scholarly journals The The research to improve the mechanical properties and the water barrier properties of polyvinyl ancol film by graphen oxide

2020 ◽  
Vol 4 (2) ◽  
pp. First
Author(s):  
Nguyen Tuong Vy ◽  
Le Ha Vu Duy
Keyword(s):  
Thermal Stability ◽  
Graphene Oxide ◽  
Young Modulus ◽  
Barrier Properties ◽  
Nanocomposite Films ◽  
Oxide Material ◽  
Gravimetric Analysis ◽  
X Ray Diffraction ◽  
Good Thermal Stability ◽  
Modified Hummers Method

In this study, graphene oxide (GO) is synthesized by a modified Hummers method, Polyvinyl alcohol (PVA) films and PVA/ GO nanocomposite films are prepared by casting stable aqueous mixed solutions. X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM) showed that there were a good compatibility and dispersion of graphene oxide (GO) on PVA matrix. In addition, nanocomposite films reinforced graphene oxide with the content of only 0.6 % phr have had 10.11% higher tensile strength, 12.24 % greater Young modulus, and significantly reduced water permeability during 4 hours of continuous immersion. Nanocomposite films maintained good thermal stability despite being added with graphene oxide, a material that is considered to have low thermal stability that easily decomposes below 200 oC, so thermal gravimetric analysis diagram (TGA) of PVA/ GO almost did not show a change compared to the neat PVA film. Initial results show that the efficiency of dispersing and reinforcing graphene oxide material on PVA resins has ameliorated the drawbacks of this polymer and contributed to extending the application of PVA in many areas. This has also reached closer to the goal of cleaning the environment by replacing non-biodegradable polymer sources with more friendly polymers.

Ultrasonic Degradation Performance of the CeZrMo Heteropoly Salt with Keggin Structure

2012 ◽  
Vol 518-523 ◽  
pp. 2965-2968
Author(s):  
Zhi Hong Zhang ◽  
Feng Xue
Keyword(s):  
Thermal Stability ◽  
Degradation Rate ◽  
Keggin Structure ◽  
Molecular Formula ◽  
Ultrasonic Frequency ◽  
Gravimetric Analysis ◽  
Ultrasonic Power ◽  
X Ray Diffraction ◽  
Crystal Water ◽  
Good Thermal Stability

A new heteropoly salt with Keggin structure of the 1:1:11 series had been synthesized, and characterized the structure by the foruier transform infrared spectroscopy (IR), ultraviolet spectra (UV) and X-ray diffraction (XRD).The thermal stability and the number of the crystal water was analyzed by the thermal gravimetric analysis/differential thermal analysis (TG/DTA). It was showed the molecular formula was Na5[Ce(ZrMo11O39)]•16H2O( Abbrev.CeZrMo),it possessed Keggin structure and had good thermal stability. The influences on the degradation rate, such as the amount of the CeZrMo, the initial concentration of the AGB dye wastewater, the ultrasonic frequency and power, were investigated. The results showed that the degradation rate could reach 88.01% after 60min irradiation, when the amount of the CeZrMo was 0.8g•L-1, the concentration of the AGB was 10mg•L-1, the ultrasonic frequency was 45kHz and the ultrasonic power was 100W.

Ultrasonic Degradation Performance of the NiZrMo Heteropoly Salt with Keggin Structure

2012 ◽  
Vol 178-181 ◽  
pp. 623-626
Author(s):  
Zhi Hong Zhang ◽  
Zhi Wei Guo
Keyword(s):  
Thermal Stability ◽  
Degradation Rate ◽  
Keggin Structure ◽  
Molecular Formula ◽  
Ultrasonic Frequency ◽  
Gravimetric Analysis ◽  
Ultrasonic Power ◽  
X Ray Diffraction ◽  
Crystal Water ◽  
Good Thermal Stability

A new heteropoly salt with Keggin structure of the 1:1:11 series had been synthesized, and characterized the structure by the foruier transform infrared spectroscopy (IR), ultraviolet spectra (UV) and X-ray diffraction (XRD).The thermal stability and the number of the crystal water was analyzed by the thermal gravimetric analysis/differential thermal analysis (TG/DTA). It was showed the molecular formula was Na6[Ni(ZrMo11O39)]•20H2O( Abbrev.NiZrMo),it possessed Keggin structure and had good thermal stability. The influences on the degradation rate, such as the amount of the NiZrMo, the initial concentration of the AGB dye wastewater, the ultrasonic frequency and power, were investigated. The results showed that the degradation rate could reach 90.19% after 60min irradiation, when the amount of the NiZrMo was 0.8g•L-1, the concentration of the AGB was 10mg•L-1, the ultrasonic frequency was 40kHz and the ultrasonic power was 80W.

scholarly journals Thermally Reduced Graphene Oxide/Thermoplastic Polyurethane Nanocomposites: Mechanical and Barrier Properties

Polymers ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 85
Author(s):  
Santiago Maldonado-Magnere ◽  
Mehrdad Yazdani-Pedram ◽  
Héctor Aguilar-Bolados ◽  
Raul Quijada
Keyword(s):  
Graphene Oxide ◽  
Thermoplastic Polyurethane ◽  
Young Modulus ◽  
Barrier Properties ◽  
Thermal Reduction ◽  
X Ray Diffraction ◽  
Graphene Oxides ◽  
Melt Mixing ◽  
Mixing Processes ◽  
Reduced Graphene

This work consists of studying the influence of two thermally reduced graphene oxides (TRGOs), containing oxygen levels of 15.8% and 8.9%, as fillers on the barrier properties of thermoplastic polyurethane (TPU) nanocomposites prepared by melt-mixing processes. The oxygen contents of the TRGOs were obtained by carrying out the thermal reduction of graphene oxide (GO) at 600 °C and 1000 °C, respectively. The presence and contents of oxygen in the TRGO samples were determined by XPS and their structural differences were determined by using X-ray diffraction analysis and Raman spectroscopy. In spite of the decrease of the elongation at break of the nanocomposites, the Young modulus was increased by up to 320% with the addition of TRGO. The barrier properties of the nanocomposites were enhanced as was evidenced by the decrease of the permeability to oxygen, which reached levels as low as −46.1%.

Improved mechanical and barrier properties of low-density polyethylene nanocomposite films by incorporating hydrophobic graphene oxide nanosheets

RSC Advances ◽  
2015 ◽  
Vol 5 (98) ◽  
pp. 80739-80748 ◽  
Author(s):  
Hua-Dong Huang ◽  
Sheng-Yang Zhou ◽  
Peng-Gang Ren ◽  
Xu Ji ◽  
Zhong-Ming Li
Keyword(s):  
Graphene Oxide ◽  
Barrier Properties ◽  
Nanocomposite Films ◽  
Low Density Polyethylene ◽  
Packaging Materials ◽  
Low Density ◽  
Graphene Oxide Nanosheets

The successful conversion from hydrophilic GONSs to hydrophobic ODA–GONSs imparts LDPE nanocomposite films with enhanced mechanical and barrier performances for potential packaging materials.

Nanocomposite Films of Poly(vinyl alcohol)-Grafted Graphene Oxide/Poly(vinyl alcohol) for Gas Barrier Film Applications

2015 ◽  
Vol 15 (10) ◽  
pp. 8348-8352 ◽  
Author(s):  
Min Eui Lee ◽  
Hyoung-Joon Jin
Keyword(s):  
Graphene Oxide ◽  
Vinyl Alcohol ◽  
Transmission Rate ◽  
Barrier Properties ◽  
Nanocomposite Films ◽  
Strong Interactions ◽  
Poly Vinyl Alcohol ◽  
Gas Barrier ◽  
Oxygen Transmission Rate ◽  
Gas Barrier Properties

Poly(vinyl alcohol) (PVA) composites containing graphene oxide (GO) functionalized with PVA were synthesized via the esterification of the carboxylic groups of GO. The presence of PVA-grafted GO (PVA-g-GO) in the PVA matrix induced strong interactions between the chains of the PVA matrix and allowed the PVA-g-GO to be uniformly dispersed throughout the matrix. The grafting of PVA to GO increased the gas barrier properties of the GO/PVA composites because of the increased compatibility between GO and PVA. The PVA-g-GO/PVA composites were used to coat the surface of poly(ethylene terephthalate) films. These coated films exhibited excellent gas barrier properties; the film containing 0.3 wt% of PVA-g-GO had an oxygen transmission rate (OTR) of 0.025 cc/(m2 · day) and an optical transmittance of 83.8%. As a result, PVA-g-GO/PVA composites that exhibited enhanced gas barrier properties were prepared with a solution mixing method.

Pd/SiO2 Organic-Inorganic Hybrid Materials by Sol-Gel Method: Preparation and Thermal Stability under H2 Atmosphere

2015 ◽  
Vol 1118 ◽  
pp. 20-27
Author(s):  
Jing Yang ◽  
Bao Song Li ◽  
Xiang Huo ◽  
Hao Xu ◽  
Hai Yun Hou
Keyword(s):  
Thermal Stability ◽  
Calcination Temperature ◽  
Hybrid Materials ◽  
Photoelectron Spectroscopy ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
Inorganic Hybrid ◽  
X Ray ◽  
Good Thermal Stability ◽  
Pd Doping

Pd/SiO2 organic-inorganic hybrid materials were prepared by adding PdCl2 into methyl-modified silica sol. The Pd/SiO2 hybrid materials were characterized by X-ray diffraction (XRD), fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS). The effects of calcination temperature and Pd-doping on the phase transition of Pd element and the thermal stability of CH3 group in the Pd/SiO2 organic-inorganic hybrid materials were investigated. The results showed that the reduced metallic Pd0 exhibits good thermal stability under H2 atmosphere in the calcination process. Pd element in noncalcined Pd/SiO2 materials exists in PdCl2 form, calcination at 200 °C in a H2 atmosphere produces some metallic Pd0 and calcinations at 350 °C results in the complete transformation of Pd2+ to metallic Pd0. With the increase of calcination temperature, the Pd0 particle sizes increase and the hydrophobic Si−CH3 bands decrease in intensity. As the calcination temperature is greater than or equal to 350 °C, the loading of metallic Pd0 nearly has no influence on the chemical structure but, with the increase of Pd content, the formed Pd0 particle size increases. To keep the hydrophobicity of Pd/SiO2 membrane materials, the optimal calcination temperature is about 350 °C under H2 atmosphere.

scholarly journals Stable Organic-Inorganic Hybrid Bismuth-Halide Monocrystalline Compounds With Adjustable Optoelectronic Properties

2021 ◽  
Author(s):  
Xinru Hu ◽  
Jilin Wang ◽  
Jian He ◽  
Guoyuan Zheng ◽  
Disheng Yao ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Room Temperature ◽  
Diffuse Reflectance ◽  
Decomposition Temperature ◽  
X Ray Diffraction ◽  
Monoclinic System ◽  
X Ray ◽  
Good Thermal Stability ◽  
Chemical Groups ◽  
Thermal Stability Of

Abstract Two kinds of novel organic-inorganic bismuth-halide hybrid monocrystalline compounds (C6H5CH2NH3)2BiCl5 and (C6H5CH2NH3)BiI4 were synthesized and characterized. The crystal structure, intermolecular interaction, morphology, chemical groups and bonds, optical and thermal stability of the samples were systematically investigated through single crystal X-ray diffraction, Hirshfeld surface analysis, SEM, FTIR, TG and UV-vis diffuse reflectance spectra. The results indicated that (C6H5CH2NH3)2BiCl5 and (C6H5CH2NH3)BiI4 crystals displayed a monoclinic system with the space group P21/c and P21/n at room temperature, respectively. These materials showed strong absorption in the ultraviolet and visible light regions, resulting in very low Eg, which could be continuously adjustable from 1.67 eV to 3.21 eV by changing the halogen ratio. In addition, these hybrid materials also exhibited good thermal stability. The decomposition temperature of (C6H5CH2NH3)2BiCl5 and (C6H5CH2NH3)BiI4 were 260℃ and 300℃ respectively. Therefore, these organic-inorganic bismuth-halide hybrid compounds have excellent development potential in the field of solar cell research.

Buckling of Two-Dimensional Covalent Organic Frameworks Under Thermal Stress

2019 ◽  
Author(s):  
Austin Evans ◽  
Matthew Ryder ◽  
Nathan C. Flanders ◽  
Edon Vitaku ◽  
Lin Chen ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Thermal Stress ◽  
Density Functional ◽  
Structural Changes ◽  
Gravimetric Analysis ◽  
Two Dimensional ◽  
Covalent Organic Frameworks ◽  
X Ray Diffraction ◽  
Excellent Thermal Stability ◽  
X Ray

Two-dimensional Covalent organic frameworks (2D COFs) are periodic, permanently porous, and lightweight solids that are polymerized from topologically designed monomers. The predictable design and structural modularity of these materials make them promising candidates for applications including catalysis, environmental remediation, chemical separations, and organic electronics, many of which will require stability to mechanical and thermal stress. Based on their reinforced structures and high degradation temperatures as determined by thermal gravimetric analysis (TGA), many reports have claimed that COFs have excellent thermal stability. However, their stability to heat and pressure has not been probed using methods that report on structural changes rather than the loss of volatile compounds. Here we explore two structurally analogous 2D COFs with different polymerization chemistries using in operando X-ray diffraction, which demonstrates the loss of crystallinity at lower temperatures than the degradation temperatures measured by TGA. Density functional theory calculations suggest that an asymmetric buckling of the COF lattice is responsible for the observed loss of crystallinity. In addition to their thermal stability, x-ray diffraction of the 2D COFs under gas pressures up to 100 bar showed no loss in crystallinity or structural changes, indicating that these materials are robust to mechanical stress by applied pressure. We expect that these results will encourage further exploration of COF stability as a function of framework design and isolated form, which will guide the design of frameworks that withstand demanding application-relevant conditions.

Sequence Effects on Properties of the Poly(p-phenylene terephthalamide)-based Macroinitiators and their Comb-like Copolymers Grafted by Polystyrene Side Chains

2014 ◽  
Vol 67 (1) ◽  
pp. 39 ◽  
Author(s):  
Shuming Du ◽  
Jie Zhang ◽  
Yan Guan ◽  
Xinhua Wan
Keyword(s):  
Thermal Stability ◽  
Graft Copolymers ◽  
Side Chains ◽  
Gravimetric Analysis ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Terephthaloyl Chloride ◽  
Discernible Effect ◽  
Sequence Effects ◽  
Concentrated Sulfuric Acid

Two poly(p-phenylene terephthalamide) (PPTA)-based macroinitiators with random and alternate sequences, i.e. poly(p-phenylene terephthalamide)-ran-poly[p-phenylene (2,2,6,6-tetramethylpiperidinyl-1-oxy)terephthalamide)] (CPPTA-ran) and poly(p-phenylene terephthalamide)-alt-poly[p-phenylene (2,2,6,6-tetramethylpiperidinyl-1-oxy)terephthalamide)] (CPPTA-alt), were prepared via copolycondensation of terephthaloyl chloride, 2,2,6,6-tetramethylpiperidinyl-1-oxy (TEMPO)-functionalized terephthaloyl chloride, and p-phenylenediamine. The graft copolymers consisting of rigid PPTA backbones and polystyrene side chains were obtained by nitroxide-mediated radical polymerization. Both macroinitiators and graft copolymers were characterized by thermal gravimetric analysis, differential scanning calorimetry, wide-angle X-ray diffraction, and polarized optical microscopy. The regular incorporation of the TEMPO-containing co-unit gives rise to remarkable effects on the thermal stability, lyotropic liquid crystallinity, and macromolecular packing in bulk. CPPTA-alt shows better thermal stability and more ordered intermolecular structure than CPPTA-ran. The former generates a nematic phase at a concentration of 18 wt-% in concentrated sulfuric acid, whereas the latter does so at a concentration of 12 wt-%. For the graft copolymers, the alternative main chains exhibit sharper diffraction than the random ones. However, the sequence change exerts no discernible effect on other properties.

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