chemical foaming
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2022 ◽  
Author(s):  
Mahboobeh Monjezi ◽  
Vahid Javanbakht

Abstract Geopolymers as sustainable and environmentally friendly “green materials”, can be synthesized by utilizing waste material and by-products. A porous geopolymer foam adsorbent based on ZSM-5 zeolite was prepared using templating emulsion/chemical foaming method in different conditions and used for dye removal in batch and continuous systems. The parameters affecting the dye adsorption including temperature, concentration, and pH, kinetics, isotherm, and thermodynamics of the process were investigated. The results of the geopolymer foam synthesis showed that thermal pretreatment of the zeolite has a positive effect on the strength and adsorption capacity. Moreover, the increase in sodium silicate more than the stoichiometric reduces the strength and adsorption capacity. The findings obtained from the batch adsorption process showed that the adsorption kinetics of the pseudo-second-order model and the adsorption isotherm of the Temkin model is adjusted with the experimental data. Thermodynamic results indicated that the process of dye adsorption with geopolymer foam is exothermic. The results from continuous experiments indicated more compatibility of the adsorption process with the models of Thomas and Bohart-Adams. The maximum adsorption capacity of methylene blue in batch and continuous processes was 9.82 and 8.17 mg/g. The adsorbent reduction was performed successfully by chemical and thermal processes.


Friction ◽  
2021 ◽  
Author(s):  
Chang Li ◽  
Jie Fei ◽  
Enzhi Zhou ◽  
Rui Lu ◽  
Xiaohang Cai ◽  
...  

AbstractPaper-based friction materials are porous materials that exhibit anisotropy; they exhibit random pore sizes and quantities during their preparation, thereby rendering the control of their pore structure difficult. Composites with different pore structures are obtained by introducing chemical foaming technology during their preparation to regulate their pore structure and investigate the effect of pore structure on the properties of paper-based friction materials. The results indicate that the skeleton density, total pore area, average pore diameter, and porosity of the materials increase after chemical foaming treatment, showing a more open pore structure. The addition of an organic chemical foaming agent improves the curing degree of the matrix significantly. Consequently, the thermal stability of the materials improves significantly, and the hardness and elastic modulus of the matrix increase by 73.7% and 49.4%, respectively. The dynamic friction coefficient increases and the wear rate is reduced considerably after optimizing the pore structure. The wear rate, in particular, decreases by 47.7% from 2.83 × 10−8 to 1.48 × 10−8 cm3/J as the foaming agent content increases. Most importantly, this study provides an effective method to regulate the pore structure of wet friction materials, which is conducive to achieving the desired tribological properties.


Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2207
Author(s):  
Żaneta Garczyk ◽  
Zbigniew Jaegermann ◽  
Piotr Duda ◽  
Andrzej S. Swinarew ◽  
Sebastian Stach

The main aim of this study was to analyze microtomographic data to determine the geometric dimensions of a ceramic porous material’s internal structure. Samples of a porous corundum biomaterial were the research material. The samples were prepared by chemical foaming and were measured using an X-ray scanner. In the next stage, 3D images of the samples were generated and analyzed using Thermo Scientific Avizo software. The analysis enabled the isolation of individual pores. Then, the parameters characterizing the pore geometry and the porosity of the samples were calculated. The last part of the research consisted of verifying the developed method by comparing the obtained results with the parameters obtained from the microscopic examinations of the biomaterial. The comparison of the results confirmed the correctness of the developed method. The developed methodology can be used to analyze biomaterial samples to assess the geometric dimensions of biomaterial pores.


2020 ◽  
pp. 0021955X2095930
Author(s):  
J Guillén-Mallette ◽  
PI González-Chi ◽  
RH Cruz-Estrada ◽  
RN Miranda-Flores y ◽  
MA Rivero-Ayala

Recycling printed polypropylene (PP) labels and printed polyolefins (PO) caps as a chemical foaming agent to produce foam products is studied. An experimental Taguchi L16 design with seven experimental variables involved is used: talc content and screw angular velocity, at four experimental levels; extrusion temperature profile and extruded formulations, at three levels; and, type of label washing process, the use of metal mesh and the type of label drying process, at two levels. As control variables, the morphology of the cells and the density of the foamed products are utilized. The labels/caps mixture was composed of 21% printed PP labels and 79% printed polyolefin caps. Part of the pigments from the ink labels and some polar groups of low-molecular-weight materials present in the molten polymer were partially decomposed at the PP processing temperatures, which contributes to the cell formation and growth of the extruded foams. The labels/caps mixture generated large ellipsoidal and elongated cells (740 µm) oriented in the extrusion direction because of the presence of high density polyethylene (HDPE) and EVA in the recycled PP caps and labels. The experimental factors that influenced the foam density were the screw angular velocity and temperature, and the cell morphology depended on the matrix crystallinity and melt strength.


2020 ◽  
Vol 9 (10) ◽  
pp. 1433-1438
Author(s):  
Podchara Rattanakawin ◽  
Kenji Yoshimoto ◽  
Yuta Hikima ◽  
Alvin Chandra ◽  
Teruaki Hayakawa ◽  
...  

2020 ◽  
pp. 0021955X2095022
Author(s):  
Shuai Li ◽  
Xuemei Sun ◽  
Rui Wang ◽  
Yanyan Hu ◽  
Xiaofei Ma ◽  
...  

By using a standard stretch spline as the research object, the influence of gas counter pressure (GCP) technology on melt foaming behavior in chemical foaming injection molding (CFIM) process was investigated. Related experimental line for GCP assisted CFIM foam was designed, and the effect of GCP technology on melt flow front, spline surface quality and internal cell was studied. According to the results obtained from the experiment, two critical GCP pressures and one critical GCP holding time were innovation proposed. Two critical GCP pressures are the critical GCP pressure of melt flow front cell not cracking and the critical GCP pressure of melt not foaming, respectively. The critical GCP holding time is the secondary foaming behavior time. Based on the proposed critical GCP pressures and critical GCP holding time, the influence mechanism of GCP technology on melt foaming action during CFIM process was revealed.


2020 ◽  
Vol 60 (5) ◽  
pp. 482-485
Author(s):  
V. V. Kozlov ◽  
A. P. Shevchik ◽  
S. A. Suvorov ◽  
N. V. Arbuzova

2019 ◽  
Vol 32 (5) ◽  
pp. 693-698 ◽  
Author(s):  
Podchara Rattanakawin ◽  
Kai Yamamura ◽  
Kenji Yoshimoto ◽  
Masahiro Ohshima

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