The Effective Diffusivity of Cyclopentane and n-Pentane in PU and PUIR Foams by Thin-Slice Gravimetric Analysis

2020 ◽  
pp. 45-55
Author(s):  
J. Richard Booth ◽  
Deb Bhattacharjee
Keyword(s):  
Effective Diffusivity ◽  
Gravimetric Analysis ◽  
Thin Slice

scholarly journals Modelling of Mass Transfer Resistances in Non-uniformly Washcoated Monolith Reactors

2021 ◽  
Author(s):  
M. Walander ◽  
J. Sjöblom ◽  
D. Creaser ◽  
B. Agri ◽  
N. Löfgren ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Elevated Temperatures ◽  
Effective Diffusivity ◽  
Gravimetric Analysis ◽  
New Model ◽  
Modelling Framework ◽  
Local Material ◽  
Monolith Reactors ◽  
1D Model ◽  
Local Material Properties

AbstractThere are various methodologies to account for mass transfer within non-uniformly distributed washcoats in monolith reactors in 1D models (axially). However, 1+1D models (axially/radially) fail to capture local variations in mass transfer from different coating thicknesses or cracks. In this paper, we present a novel way to account for local material properties in a washcoated monolith reactor. The suggested method uses an existing 1+1D modelling framework and sectionalizes the washcoat into multiple tangential segments which are solved independently. Intelligent gravimetric analysis and scanning electron microscopy are used in combination to calculate local effective diffusivity as an input for each simulation. The new model is compared to the original 1+1D model using NO light-off simulations. The new model predicted increased conversion at elevated temperatures, where mass transfer limitations are present, due to the higher porosity in the corners. The simulation time for each model was similar due to the parallelizable nature of the new model.

Mass Determination by Direct Measurement of Electron Scattering

1975 ◽  
Vol 33 ◽  
pp. 240-241
Author(s):  
M. K. Lamvik ◽  
A. V. Crewe
Keyword(s):  
Cross Section ◽  
Electron Scattering ◽  
Mass Density ◽  
Variable Mass ◽  
Scattering Cross Section ◽  
Mass Determination ◽  
Number Density ◽  
Cross Sectional ◽  
Thin Slice ◽  
Scattering Cross

If a molecule or atom of material has molecular weight A, the number density of such units is given by n=Nρ/A, where N is Avogadro's number and ρ is the mass density of the material. The amount of scattering from each unit can be written by assigning an imaginary cross-sectional area σ to each unit. If the current I0 is incident on a thin slice of material of thickness z and the current I remains unscattered, then the scattering cross-section σ is defined by I=IOnσz. For a specimen that is not thin, the definition must be applied to each imaginary thin slice and the result I/I0 =exp(-nσz) is obtained by integrating over the whole thickness. It is useful to separate the variable mass-thickness w=ρz from the other factors to yield I/I0 =exp(-sw), where s=Nσ/A is the scattering cross-section per unit mass.

Thin slice methodology: Variability in impressions from homogeneous and heterogeneous behavior sequences

2007 ◽  
Author(s):  
Matthew J. Lindberg ◽  
G. Daniel Lassiter ◽  
Katrina Brickner ◽  
James Mahnic ◽  
Melissa Smart
Keyword(s):  
Thin Slice ◽  
Heterogeneous Behavior ◽  
Behavior Sequences

Evaluation of the concentration of particulate material and its impact on the respiratory diseases of the workers of an artesanal smelting huarochirí. Lima

2018 ◽  
Vol 2 (1) ◽  
pp. 13
Author(s):  
Walter Manuel Vicharra ◽  
Carlos Cabrera
Keyword(s):  
Respiratory Diseases ◽  
San Antonio ◽  
Particulate Material ◽  
Quality Monitoring ◽  
Gravimetric Analysis ◽  
Air Quality Monitoring ◽  
Analysis Method ◽  
Particulate Materials ◽  
Health Assessments ◽  
Medical Examinations

The main objective of esta research is to determine the level of concentration of particulate materials of the size of 10 microns and 2.5 microns of an artisanal foundry, and to Evaluate the health in workers' respiratory diseases, as well as to find a relationship Between the particulate materials and the respiratory diseases, Which the project is located in the district of San Antonio, Department of Huarochiri, Department of Lima, Peru - 2017. The gravimetric analysis method approved by the General Directorate of Environmental Health DIGESA was used, with the Protocol for air quality monitoring and data management, to determine the level of concentration of particulate material and on the other hand Health Assessments in respiratory diseases Were used a survey made by a doctor in pulmonology, Which was Then backed by medical examinations performed on workers. It was Determined That the particulate materials of 10 microns and 2.5 microns Were above environmental quality standards, Which is Considered as risky for the health of people, and in respiratory diseases it was Concluded That some of the subjects of the population of study are With occupational diseases.

Thermal gravimetric analysis of in-situ crosslinked nanocellulose whiskers • poly(methyl vinyl ether-co-maleic acid) • polyethylene glycol

TAPPI Journal ◽  
2011 ◽  
Vol 10 (4) ◽  
pp. 29-33
Author(s):  
LEE A. GOETZ ◽  
AJI P. MATHEW ◽  
KRISTIINA OKSMAN ◽  
ARTHUR J. RAGAUSKAS
Keyword(s):  
Thermal Stability ◽  
Polyethylene Glycol ◽  
Vinyl Ether ◽  
Thermal Gravimetric Analysis ◽  
Maleic Acid ◽  
Gravimetric Analysis ◽  
Thermal Gravimetric ◽  
Methyl Vinyl ◽  
Methyl Vinyl Ether

The thermal stability and decomposition of in-situ crosslinked nanocellulose whiskers – poly(methyl vinyl ether-co-maleic acid) – polyethylene glycol formulations (PMVEMA-PEG), (25%, 50%, and 75% whiskers) – were investigated using thermal gravimetric analysis (TGA) methods. The thermal degradation behavior of the films varied according to the percent cellulose whiskers in each formulation. The presence of cellulose whiskers increased the thermal stability of the PMVEMA-PEG matrix.

Synthesis of Smart Mesoporous Materials

2003 ◽  
Vol 775 ◽  
Author(s):  
G.V.Rama Rao ◽  
Qiang Fu ◽  
Linnea K. Ista ◽  
Huifang Xu ◽  
S. Balamurugan ◽  
...  
Keyword(s):  
Mesoporous Silica ◽  
Mesoporous Materials ◽  
Fluorescent Dyes ◽  
Thermo Gravimetric Analysis ◽  
Molecular Transport ◽  
Solute Diffusion ◽  
Gravimetric Analysis ◽  
Stimuli Responsive ◽  
Porous Network ◽  
Hybrid Mesoporous Materials

AbstractThis study details development of hybrid mesoporous materials in which molecular transport through mesopores can be precisely controlled and reversibly modulated. Mesoporous silica materials formed by surfactant templating were modified by surface initiated atom transfer radical polymerization of poly(N-isopropyl acrylamide) (PNIPAAm) a stimuli responsive polymer (SRP) within the porous network. Thermo gravimetric analysis and FTIR spectroscopy were used to confirm the presence of PNIPAAm on the silica surface. Nitrogen porosimetry, transmission electron microscopy and X-ray diffraction analyses confirmed that polymerization occurred uniformly within the porous network. Uptake and release of fluorescent dyes from the particles was monitored by spectrofluorimetry and scanning laser confocal microscopy. Results suggest that the presence of PNIPAAm, a SRP, in the porous network can be used to modulate the transport of aqueous solutes. At low temperature, (e.g., room temperature) the PNIPAAm is hydrated and extended and inhibits transport of analytes; at higher temperatures (e.g., 50°C) it is hydrophobic and is collapsed within the pore network, thus allowing solute diffusion into or out of the mesoporous silica. The transition form hydrophilic to hydrophobic state on polymer grafted mesoporous membranes was determined by contact angle measurements. This work has implications for the development of materials for the selective control of transport of molecular solutes in a variety of applications.

Microhardness Testing on Via Fill Material for Via In Pad Technology

2003 ◽  
Author(s):  
Norman J. Armendariz ◽  
Carolyn McCormick
Keyword(s):  
Printed Circuit Board ◽  
Failure Modes ◽  
Strong Dependence ◽  
Circuit Board ◽  
Electrical Performance ◽  
Gravimetric Analysis ◽  
Passive Components ◽  
Root Cause ◽  
Fill Material ◽  
Signal Routing

Abstract Via in pad PCB (Printed Circuit board) technology for passive components such as chip capacitors and resistors, provides the potential for improved signal routing density and reduced PCB area. Because of these improvements there is the potential for PCB cost reduction as well as gains in electrical performance through reduced impedance and inductance. However, not long after the implementation, double digit unit failures for solder joint electrical opens due to capacitor “tombstoning” began to occur. Failure modes included via fill material (solder mask) protrusion from the via as well as “out gassing” and related “tombstoning.” This failure analysis involved investigating a strong dependence on PCB supplier and, less obviously, manufacturing site. Other factors evaluated included via fill material, drill size, via fill thermal history and via fill amount or fill percent. The factor most implicated was incomplete cure of the via fill material. Previous thermal gravimetric analysis methods to determine level of polymerization or cure did not provide an ability to measure and demonstrate via fill cure level in small selected areas or its link to the failures. As a result, there was a metrology approach developed to establish this link and root-cause the failures in the field, which was based on microhardness techniques and noncontact via fill measuring metrologies.

Coordination Compounds of Some 3d-Transition Metal Ions with N1-[4-(4-bromo-phenylsulfonyl)-benzoyl]-N4-(4-methoxyphenyl)- thiosemicarbazide

2008 ◽  
Vol 59 (7) ◽  
Author(s):  
Madalina Angelusiu ◽  
Maria Negoiu ◽  
Stefania-Felicia Barbuceanu ◽  
Tudor Rosu
Keyword(s):  
Coordination Compounds ◽  
Magnetic Moments ◽  
Thermo Gravimetric Analysis ◽  
Electronic Spectroscopy ◽  
Transition Metal Ions ◽  
Synthesis And Characterization ◽  
Gravimetric Analysis ◽  
Thermo Gravimetric ◽  
New Compounds

The paper presents the synthesis and characterization of Cu(II), Co(II), Ni(II), Cd(II), Zn(II) and Hg(II) complexes with N1-[4-(4-bromo-phenylsulfonyl)-benzoyl]-N4-(4-methoxyphenyl)-thiosemicarbazide. The new compounds were characterized by IR, EPR, electronic spectroscopy, magnetic moments, thermo-gravimetric analysis and elemental analysis.

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