scholarly journals Dispersion and deagglomerat1on of nano-SiO2 particles with a silane modification reagent in supercritical CO2

2007 ◽  
Vol 61 (3) ◽  
pp. 109-116
Author(s):  
Dusica Stojanovic ◽  
Goran Vukovic ◽  
Aleksandar Orlovic ◽  
Petar Uskokovic ◽  
Radoslav Aleksic ◽  
...  
Keyword(s):  
Conventional Method ◽  
Supercritical Co2 ◽  
Particle Surface ◽  
Comparison Method ◽  
The Other ◽  
Hydroxyl Groups ◽  
Nano Sio2 ◽  
Coupling Reagent ◽  
Silane Coupling ◽  
Sio2 Particles

The supercritical CO2 method was used in order to perform deagglomeration and improve the dispersion of nano-SiO2 particles. ?-Met-hacryloxypropyltrimethoxysilane was used as the surface modification reagent. The conventional method for coating nano-SiO2 particles was used as the comparison method. Considerable improvement of the dispersion and deagglomeration was found using supercritical CO2. Analysis of the TEM micrographs and DLS results showed the reduction of the average size of the agglomerates with the silane coupling reagent. Thermogravimetric analysis (TGA) showed that the particles treated in super?critical CO2 were more thermally stable than particles treated by conventional method. Encapsulation of several particles coated with the silane coupling reagent was observed in certain parts of the primary particles. A chemical reaction takes place between the modification reagent, MEMO silane, and active hydroxyl groups on the surface of the nano-SiO2 particles. A larger quantity of MEMO silane reacted using the con?ventional method instead of the supercritical method. On the other hand, the reacted silane molecules were better arranged around the particle surface in the supercritical method because of the formation of covalent or self-assembled structures. Polycondensed structures were preferentially obtained in the conventional method. This was achieved by using supercritical CO2, which has a high solvating power such as organic solvents and physical properties (low viscosity, low surface tension and high diffusion coefficient) similar to gases on the other side. These properties enable the sufficient and uniform wettability of nano-SiO2 particle surfaces. These results are important for obtaining nanofillers with improved dispersion and polymer wettability. Such nanofillers can be used to obtain composite materials with considerably improved mechanical characteristics.

scholarly journals Effects of Modified Nano-SiO2 Particles on Properties of High-Performance Cement-Based Composites

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 646 ◽  
Author(s):  
Zhidan Rong ◽  
Mingyu Zhao ◽  
Yali Wang
Keyword(s):  
Mechanical Properties ◽  
Coupling Agent ◽  
High Performance ◽  
Silane Coupling Agent ◽  
Nano Sio2 ◽  
Nucleation Effect ◽  
Silane Coupling ◽  
Static Mechanical ◽  
Sio2 Particles ◽  
Static Mechanical Properties

In this research, silane coupling agent was used to modify the surface of nano-SiO2, particles and the effects of modified nano-SiO2 particles on the mechanical properties of high-performance cement-based composites and its mechanism were systematically studied. The results indicated that the optimum modification parameters were a coupling agent content of 10%, reaction temperature of 65 °C, and reaction time of 8 h. Compared with the unmodified nano-SiO2, the modified nano-SiO2 promoted and accelerated the hydration process of cement. The pozzolanic effect, filling effect, and nucleation effect of modified nano-SiO2 made the microstructure of the composite more compact, and thus improved static mechanical properties of cement-based composites.

Organic modification of nano-SiO2 particles in supercritical CO2

2006 ◽  
Vol 37 (1) ◽  
pp. 125-130 ◽  
Author(s):  
Zhi-Wen Wang ◽  
Ting-Jie Wang ◽  
Zhan-Wen Wang ◽  
Yong Jin
Keyword(s):  
Supercritical Co2 ◽  
Organic Modification ◽  
Nano Sio2 ◽  
Sio2 Particles

scholarly journals Improved Hydrophobicity of Macroalgae Biopolymer Film Incorporated with Kenaf Derived CNF Using Silane Coupling Agent

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2254
Author(s):  
Adeleke A. Oyekanmi ◽  
N. I. Saharudin ◽  
Che Mohamad Hazwan ◽  
Abdul Khalil H. P. S. ◽  
Niyi G. Olaiya ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Coupling Agent ◽  
Silane Coupling Agent ◽  
Cellulose Nanofibrils ◽  
Hydroxyl Groups ◽  
Water Contact ◽  
Silane Coupling ◽  
Cnf Films ◽  
Kenaf Bast ◽  
Thermal Stability Of

Hydrophilic behaviour of carrageenan macroalgae biopolymer, due to hydroxyl groups, has limited its applications, especially for packaging. In this study, macroalgae were reinforced with cellulose nanofibrils (CNFs) isolated from kenaf bast fibres. The macroalgae CNF film was after that treated with silane for hydrophobicity enhancement. The wettability and functional properties of unmodified macroalgae CNF films were compared with silane-modified macroalgae CNF films. Characterisation of the unmodified and modified biopolymers films was investigated. The atomic force microscope (AFM), SEM morphology, tensile properties, water contact angle, and thermal behaviour of the biofilms showed that the incorporation of Kenaf bast CNF remarkably increased the strength, moisture resistance, and thermal stability of the macroalgae biopolymer films. Moreover, the films’ modification using a silane coupling agent further enhanced the strength and thermal stability of the films apart from improved water-resistance of the biopolymer films compared to unmodified films. The morphology and AFM showed good interfacial interaction of the components of the biopolymer films. The modified biopolymer films exhibited significantly improved hydrophobic properties compared to the unmodified films due to the enhanced dispersion resulting from the silane treatment. The improved biopolymer films can potentially be utilised as packaging materials.

scholarly journals Improvement of Rice Husk/HDPE Bio-Composites Interfacial Properties by Silane Coupling Agent and Compatibilizer Complementary Modification

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 1928 ◽  
Author(s):  
Jingmeng Sun ◽  
Yao Pang ◽  
Yingni Yang ◽  
Junqi Zhao ◽  
Rongqi Xia ◽  
...  
Keyword(s):  
Flexural Strength ◽  
Rice Husk ◽  
Coupling Agent ◽  
Silane Coupling Agent ◽  
Hydroxyl Groups ◽  
Compound System ◽  
High Polymer ◽  
Silane Coupling ◽  
Polymer Compound ◽  
Forestry Residues

Composites using agricultural and forestry residues as raw materials with potentially high-performance, multifunctional and biodegradable ecological advantages, are viewed as very promising for new-generation lightweight and low-cost bio-based sustainable building materials. At present, the research on wood-plastic composite materials is relatively mature. However, it is still a challenge to effectively use other biomass and improve the interface of the high-polymer compound system. Herein, we proposed a simple and effective method to enhance the interfacial adhesion properties of rice husk fibre and High Density Polyethylene (HDPE) composites by the silane coupling agent KH-550 and compatibilizer Maleic anhydride grafted polyethylene (MAPE) with complementary modification. It was found that the coupling agent KH-550 cross-linked with the hydroxyl group on the husk fibre surface and solidified with the high polymer by –NH–, –C=O– functional group generation. Compatibilizer MAPE strengthened the two phases by covalently bonding with an ester linkage and lowered the roughness of the cross-section of the composites. Meanwhile the modification enhanced the dispersibility, and mechanical properties of the husk-high polymer compound system, the bending and flexural strength were improved by 11.5% and 28.9% with KH-550, and MAPE added, respectively. The flexural strength of the composites increased by 40.7% after complementary modification. Furthermore, the complementary modification treatment reduced the hydrophilic hydroxyl groups and increased the molecular chain to improve the water-resistance, elastic modulus and toughness of the composite. This study prepared a bio-composite, which is expected to expand the use of agricultural and forestry residues as an extension of wood-plastic composites.

scholarly journals Improved ORB Algorithm Using Three-Patch Method and Local Gray Difference

Sensors ◽  
2020 ◽  
Vol 20 (4) ◽  
pp. 975
Author(s):  
Chaoqun Ma ◽  
Xiaoguang Hu ◽  
Jin Xiao ◽  
Huanchao Du ◽  
Guofeng Zhang
Keyword(s):  
Feature Fusion ◽  
Comparison Method ◽  
The Other ◽  
Binary String ◽  
Fusion Method ◽  
Feature Description ◽  
Binary Description ◽  
New Feature ◽  
Patch Group ◽  
Binary Strings

This paper presents an improved Oriented Features from Accelerated Segment Test (FAST) and Rotated BRIEF (ORB) algorithm named ORB using three-patch and local gray difference (ORB-TPLGD). ORB takes a breakthrough in real-time aspect. However, subtle changes of the image may greatly affect its final binary description. In this paper, the feature description generation is focused. On one hand, instead of pixel patch pairs comparison method used in present ORB algorithm, a three-pixel patch group comparison method is adopted to generate the binary string. In each group, the gray value of the main patch is compared with that of the other two companion patches to determine the corresponding bit of the binary description. On the other hand, the present ORB algorithm simply uses the gray size comparison between pixel patch pairs, while ignoring the information of the gray difference value. In this paper, another binary string based on the gray difference information mentioned above is generated. Finally, the feature fusion method is adopted to combine the binary strings generated in the above two steps to generate a new feature description. Experiment results indicate that our improved ORB algorithm can achieve greater performance than ORB and some other related algorithms.

Largely improved toughness of PP/EPDM blends by adding nano-SiO2 particles

Polymer ◽  
2007 ◽  
Vol 48 (3) ◽  
pp. 860-869 ◽  
Author(s):  
Hong Yang ◽  
Xiaoqing Zhang ◽  
Cheng Qu ◽  
Bo Li ◽  
Lijuan Zhang ◽  
...  
Keyword(s):  
Nano Sio2 ◽  
Sio2 Particles

Eight compact analysis systems evaluated for measuring total cholesterol

1994 ◽  
Vol 40 (4) ◽  
pp. 579-585 ◽  
Author(s):  
L C Gregory ◽  
S H Duh ◽  
R H Christenson
Keyword(s):  
Total Cholesterol ◽  
Total Error ◽  
Comparison Method ◽  
The Other ◽  
Sample Type ◽  
Average Bias ◽  
Error Limit ◽  
Absolute Bias ◽  
Allowable Error ◽  
The Mean

Abstract We examined the analytical performance of eight compact systems for measuring total cholesterol: AccuMeter, Cobas Ready, Discovery f2, DT60, L-D-X, Reflotron, QCA, and Vision. We determined average bias at two decision levels, the mean absolute bias, and the percentage of results differing from the comparison method results by > 8.9% allowable total error limit for multiple reagent lots. Average bias was < 3% for all lots tested for AccuMeter, Discovery f2, and DT60, but > 3% for one or more lots or sample types tested with the other systems. Of results from each reagent lot, > 95% were within the 8.9% total error specifications with Discovery f2, DT60, and QCA, whereas the performance of L-D-X, Vision, and Reflotron depended on reagent lot and (or) sample type. Of all results from each lot tested with AccuMeter and Cobas Ready, > 5% exceeded the total allowable error limit. We determined imprecision for five systems: Cobas Ready, Discovery f2, and QCA had CVs < 3%, whereas CVs for AccuMeter and L-D-X were > 3% but < 5%.

Sign in / Sign up

Export Citation Format

Share Document