scholarly journals Effects of laminating and co-firing conditions on the performance of anode-supported Ce0.8Sm0.201.9 film electrolyte

2011 ◽  
Vol 43 (3) ◽  
pp. 305-312 ◽  
Author(s):  
X. Li ◽  
J. Lu ◽  
H. Wang
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Flexural Strength ◽  
Single Cell ◽  
Open Circuit Voltage ◽  
Open Circuit ◽  
Maximum Power Density ◽  
Film Electrolyte ◽  
Different Temperatures

In order to evaluate the laminating and co-firing technique on the performance of anode-supported Ce0.8Sm0.2O1.9 (SDC) film electrolyte and its single cell, NiO-YSZ and NiOSDC anode-supported SDC film electrolytes were fabricated by laminating 24 sheets of anode plus one sheet of electrolyte and co-firing. La0.4Sr0.6Co0.2Fe0.8O3-? (LSCF)-SDC cathode was coated on the SDC electrolytes to form a single cell. The lamination was tried at different laminating temperatures and pressures and the co-firing was carried out at different temperatures. The results showed that the laminating temperature should above the glass transition temperature (Tg) of the binder. The laminating pressure of 70 MPa resulted in warp of the samples. The best co-firing temperature of the anode-supported SDC film electrolyte was 1400?C. The SDC film electrolyte formed well adherence to the anode. The NiO-YSZ anode had larger flexural strength than the NiO-SDC anode. The NiO-YSZ anode-supported SDC film electrolyte single cell had an open circuit voltage of 0.803 V and a maximum power density of 93.03 mW/cm2 with hydrogen as fuel at 800?C.

scholarly journals Hydrophobically Modified Isosorbide Dimethacrylates as a Bisphenol-A (BPA)-Free Dental Filling Material

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2139
Author(s):  
Bilal Marie ◽  
Raymond Clark ◽  
Tim Gillece ◽  
Seher Ozkan ◽  
Michael Jaffe ◽  
...  
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Flexural Strength ◽  
Bisphenol A ◽  
Water Sorption ◽  
Triethylene Glycol ◽  
Filling Material ◽  
Hydrophobically Modified ◽  
Free Replacement

A series of bio-based hydrophobically modified isosorbide dimethacrylates, with para-, meta-, and ortho- benzoate aromatic spacers (ISBGBMA), are synthesized, characterized, and evaluated as potential dental restorative resins. The new monomers, isosorbide 2,5-bis(4-glyceryloxybenzoate) dimethacrylate (ISB4GBMA), isosorbide 2,5-bis(3-glyceryloxybenzoate) dimethacrylate (ISB3GBMA), and isosorbide 2,5-bis(2-glyceryloxybenzoate) dimethacrylate (ISB2GBMA), are mixed with triethylene glycol dimethacrylate (TEGDMA) and photopolymerized. The resulting polymers are evaluated for the degree of monomeric conversion, polymerization shrinkage, water sorption, glass transition temperature, and flexural strength. Isosorbide glycerolate dimethacrylate (ISDGMA) is synthesized, and Bisphenol A glycerolate dimethacrylate (BisGMA) is prepared, and both are evaluated as a reference. Poly(ISBGBMA/TEGDMA) series shows lower water sorption (39–44 µg/mm3) over Poly(ISDGMA/TEGDMA) (73 µg/mm3) but higher than Poly(BisGMA/TEGDMA) (26 µg/mm3). Flexural strength is higher for Poly(ISBGBMA/TEGDMA) series (37–45 MPa) over Poly(ISDGMA/TEGDMA) (10 MPa) and less than Poly(BisGMA/TEGDMA) (53 MPa) after immersion in phosphate-buffered saline (DPBS) for 24 h. Poly(ISB2GBMA/TEGDMA) has the highest glass transition temperature at 85 °C, and its monomeric mixture has the lowest viscosity at 0.62 Pa·s, among the (ISBGBMA/TEGDMA) polymers and monomer mixtures. Collectively, this data suggests that the ortho ISBGBMA monomer is a potential bio-based, BPA-free replacement for BisGMA, and could be the focus for future study.

Reliability of Low Glass Transition Temperature COTS PEM’s for Space Applications

2003 ◽  
Author(s):  
M. Sandor ◽  
S. Agarwal ◽  
D. Peters ◽  
M. S. Cooper
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Flame Retardants ◽  
Measurement Techniques ◽  
Test Results ◽  
Space Applications ◽  
Molding Compound ◽  
Different Temperatures ◽  
Compound Materials

Microcircuit manufacturers of Plastic Encapsulated Microcircuits (PEM’s) have made changes in epoxy molding compound materials and chemistry, which lower Glass Transition Temperature (Tg). PEM users in harsh environments have concerns if either the part in its application, or in evaluation or assembly, is used close to, or above, the Tg. Various Tg measurement techniques are available and discussed. Test results from one technique is reviewed. The implications of the Tg results on usage of these parts in space applications will be presented. Burn-in/ reliability test results of samples with low Tg PEM’s will be presented. The reliability experiments include testing under different temperatures. The issue being addressed is whether outgassing of molding compounds occurs when the temperature of the molding compound exceeds the Tg. This is a caution noted by many vendors. As an example outgassing of flame retardants can degrade parametric performance and wire bond integrity. This would be the case when PEMS are being qualified for Space applications using burn-in or in storage environments. JPL’s past experience has shown that COTS PEMS parametrics can degrade significantly even when the burn-in temperature is well below the Tg. Two different microcircuits exhibiting low Tg were evaluated. Assessment of final electrical test measurements and yield are shown.

scholarly journals The Glass Transition Temperature and Temperature Dependence of Activation Energy of Viscous Flow of Ovalbumin

2016 ◽  
Vol 39 (1) ◽  
pp. 13-25
Author(s):  
Karol Monkos
Keyword(s):  
Activation Energy ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Viscous Flow ◽  
Solvent Interactions ◽  
Model Free ◽  
Free Volume Model ◽  
Wide Range ◽  
Different Temperatures

Abstract The paper presents the results of viscosity determinations on aqueous solutions of ovalbumin at a wide range of concentrations and at temperatures ranging from 5°C to 55°C. On the basis of these measurements and three models of viscosity for glass-forming liquids: Avramov’s model, free-volume model and power-law model, the activation energy of viscous flow for solutions and ovalbumin molecules, at different temperatures, was calculated. The obtained results show that activation energy monotonically decreases with increasing temperature both for solutions and ovalbumin molecules. The influence of the energy of translational heat motion, protein-protein and protein-solvent interactions, flexibility and hydrodynamic radius of ovalbumin on the rate of decrease in activation energy with temperature has been discussed. One of the parameters in the Avramov’s equation is the glass transition temperature Tg. It turns out that the Tg of ovalbumin solutions increases with increasing concentration. To obtain the glass transition temperature of the dry ovalbumin, a modified Gordon-Taylor equation is used. Thus determined the glass transition temperature for dry ovalbumin is equal to (231.8 ± 6.1) K.

scholarly journals Construction of a TTT-η Diagram of High-Refractive Polyurethane Based on Curing Kinetics

Polymers ◽  
2021 ◽  
Vol 13 (20) ◽  
pp. 3474
Author(s):  
Shidi Huang ◽  
Guiming Zhang ◽  
Weiping Du ◽  
Huifang Chen
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Gelation Time ◽  
Curing Kinetics ◽  
Processing Parameters ◽  
Curing Process ◽  
Scanning Calorimetry ◽  
Different Temperatures ◽  
Temperature Transformation

A time–temperature–transformation–viscosity (TTT-η) diagram can reflect changes in the physical states of a resin, which take on significance for the study of the curing process of polyurethane resin lenses. Coupling the differential scanning calorimetry (DSC) test, the curing kinetic parameters of 1,4-bis(isocyanatomethyl)cyclohexane (H6XDI)/2,3-bis((2-mercaptoethyl)thio)-1-propanethiol (BES) polyurethane system were obtained. By phenomenological modeling, the relationships between degree, temperature, and time were obtained. An isothermal DSC test was carried out at 423 K. Based on the DiBenedetto equation, the relationships between glass transition temperature, degree of cure, and time were obtained, and the glass transition temperature was thus correlated with temperature and time. The gelation time at different temperatures was measured by rotary rheometry, and the relationship between gelation time and gelation temperature was established. The time–temperature–transformation (TTT) diagram of H6XDI/BES system was constructed accordingly. Subsequently, a six-parameter double Arrhenius equation was used as the basis for the rheological study. The viscosity was examined during the curing process. The TTT-η diagram was obtained, which laid the theoretical foundation for the optimization and setting of processing parameters.

Fabrication of Laminated Nanocomposites by Vacuum-Assisted Deposition of Clay Onto Glass/Epoxy Prepregs

2006 ◽  
Author(s):  
Levent Aktas ◽  
M. Cengiz Altan
Keyword(s):  
Mechanical Properties ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Flexural Strength ◽  
Microstructural Characterization ◽  
Flexural Stiffness ◽  
Matrix Composites ◽  
Deposition Chamber ◽  
Nanoclay Content

In this study we are presenting a novel method for introducing nanoclay in epoxy matrix composites. The method involves vacuum-assisted deposition of fine clay particles directly onto the surface of commercially available prepregs. A deposition chamber is developed that is capable of breaking down nanoclay particles by subjecting them to shear and depositing them uniformly onto prepregs at room temperature. By using the deposition chamber, a thin layer of nanoclay is deposited on 101.6mm×101.6mm woven glass/epoxy prepregs. Twelve of these prepregs are stacked and cured by an autoclave at a temperature of 121°C under a constant pressure of 0.2MPa (30psi) for 1 hour. After the curing is complete, the laminates are cut into 10.8mm×31.7mm samples for three-point bending tests, glass transition temperature measurements and microstructural characterization. The improvements in mechanical properties such as flexural strength, flexural stiffness, and glass transition temperature by the addition of nanoclay are presented. Nanocomposite morphology is studied by light microscopy and scanning electron microscopy. Marginal improvements in mechanical properties are observed with only 0.6% nanoclay content. The flexural stiffness improved by 4% while maintaining the flexural strength constant at around 400Wa. Glass transition temperature is measured as 128°C for samples with and without nanoclay. However, significant differences in microstructure are observed. Although both samples contain micro-voids, these voids are observed to be more extensive in samples involving nanoclay.

Novel Applications of the QCM Technique in Biomaterials Science

2007 ◽  
Vol 1060 ◽  
Author(s):  
Candida Costa Silva ◽  
David C Lin ◽  
Iren Horkayne-Szakaly ◽  
Peter J Basser ◽  
Ferenc Horkay
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Vinyl Acetate ◽  
Reasonable Agreement ◽  
Quartz Crystal ◽  
Vapor Sorption ◽  
Different Temperatures ◽  
Novel Applications ◽  
Quartz Sensor

ABSTRACTA quartz crystal microbalance (QCM) has been used to investigate polymer samples. The vapor sorption of three different polymer samples (poly(vinyl acetate), polybutadiene and polydimethylsiloxane) was studied. The change in resonance frequency of the quartz sensor uniformly coated with polymer films was measured as a function of the film thickness and water absorption at different temperatures. The range of linear frequency vs. mass response was determined in the absence of absorbed water. The glass transition temperature of thin poly(vinyl acetate) films (10 nm <thickness< 1000 nm) was found to be in reasonable agreement with published values for macroscopic samples.

Fabrication of an Anode-Supported Sofc with a Sol-Gel Coating Method for a Mixed-Gas Fuel Cell

2005 ◽  
Vol 277-279 ◽  
pp. 455-461 ◽  
Author(s):  
Nguyen Xuan Phuong Vo ◽  
Sung Pil Yoon ◽  
Suk Woo Nam ◽  
Jong Hee Han ◽  
Tae Hoon Lim ◽  
...  
Keyword(s):  
Thin Film ◽  
Fuel Cell ◽  
Single Cell ◽  
Power Density ◽  
Open Circuit Voltage ◽  
Sol Gel ◽  
Open Circuit ◽  
Maximum Power ◽  
Maximum Power Density ◽  
Mixed Gas

An anode-supported type solid oxide fuel cell (SOFC) is a promising structure resulting in a very high performance because it consists of a very thin electrolyte. In the preliminary stage, we have succeeded in the fabrication of Samaria-Doped Ceria (SDC) thin film on a porous Ni-Al substrate using a sol-gel coating technique. The thin electrolyte film binds the substrate well and a single cell made with the SDC thin-film electrolyte and porous LSM cathode exhibited a good performance in a mixed-gas condition, even at intermediate temperatures. The single cell, consisting of 20 µm thin SDC electrolytes, the porous Ni-Al anode substrate, and a LSM cathode, exhibited an open circuit voltage of 0.82V and a maximum power density of 0.31 W.cm-2 at 700°C with humidified methane and air mixtures. This cell also generated an open circuit voltage of about 1.1V and a maximum power density of 0.34 W.cm-2 at 600°C with humidified hydrogen as the fuel and air as the oxidant.

scholarly journals Thermal and Mechanical Properties of Vinyl Ester Hybrid Composites with Carbon Black and Glass Reinforcement

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Geetanjali S. Guggari ◽  
S. Shivakumar ◽  
G. A. Manjunath ◽  
R. Nikhil ◽  
Alagar Karthick ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Flexural Strength ◽  
Carbon Black ◽  
Vinyl Ester ◽  
Flexural Modulus ◽  
Thermal And Mechanical Properties ◽  
Degradation Temperature

The objective of the work is to investigate both thermal and mechanical properties of vinyl ester/glass composites incorporated with different percentages of carbon black reinforcements through experimental approaches. Analysis of glass transition temperature, thermogravimetric analysis (TGA), degradation temperature, hardness, flexural strength, etc. is performed using differential scanning calorimeter, X-ray diffraction, tensile machine, and flexural machine, respectively. The scanning electron microscope was used for surface fracture studies. The degradation temperature reduces initially with the percentage of carbon black and then increases. Glass transition temperature increases with the percentage of carbon black while above 500°C temperature, the weight percentage of composite drops. The results also reveal that 4% of carbon with vinyl ester improved the tensile strength by 30%, hardness by 35%, flexural strength by 45%, flexural modulus by 66%, and interlaminate shear strength by 44% when compared with the other percentage of carbon black.

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