scholarly journals Efficient Synthesis of PVDF/PI Side-by-Side Bicomponent Nanofiber Membrane with Enhanced Mechanical Strength and Good Thermal Stability

Nanomaterials ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 39 ◽  
Author(s):  
Ming Cai ◽  
Hongwei He ◽  
Xiao Zhang ◽  
Xu Yan ◽  
Jianxin Li ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Thermal Stability ◽  
Mechanical Strength ◽  
Polyvinylidene Fluoride ◽  
Chemical Structure ◽  
Electrospun Fiber ◽  
Nanofiber Membrane ◽  
Application Range ◽  
Good Thermal Stability ◽  
Filtration Properties

Bicomponent composite fibers, due to their unique versatility, have attracted great attention in many fields, such as filtration, energy, and bioengineering. Herein, we efficiently fabricated polyvinylidene fluoride/polyimide (PVDF/PI) side-by-side bicomponent nanofibers based on electrospinning, which resulted in the synergism between PVDF and PI, and eventually obtained the effect of 1 + 1 > 2. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were used to characterize the morphology and chemical structure of nanofibers, indicating that a large number of side-by-side nanofibers were successfully prepared. Further, the thermal stability, mechanical strength, and filtration properties of PVDF/PI were carefully investigated. The results revealed that the bicomponent nanofibers possessed both good mechanical strength and remarkable thermal stability. Moreover, the mechanical properties of PVDF/ PI were strengthened by more than twice after the heat treatment (7.28 MPa at 25 °C, 15.49 MPa at 230 °C). Simultaneously, after the heat treatment at 230 °C for 30 min, the filtration efficiency of PVDF/PI membrane was maintained at about 95.45 ± 1.09%, and the pressure drop was relatively low. Therefore, the prepared PVDF/PI side-by-side bicomponent nanofibers have a favorable prospect of application in the field of medium- and high-temperature filtration, which further expands the application range of electrospun fiber membranes.

Effect of Heat Treatment on Mechanical Properties of ECAPed 7075 Aluminum Alloy

2013 ◽  
Vol 829 ◽  
pp. 62-66 ◽  
Author(s):  
Alireza Fallahi ◽  
Hossein Hosseini-Toudeshky ◽  
Seyed Mahmoud Ghalehbandi
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Thermal Stability ◽  
Aluminum Alloy ◽  
Solution Treatment ◽  
7075 Aluminum Alloy ◽  
Ecap Processing ◽  
Good Thermal Stability ◽  
7075 Alloy

It is the objective of this study to investigate the effect of ECAP processing and heat treatment on the mechanical properties of the UFG 7075 alloy. Also the effect of post ECAP heat treatment is investigated. The alloy is processed by ECAP after annealing as well as solution treatment to produce an UFG structure. Furthermore mechanical properties and their variations during annealing and aging are investigated. The hardness of the pre-ECAP annealed and the pre-ECAP solutionised 7075 aluminum alloy has increased significantly compared with that of the CG sample. Also hardness of ECAPed specimen has not experienced significant changes in post-ECAP heat treatment and indicated that the alloy had approximately good thermal stability.

scholarly journals Thermal characterization of novel aliphatic polyesters with ether and thioether linkages

e-Polymers ◽  
2010 ◽  
Vol 10 (1) ◽  
Author(s):  
M. Soccio ◽  
N. Lotti ◽  
L. Finelli ◽  
A. Munari
Keyword(s):  
Thermal Stability ◽  
Molecular Weight ◽  
Chemical Structure ◽  
Room Temperature ◽  
Crystallization Rate ◽  
Thermal Characterization ◽  
Scanning Calorimetry ◽  
Aliphatic Polyesters ◽  
Good Thermal Stability

AbstractSeveral novel ether or thioether linkage containing aliphatic polyesters and poly(alkylene dicarboxylate)s were synthesized for comparison and characterized in terms of chemical structure and molecular weight. The thermal behavior was examined by thermogravimetric analysis and differential scanning calorimetry. All the polymers showed a good thermal stability, even though lower for the ether or thioether linkage-containing polyesters. The decrement of the thermal stability appears to be more relevant in the case of the presence of sulphur atoms. At room temperature the samples appeared semicrystalline, except PTTDG and PDEDG, which were viscous oils; the effect of the introduction of ether or thioether group was an increment of the Tgvalue, a decrement of the melting temperature and a significant decrease of the crystallization rate. The entity of the variations was found to be affected by the kind of group introduced, and the trend observed can be explained on the basis of atom electronegativity and dimensions

Conductive Polyaniline and Paper Reinforced Composites

2014 ◽  
Vol 556-562 ◽  
pp. 123-126
Author(s):  
Jin Hua Yan ◽  
Ren Mei Xu ◽  
Na Yun
Keyword(s):  
Thermal Stability ◽  
Mechanical Strength ◽  
Interfacial Polymerization ◽  
Lower Surface ◽  
Paper Substrate ◽  
Oh Groups ◽  
Good Thermal Stability ◽  
Conductive Composites ◽  
Novel Method ◽  
Conductive Polyaniline

A novel method of direct aniline multi-interfacial polymerization on paper substrate is introduced in this paper. Cellulose base papers with and without PAE reinforced were discussed. The PANI-paper composites after more than 3 polymerizations had much lower surface resistivity. Their mechanical strength and thermal stability were analyzed by tensile test and GTA. FTIR results explained that there was strong interaction between NH groups in aniline monomers and OH groups in fibers. Conductive composites made with PAE treated paper had both good thermal stability and good mechanical strength with high conductivity.

scholarly journals On the Solubility and Stability of Polyvinylidene Fluoride

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1354
Author(s):  
Jean E. Marshall ◽  
Anna Zhenova ◽  
Samuel Roberts ◽  
Tabitha Petchey ◽  
Pengcheng Zhu ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Dielectric Constant ◽  
Circular Economy ◽  
Polyvinylidene Fluoride ◽  
High Dielectric Constant ◽  
Widespread Application ◽  
Good Thermal Stability ◽  
Carbon Backbone ◽  
Crystal Phases ◽  
High Dielectric

This literature review covers the solubility and processability of fluoropolymer polyvinylidine fluoride (PVDF). Fluoropolymers consist of a carbon backbone chain with multiple connected C–F bonds; they are typically nonreactive and nontoxic and have good thermal stability. Their processing, recycling and reuse are rapidly becoming more important to the circular economy as fluoropolymers find widespread application in diverse sectors including construction, automotive engineering and electronics. The partially fluorinated polymer PVDF is in strong demand in all of these areas; in addition to its desirable inertness, which is typical of most fluoropolymers, it also has a high dielectric constant and can be ferroelectric in some of its crystal phases. However, processing and reusing PVDF is a challenging task, and this is partly due to its limited solubility. This review begins with a discussion on the useful properties and applications of PVDF, followed by a discussion on the known solvents and diluents of PVDF and how it can be formed into membranes. Finally, we explore the limitations of PVDF’s chemical and thermal stability, with a discussion on conditions under which it can degrade. Our aim is to provide a condensed overview that will be of use to both chemists and engineers who need to work with PVDF.

scholarly journals Thermostable manganese (II) dependent α-glycosidase from Pseudothermotoga thermarum

BioResources ◽  
2019 ◽  
Vol 14 (3) ◽  
pp. 7266-7274
Author(s):  
Hao Shi ◽  
Yue Liu ◽  
Jiannan Guo ◽  
Yang Cao ◽  
Xianyan Zhu ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Thermal Stability ◽  
Gel Filtration ◽  
Recombinant Enzyme ◽  
Relative Molecular Mass ◽  
Optimal Temperature ◽  
Good Thermal Stability ◽  
E Coli ◽  
Purification System ◽  
Optimal Ph

Alpha-glycosidase degrades polysaccharides and oligosaccharides and participates in the synthesis of oligosaccharides through a process called transglycosylation. In this study, an α-glycosidase gene pthgly from Pseudothermotoga thermarum was cloned using pET-20b as a vector and was expressed in E. coli BL21(DE3). After heat treatment and affinity chromatography, the resulting recombinant enzyme was purified. The purity of the enzyme reached a single band at a molecular weight of approximately 55 kDa. The properties of the recombinant enzyme were determined. The optimal temperature of α-glycosidase (Pthgly) was 90 °C and the optimal pH was 7.5. In addition, Pthgly exhibited good thermal stability at 70 °C and 75 °C. The relative molecular mass of the recombinant enzyme was 116 kDa, as determined by a protein purification system with a gel filtration column. Furthermore, α-glycosidase possessed Michaelis-Menten kinetics with a Km and Vmax of 0.29 ± 0.01 mmol l-1 and 22.12 ± 1.31 μmol min-1 mg-1, respectively.

Polyimides based on Poly(4-furanyl-butan-2-one)

1992 ◽  
Vol 4 (1) ◽  
pp. 19-33 ◽  
Author(s):  
Hasmukh S. Patel ◽  
Harshad D. Patel
Keyword(s):  
Thermal Stability ◽  
Acetic Anhydride ◽  
Mechanical Strength ◽  
Elemental Analysis ◽  
Diels Alder ◽  
Spectral Studies ◽  
Good Thermal Stability ◽  
Glass Reinforcement

Polyimides were prepared by Diels-Alder (DA) reaction of furfuralacetone (FAC) resin [poly(4-furanyl-butan-2-one)] with various bismaleimides. The DA reaction was carried out in tetrahydrofuran (THF) as solvent as well as in bulk, followed by aromatization of the tetrahydrophthalimide intermediates in the presence of acetic anhydride. All the polyimides were characterized by elemental analysis, IR spectral studies and thermogravimetry. The results show that polyimides based on FAC resin exhibit good thermal stability. Preliminary tests for glass reinforcement of the polyimides indicate that laminates with good mechanical strength can be prepared.

TEXTURE AND STRUCTURE VARIATION OF PEROVSKITE LaFeO3/ZSM-5 DURING HIGH-TEMPERATURE DESULFURIZATION

2019 ◽  
Vol 27 (05) ◽  
pp. 1950151
Author(s):  
DONGJING LIU ◽  
WEIGUO ZHOU ◽  
JIANG WU
Keyword(s):  
Heat Treatment ◽  
Activation Energy ◽  
Thermal Stability ◽  
High Temperature ◽  
High Temperatures ◽  
Textural Property ◽  
Structure Variation ◽  
Good Thermal Stability ◽  
Sulfur Capacity

Perovskite LaFeO3/ZSM-5 is synthesized via citrate route for H2S removal at high temperatures. It shows good thermal stability after heat treatment at 500–700∘C with respect to slight changes in crystallographic phase and textural property. It presents the optimal desulfurization performance at 600∘C with sulfur capacity of 1017[Formula: see text][Formula: see text]mol[Formula: see text]S/g and products of S, LaS2, and Fe7S8. Sulfidation at 500∘C yields the same products as sulfidation at 600∘C but displays the lowest sulfur capacity of 408[Formula: see text][Formula: see text]mol[Formula: see text]S/g. Sulfidation at 700∘C produces La2O2S, Fe3S4, and unreacted LaFeO3. The activation energy of the sulfidation reaction over LaFeO3/ZSM-5 is 109.6[Formula: see text]kJ/mol.

scholarly journals Analysis of Thermal–Mechanical Properties of Silicon Dioxide/Polyvinylidene Fluoride Reinforced Non-Woven Fabric (Polypropylene) Composites

Polymers ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 481 ◽  
Author(s):  
Fangyun Kong ◽  
Mengzhou Chang ◽  
Zhenqing Wang
Keyword(s):  
Thermal Stability ◽  
Silicon Dioxide ◽  
Composite Film ◽  
Polyvinylidene Fluoride ◽  
Lithium Ion ◽  
Woven Fabric ◽  
Thermal Shrinkage ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Good Thermal Stability

In this paper, solution casting method is used to prepare the PP (polypropylene) non-woven fabric based composite film filled with silicon dioxide/polyvinylidene fluoride (SiO2/PVDF). The mechanical and thermodynamic properties of PP/SiO2/PVDF composites were studied by a uniaxial tensile test under different temperature and combustion experiment. It is found that the stress of PP/SiO2/PVDF composite film with 4 wt % SiO2 is the maximum value, reaching 18.314 MPa, 244.42% higher than that of pure PP non-woven. Meanwhile, the thermal–mechanical coupling tests indicate that with the increase of temperature, the ultimate stress and strain of the composite decrease. At the same time, the thermal shrinkage property of the composite during the heating process is studied. The modified composite has good thermal stability under 180 °C. Scanning electron microscope (SEM), X-ray diffraction (XRD) and thermogravimetric (TG) were used to characterize the pore shape, distribution and crystal phase change of the composite. The modified PP/SiO2/PVDF composite film structure shows high strength and good thermal stability, and can better meet the requirements of strength and thermal performance of lithium-ion battery during the charging and discharging process.

Thermal characterization of novel aliphatic polyesters with ether and thioether linkages

e-Polymers ◽  
2011 ◽  
Vol 11 (1) ◽  
Author(s):  
M. Soccio ◽  
N. Lotti ◽  
L. Finelli ◽  
A. Munari
Keyword(s):  
Thermal Stability ◽  
Molecular Weight ◽  
Chemical Structure ◽  
Room Temperature ◽  
Crystallization Rate ◽  
Thermal Characterization ◽  
Scanning Calorimetry ◽  
Aliphatic Polyesters ◽  
Good Thermal Stability

AbstractSeveral novel ether or thioether linkage containing aliphatic polyesters and poly(alkylene dicarboxylate)s for comparison were synthesized and characterized in terms of chemical structure and molecular weight. The thermal behavior was examined by thermogravimetric analysis and differential scanning calorimetry. All the polymers showed a good thermal stability, even though lower for the ether or thioether linkage-containing polyesters. The decrement of the thermal stability appears to be more relevant in the case of presence of sulphur atoms. At room temperature the samples appeared semicrystalline, except PTTDG and PDEDG, which were viscous oils; the effect of the introduction of ether or thioether group was an increment of the Tg value, a decrement of the melting temperature and a significant decrease of the crystallization rate. The entity of the variations was found to be affected by the kind of group introduced, and the trend observed can be explained on the basis of atom electronegativity and dimensions.

Thermal Stability and Mechanical Properties of Plasma Sprayed Al2O3/ZrO2 Nano-Composite Coating

2006 ◽  
Vol 317-318 ◽  
pp. 513-516 ◽  
Author(s):  
Satoshi Sodeoka ◽  
Masato Suzuki ◽  
Takahiro Inoue
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Thermal Stability ◽  
Composite Coating ◽  
Grain Growth ◽  
Nano Composite ◽  
Good Thermal Stability ◽  
Fine Powders ◽  
Nano Composite Coating ◽  
Plasma Sprayed

Alumina/zirconia nano-composite coating was fabricated by plasma spraying using agglomerated feedstock from fine powders of about 100 nm. The coating was consisted of fine γ-alumina and zirconia crystals with size of several nano meter and some amorphous boundary layers. The amorphous phase was crystallized and disappeared after heat treatment at 930°C. However, the crystallite size was kept under 50 nm even after 1500°C-100hr heating, so the alumina-zirconia nano-composite showed good thermal stability against the grain growth.

Sign in / Sign up

Export Citation Format

Share Document