Effect of the particle diameter of the chemical foaming agent on the foaming process and the cellular structure of one-shot compression molded polyethylene foams

2018 ◽  
Vol 38 (1) ◽  
pp. 41-50 ◽  
Author(s):  
Junichiro Tateishi ◽  
Tsuyoshi Nishiwaki ◽  
Sathish K. Sukumaran ◽  
Masataka Sugimoto
Keyword(s):  
Thermal Decomposition ◽  
Time Dependence ◽  
Cellular Structure ◽  
Particle Diameter ◽  
Cavity Pressure ◽  
Number Density ◽  
Foaming Agent ◽  
Proportionality Constant ◽  
Foaming Process ◽  
Chemical Foaming

Abstract We investigated the effect of varying the particle diameter and the particle content of a chemical foaming agent on the foaming process and the cellular structure of one-shot compression molded polyethylene foams. We foamed metallocene linear low-density polyethylene (LLDPE) crosslinked by dicumyl peroxide using azodicarbonamide (ADCA) as the foaming agent. We used a purpose-built metal mold equipped with a built-in pressure sensor to monitor the time evolution of the cavity pressure. The time dependence of the cavity pressure, which is indicative of the thermal decomposition of the ADCA, was s-shaped. The s-shaped time dependence of the cavity pressure indicates that, after an initial induction phase during which there is no thermal decomposition of the ADCA, the ADCA rapidly decomposes until the reaction is essentially complete. The cavity pressure at saturation, which corresponds to the mass of the generated gas, was linearly proportional to the ADCA content but only weakly dependent on the particle diameter of the ADCA. Upon decreasing the particle diameter of ADCA, rise in the cavity pressure at intermediate times, which indicates the thermal decomposition of the ADCA, began earlier and was faster. The cell size in the final foam decreased with a decrease in the particle diameter of the ADCA. The cell number density in the unfoamed samples (NF) was proportional to the ADCA particle number density in the unfoamed samples (NC), with a proportionality constant less than 1. A model for the foaming process where the ADCA particles nucleate cells and the nucleated cells then coalesce, thereby reducing the number of remaining cells, can offer an explanation for the observed proportionality between NF and NC and the proportionality constant being less than 1. Furthermore, it is proposed that cell coalescence occurs if the increase in the moduli of the LLDPE due to crosslinking is not sufficient to prevent the coalescence of the cells triggered by the rapid increase in the cavity pressure due to the rapid decomposition of ADCA.

Analogues of the active and inactive sodium carbonate

1982 ◽  
Vol 47 (12) ◽  
pp. 3348-3361 ◽  
Author(s):  
Erich Lippert ◽  
Karel Mocek ◽  
Emerich Erdös
Keyword(s):  
Thermal Decomposition ◽  
Time Dependence ◽  
Water Vapour ◽  
Sulphur Dioxide ◽  
Atmospheric Pressure ◽  
Flow Reactor ◽  
Kinetic Measurements ◽  
Sodium Potassium ◽  
Alkaline Metals ◽  
Hydrogen Carbonates

The reactivity of the anhydrous carbonates of alkaline metals with sulphur dioxide has been studied experimentally in dependence both on the nature of the cation and on the way of preparation of the anhydrous carbonate. The carbonates were prepared either by thermal decomposition of hydrogen carbonates or by thermal dehydration of carbonate hydrates. The carbonates of lithium, sodium, potassium, rubidium and caesium have been investigated. Kinetic measurements were carried out in a flow reactor in the integral regime at 423 K under atmospheric pressure, with a gas containing 0.2 vol.% of sulphur dioxide and 2.0 vol.% of water vapour in the nitrogen as a carrier gas. The reactivities have been compared on the basis of time dependence of the conversion of carbonate to sulphite.

scholarly journals In-situ measurement of internal mold pressure during one-shot chemical foaming process

Seikei-Kakou ◽  
2017 ◽  
Vol 29 (2) ◽  
pp. 62-68
Author(s):  
Junichiro Tateishi ◽  
Norihiko Taniguchi ◽  
Tsuyoshi Nishiwaki ◽  
Sukumaran Sathish K. ◽  
Masataka Sugimoto
Keyword(s):  
In Situ Measurement ◽  
Internal Mold ◽  
Foaming Process ◽  
Chemical Foaming

USE OF THE MICROWAVE ENERGY FOR ALUMINUM WASTE FOAMING

2019 ◽  
Vol 25 (4) ◽  
pp. 43-49
Author(s):  
LUCIAN PAUNESCU ◽  
MARIUS FLORIN DRAGOESCU ◽  
SORIN MIRCEA AXINTE ◽  
ANA CASANDRA SEBE
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
Porous Structure ◽  
Powder Mixture ◽  
Aluminum Foam ◽  
Fine Powder ◽  
Microwave Energy ◽  
Raw Material ◽  
Foaming Agent ◽  
Foaming Process

The paper presents an aluminum foam experimental technique using the microwave energy. The raw material was recycling aluminum waste processed by ecological melting and gas atomizing to obtain the fine powder required in the foaming process. The powder mixture was completed with dolomite as a foaming agent. The products had a fine and homogeneous porous structure (pore size between 0.4-0.9 mm). The density (1.17-1.19 g/cm3), the compressive strength (6.83-7.01 MPa) and the thermal conductivity (5.71-5.84 W/m·K) had values almost similar to the foams made by conventional methods.

scholarly journals Effect of Ammonium Nitrate on Nanoparticle Size Reduction

2008 ◽  
Vol 2008 ◽  
pp. 1-4 ◽  
Author(s):  
Kalyana C. Pingali ◽  
Shuguang Deng ◽  
David A. Rockstraw
Keyword(s):  
Ammonium Nitrate ◽  
Metallic Nanoparticles ◽  
Particle Diameter ◽  
Feed Solution ◽  
Pyrolysis Process ◽  
Foaming Agent ◽  
Aerosol Droplet ◽  
Order Of Magnitude ◽  
Spray Pyrolysis Process ◽  
20 Nm

Ammonium nitrate was added to the spraying solution as a foaming agent to reduce the particle size of nanoparticles synthesized in the spray-pyrolysis process. Ammonium nitrate was effective in breaking the aerosol droplet size and generating nanoparticles that were of approximately one order-of-magnitude (from 200 to 20 nm) smaller diameter than those created in the absence of ammonium nitrate in the feed solution. This technique makes it possible to control the particle diameter of metallic nanoparticles below 20 nm.

scholarly journals Numerical Simulation of the Distribution of In Situ Cigarette Combustion-Generated Particulate Matter

2020 ◽  
Vol 4 (4) ◽  
pp. 59
Author(s):  
Shi Chen ◽  
Hanqing Liu ◽  
Zhiguo Sun ◽  
Hongyong Xie
Keyword(s):  
Mathematical Model ◽  
Particulate Matter ◽  
Cigarette Smoke ◽  
Cross Section ◽  
Constant Pressure ◽  
Particle Diameter ◽  
Axial Position ◽  
Number Density ◽  
Total Particulate Matter

This paper has established a two-dimensional (2D) mathematical model for the generation, growth, and deposition of cigarette total particulate matter (TPM) in the smoldering state. The model has covered the chemical reactions and mass transfer as well as the mechanism of generation, flow, and condensation of particulate matter inside a burning cigarette. Cigarette smoke was generated by puffing under a constant pressure, and the pressure of the filter outlet was −274 Pa. The peak of the concentration of particulate matter was spatially overlapped with the peaks of pyrolysis and oxidation. Pertaining to the cross section of the cigarette at the same axial position, the peak of the diameter of particulate matter along the radial distribution first appeared in the zone near the edge of the cigarette cross section, and then gradually moved to the center of the cigarette with the cigarette smoke moving away from the combustion cone. The maximum number density of particulate matter calculated by the 2D mathematical model at the same axial position of the cigarette and the corresponding particle diameter, as well as the filtration efficiency of the filter rod, are in good accordance with the experimental data reported in previous studies.

Research on the Performance of Plaster Material by Chemical Foaming Method

2013 ◽  
Vol 830 ◽  
pp. 435-438
Author(s):  
Hong Xia Wang ◽  
Bo Liu ◽  
Kuang Ping Yuan ◽  
Wu Biao Duan ◽  
Fei Hua Yang ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Flexural Strength ◽  
Water Temperature ◽  
Chemical Reaction ◽  
Raw Material ◽  
Foaming Agent ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Chemical Foaming

The paper introduces a kind of foaming plaster with main raw material of α- gypsum, which is produced by utilizing the chemical reaction principles H2O2 was decomposed. Meanwhile，study the changes of density，flexural strength and compressive strength of plaster material performance with the additives in different ratio. The result showed that water-cement ratio, H2O2 foaming agent and water temperature all affect the performance of the foaming plaster.

Porous Material Production and Material Properties

2019 ◽  
Vol 946 ◽  
pp. 84-90
Author(s):  
Liudmila Shtirc ◽  
Svetlana G. Vlasova ◽  
Dmitry Meshcherskikh
Keyword(s):  
Porous Material ◽  
Caustic Soda ◽  
Material Properties ◽  
Foaming Agent ◽  
Experimental Glass ◽  
Material Production ◽  
Foaming Process ◽  
Foaming Temperature ◽  
Glass Compositions

In our work we defined two directions for synthesizing porous material: pulping selected experimental glass compositions and using caustic soda as a foaming agent. We studied the foaming temperature settings, investigated the porous material properties. The intensity of the foaming process was estimated from the value of the foaming coefficient.

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