scholarly journals Graphene/SiO2 nanocomposites: The enhancement of photocatalytic and biomedical activity of SiO2 nanoparticles by graphene

2017 ◽  
Vol 121 (24) ◽  
pp. 244901 ◽  
Author(s):  
Aqsa Arshad ◽  
Javed Iqbal ◽  
Qaisar Mansoor ◽  
Ishaq Ahmed
Keyword(s):  
Sio2 Nanoparticles ◽  
Sio2 Nanocomposites

The Dynamical Property and Abrasion Performance of Polyester Polyurethane/SiO2 Nanocomposite

2013 ◽  
Vol 668 ◽  
pp. 327-330
Author(s):  
Hao Shi ◽  
Yu Hua Li
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Tensile Strength ◽  
Dynamical Property ◽  
Sio2 Nanoparticles ◽  
Nano Sio2 ◽  
Sio2 Nanocomposites ◽  
Scanning Electron

Polyester based polyurethane/ SiO2 nanocomposites having the starting nNCO/nOH=2:1 and different concentrations of SiO2 nanoparticles (0, 0.2, 0.5, 1.0 and 2.0 wt %) have been prepared. The morphology, dynamical property and abrasion performance were analyzed using scanning electron microscopy, DMA and DIN abrasion tester separately. The results showed SiO2 uniformally dispersed in the composite. By adding nano SiO2 into the elastomers, the 300% modulus, tensile strength, die C tear of the composite were increased but the elongation and rebound decreased. With the increase of the SiO2 adding amount, tanδ of the composite increased gradually, the abrasion performance increased first and the declined.

Study Of Some Mechanical Properties For Epoxy/ SiO2 Nano Particles Reinforced With 6 Layers Of CM E-Glass Fibers Composites

2016 ◽  
pp. 3399-3407
Author(s):  
Ahmed Jadah Farhan ◽  
Ruaa Hilal
Keyword(s):  
Impact Strength ◽  
Volume Fraction ◽  
Glass Fibers ◽  
Sio2 Nanoparticles ◽  
Nano Particles ◽  
Molding Method ◽  
Nanoparticles Volume Fraction ◽  
Sio2 Nanocomposites ◽  
The Impact ◽  
Random Behaviour

In this study, the neat epoxy and nanocomposites with volume fraction (1, 3, 5, 7 and10%) of nano SiO2 particles reinforced with six layers of chopped mat E-glass fibers (CM) specimens were prepared by molding method. The results of Impact strengths of EP/SiO2 nanocomposites reinforced with 6 layers of CM E-glass fibers showed that Impact strength has a random behaviour with increasing volume fraction of SiO2 nanoparticles. The results showed an increase of Impact strengths with increasing the SiO2  nanoparticles volume fraction at 1% vol. of SiO2 nanoparticles, then decreases with increasing volume fraction at 3% vol. of SiO2 nanoparticles, then the Impact strength increases with increasing volume fraction of SiO2 nanoparticles until the Impact strength reach to maximum values  (78.93KJ/m2) at 7% vol. of SiO2 nanoparticles. And then Impact strength decreases with increasing volume fraction at 10% vol. of SiO2 nanoparticles.Also the results of shore D hardness of EP/SiO2 nanocomposites  reinforced with 6 layers of CM E-glass fibers showed that Hardness No. an increase with increasing the SiO2  nanoparticles volume fraction at 1% vol. of SiO2 nanoparticles, then decreases with increasing volume fraction at 3% vol. of SiO2 nanoparticles, then the Hardness No. increases with increasing volume fraction of SiO2 nanoparticles until the Hardness No. reach to maximum values  (85.03) at 10% vol. of SiO2 nanoparticles. 

Synthesis and Mechanical Properties of Advanced Polyimide/Silicon Dioxide Nanocomposites

2007 ◽  
Vol 561-565 ◽  
pp. 709-712 ◽  
Author(s):  
Qing Xin Zhang ◽  
Kimiyoshi Naito ◽  
Yutaka Kagawa
Keyword(s):  
Silicon Dioxide ◽  
Coupling Agent ◽  
Sol Gel ◽  
Sio2 Nanoparticles ◽  
X Ray Diffraction ◽  
Interatomic Distances ◽  
X Ray ◽  
Sol Gel Process ◽  
Ft Ir ◽  
Sio2 Nanocomposites

Hybrid inorganic-organic materials based on a polyimide (PI) and silicon dioxide (SiO2) were prepared previously only via sol-gel approach. However, sol-gel processes have some critical limitations. The primary drawback is that the resultant gel is extremely fragile and sol-gel process is complicated and costly. In this study, using SiO2 nanoparticles polyimide/SiO2 nanocomposites were synthesized from 4,4'-diaminodiphenyl ether (ODA) and 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA). A coupling agent, 3-glycidyloxyporpl trimethoxysilane (GTMOS), was used to functionalize the SiO2 nanoparticles which enhanced the compatibility between polyimide and SiO2 nanoparticles. The microstructures of polyimide/SiO2 nanocomposites were characterized by Fourier transform infrared spectroscopy (FT-IR) and wide angle X-ray diffraction (WAXD). All the polyimides show typical noncrystalline X-ray diffraction. The frequent occurrence of particular interatomic distances (R) denoted by the noncrystalline WAXD maxima were determined. All the modulus, strength and fracture strain of polyimide were improved with 5 wt% SiO2 modified with the coupling agent.

Multilayer Polymeric Nano composite Membrane for Oxygen Separation

2019 ◽  
Vol 1 (2) ◽  
pp. 1-11
Author(s):  
Gobi Nallathambi ◽  
Hazel Dhinakaran
Keyword(s):  
Polymer Concentration ◽  
Sio2 Nanoparticles ◽  
Air Separation ◽  
Regression Equations ◽  
Permeate Flux ◽  
Nano Composite ◽  
Box Behnken Design ◽  
Oxygen Selectivity ◽  
Multilayer Membrane ◽  
Spun Fiber

Air separation is a process of separating primary components from the atmospheric air. Development of membrane technologies plays a key role in air separation. Multi-layer polymeric nanocomposite membranes have been developed by a novel technique using Polyacrylonitrile (PAN) and cellulose acetate (CA) along with nano silica particles (SiO2) to obtain a higher oxygen selectivity and permeability. For the construction of the multilayer membrane, the Box-Behnken design has been used by employing three independent variables namely PAN Electro spinning time, the SiO2 percentage in the PAN polymer and CA/PEG polymer concentration. The developed membranes have been characterized for its surface morphology and physical properties. Along with the analysis of compound desirability, the results were also subject to statistical analysis in order to form regression equations. The electro spun fiber diameter increases along with the concentration of SiO2 nanoparticles and the range is from 50 nm to 400 nm. Moreover, the maximum pore size on the surface of the membrane lies between 200 to 400 nm whereas the maximum percentage of oxygen purity obtained is 48 with the permeate flux of 5.45 cm3/cm2/min.

4-Hydroxy Pyridinium Triflate@SiO2 Nanoparticles as a Novel Efficient Catalyst for Fries Rearrangement of Aryl Esters with High Selectivity

2020 ◽  
Vol 17 (8) ◽  
pp. 654-660
Author(s):  
Shermineh Sadat Ghalehbandi ◽  
Dadkhoda Ghazanfari ◽  
Sayed Ali Ahmadi ◽  
Enayatollah Sheikhhosseini
Keyword(s):  
High Selectivity ◽  
Sio2 Nanoparticles ◽  
High Yield ◽  
Synthetic Method ◽  
Functionalized Silica ◽  
Efficient Catalyst ◽  
Fries Rearrangement ◽  
Free Condition ◽  
Solvent Free Condition ◽  
Work Up

Introduction: We developed a simple, fast and new method for the Fries rearrangement of aryl esters. Materials and Methods: 4-Hydroxy pyridinium triflate functionalized silica is a very efficient, reusable and economically available catalyst for the Fries rearrangement in solvent-free condition and under microwave irradiation. Results and Discussion: Also, a notable selectivity was observed in the presence of 4-hydroxy pyridinium triflate functionalized silica. Conclusion: Selectivity, shorter reaction time, high yield, and easy work-up are advantages of this synthetic method.

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