of aqueous absorbent into membrane pores is a highly challenging task. In this work, superhydrophobic polypropylene (PP) membrane was fabricated using in situ synthesis of silica nano particles via thermally induced phase separation (TIPS) method. Flat sheet fabricated PP membranes were casted with methanolic solution containing various ratios of perfluorooctyltriethoxysilane (PFOTES)/ tetraethylortosilicate (TEOS) and then sol-gel reaction between the mixed silances was completed. The contact angle of coated membrane was reached to 168 degree, when the percentage of PFOTES/TEOS was fixed at 50% (mol/mol). Interestingly, due to the microporous structure of PP membrane, the synthesized fluorinated silica nanoparticles were observed on the surface as well as in the cross-sectional area of the membrane. Field emission scanning electron microscopy (FE-SEM) images were confirmed this point. Chemical structure of the coated membranes with 50% PFOTES was compared with pure PP membrane using ATR-IR. In order to evaluate the operational performance, coated membranes were immersed in aqueous solutions of mono ethanol amine (MEA), di ethanol amine (DEA) and pure water. In comparison with pure PP membrane, obtained results showed that the wettability of coated membranes was considerably decreased.

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