scholarly journals Viscoelastic epoxy foams by an aqueous emulsion foaming process

2019 ◽  
Vol 56 (1) ◽  
pp. 105-118
Author(s):  
Du Ngoc Uy Lan ◽  
Muhammad Syazwan Fauzi ◽  
Cao Xuan Viet ◽  
Daniel Raps ◽  
Volker Altstädt
Keyword(s):  
Sodium Bicarbonate ◽  
High Speed ◽  
Water Molecules ◽  
Aqueous Emulsion ◽  
Blowing Agent ◽  
Compression Set ◽  
Foaming Process ◽  
A Cell ◽  
Viscoelastic Foams ◽  
Emulsifying Ability

The research proposed an aqueous emulsion foaming process to produce a viscoelastic epoxy foam having a density of 0.33–0.36 g/cm3 from the polyamide–epoxy adduct, which uses a reverse ratio of epoxy and polyamide hardener. The process is simple, economical and uses no surfactant, thanks to the emulsifying ability of polyamide hardener. Firstly, the mixture of excess polyamide, epoxy and sodium bicarbonate was emulsified with distilled water using high-speed stirring to form dispersed epoxy droplets in water. Secondly, a solution of ammonium chloride was added, which reacted with sodium bicarbonate to produce carbon dioxide and ammonia gases dispersed in the epoxy emulsion. The expanding gases induced flocculation and partial coalescence of the epoxy droplets; sequentially water molecules were entrapped within them. Finally, a curing process was carried out to stabilise the foam morphology and structure. Two types of pore morphologies were observed: a large foam-pore generated from blowing-agent gases and a cell-wall pore formed from the vapourisation of entrapped water (as the void template). Porosity and pore morphologies depended on blowing-agent content, and the viscoelasticity was affected by the epoxy/polyamide ratio. The obtained viscoelastic foams showed a large number of interconnected cells and exhibited high compression set values.

Utilization of electrical charges in the pores of tofu waste for hydrogen production in water

2020 ◽  
pp. 124-135
Author(s):  
I. N. G. Wardana ◽  
N. Willy Satrio
Keyword(s):  
Magnetic Field ◽  
Hydrogen Production ◽  
Sodium Bicarbonate ◽  
Positive Charge ◽  
Electrical Energy ◽  
Hydrogen Sensor ◽  
Water Molecules ◽  
Partial Charge ◽  
Delocalized Electron ◽  
Water Hydrogen

Tofu is main food in Indonesia and its waste generally pollutes the waters. This study aims to change the waste into energy by utilizing the electric charge in the pores of tofu waste to produce hydrogen in water. The tofu pore is negatively charged and the surface surrounding the pore has a positive charge. The positive and negative electric charges stretch water molecules that have a partial charge. With the addition of a 12V electrical energy during electrolysis, water breaks down into hydrogen. The test was conducted on pre-treated tofu waste suspension using oxalic acid. The hydrogen concentration was measured by a MQ-8 hydrogen sensor. The result shows that the addition of turmeric together with sodium bicarbonate to tofu waste in water, hydrogen production increased more than four times. This is due to the fact that magnetic field generated by delocalized electron in aromatic ring in turmeric energizes all electrons in the pores of tofu waste, in the sodium bicarbonate, and in water that boosts hydrogen production. At the same time the stronger partial charge in natrium bicarbonate shields the hydrogen proton from strong attraction of tofu pores. These two combined effect are very powerful for larger hydrogen production in water by tofu waste.

Compressive Deformation and Energy Absorption Characteristics of Conductive Carbon Black Reinforced Microcellular EPDM Vulcanizates

2005 ◽  
Vol 24 (4) ◽  
pp. 209-222 ◽  
Author(s):  
S.P. Mahapatra ◽  
D.K. Tripathy
Keyword(s):  
Carbon Black ◽  
Compressive Stress ◽  
Energy Absorption ◽  
Filler Loading ◽  
Maximum Efficiency ◽  
Stress Strain ◽  
Blowing Agent ◽  
Compression Set ◽  
Rate Dependent ◽  
Conductive Carbon Black

Compressive stress-strain properties of unfilled and conductive carbon black (VulcanXC 72) filled oil extended EPDM (keltan 7341A) microcellular vulcanizates were studied as a function of blowing agent (density) and filler loading. With decrease in density, the compressive stress-strain curves for microcellular vulcanizates behaved differently from those of solid vulcanizates. The compressive stress-strain properties were found to be strain rate dependent. The log-log plots of relative density of the microcellular vulcanizates showed a fairly linear correlation with the relative modulus. The compression set at a constant stress increased with decrease in density. The efficiency of energy absorption E, was also studied as a function of filler and blowing agent loading. From the compressive stress-strain plots the efficiency E and the ideality parameter I, were evaluated. These parameters were plotted against stress to obtain maximum efficiency and the maximum ideality region, which will make these materials suitable for cushioning and packaging applications in electronic devices.

The Influence of Sodium Bicarbonate Loading as Blowing Agent on the Properties of Epoxy Foam

2018 ◽  
Vol 280 ◽  
pp. 270-276 ◽  
Author(s):  
Mohamad Saed Hussein ◽  
Teh Pei Leng ◽  
Abdul Razak Rahmat ◽  
Firuz Zainuddin ◽  
Yeoh Chow Keat
Keyword(s):  
Sodium Bicarbonate ◽  
Low Cost ◽  
Flexural Properties ◽  
Foaming Agent ◽  
Blowing Agent ◽  
Environmental Friendly ◽  
Epoxy Foam ◽  
Mixing Method ◽  
Porosity Percentage ◽  
Thermosetting Epoxy

This research studied the effect of sodium bicarbonate content on the properties of epoxy. Sodium bicarbonate (SB) was used as foaming agent to improve the properties of thermosetting epoxy resin. The samples of epoxy foam were produced using mixing method. Sodium bicarbonate was selected as blowing agent by reason of the environmental friendly and low cost concern. Mechanical, physical and morphology properties were done. Sodium bicarbonate content was varied at 5, 10, 15, 20 and 25 part per hundred (phr), respectively. It can be highlighted that the optimum content of the SB was selected at 15 phr and it gave the moderate porosity percentage (%), and moderate value in mechanical and density properties, higher SB content exhibited lower flexural properties.

scholarly journals The effect of sodium bicarbonate as blowing agent on the mechanical properties of epoxy

2019 ◽  
Vol 16 ◽  
pp. 1622-1629 ◽  
Author(s):  
Mohamad Saed Hussein ◽  
Teh Pei Leng ◽  
Abdul Razak Rahmat ◽  
Firuz Zainuddin ◽  
Yeoh Cheow Keat ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Sodium Bicarbonate ◽  
Blowing Agent

scholarly journals Development of a High-speed Eigenvalue-solver for Constant Plasma Monitoring on a Cell Cluster System

2011 ◽  
Vol 4 ◽  
pp. 898-907
Author(s):  
Noriyuki Kushida ◽  
Ken-ichi Fujibayashi ◽  
Hiroshi Takemiya
Keyword(s):  
High Speed ◽  
Cluster System ◽  
Cell Cluster ◽  
A Cell ◽  
Plasma Monitoring ◽  
Eigenvalue Solver

Bringing it All Back Home

2007 ◽  
Vol 17 (1) ◽  
pp. 163-172 ◽  
Author(s):  
Peter Whalley
Keyword(s):  
Cell Phone ◽  
High Speed ◽  
Independent Contractor ◽  
Fully Integrated ◽  
Time Zones ◽  
A Cell ◽  
At Home ◽  
Older Child

ABSTRACT:Not so long ago I interviewed a computer engineer in her home. Surrounded with toys and a napping baby—the interview time had been chosen carefully—she talked about how she worked as an independent contractor for a large electronics company. Connected by high-speed broadband, two telephone lines, and a cell phone, she felt fully integrated into the work, exchanging electronic files with her colleagues and having telephone conversations with customers two continents and umpteen time zones away. She told me she often worked late after the baby was in bed and during the baby's afternoon nap before she went to pick her older child up from school. Despite these odd working times, however, she was convinced that none of the company's customers and only some of her work colleagues knew that she worked at home. She was very contented with the arrangement.

Electrical Characteristics Analysis of Bonded Cells for Shingled Modules

2020 ◽  
Vol 20 (11) ◽  
pp. 6653-6658
Author(s):  
Jeong Eun Park ◽  
So Mang Park ◽  
Won Seok Choi ◽  
Jae Joon Jang ◽  
Donggun Lim
Keyword(s):  
Laser Cutting ◽  
High Speed ◽  
Green Laser ◽  
Curing Temperature ◽  
Process Conditions ◽  
Laser Process ◽  
Cut Cell ◽  
Electrically Conductive Adhesive ◽  
Characteristics Analysis ◽  
A Cell

A shingled module fabricated using electrically conductive adhesive (ECA) can increase the light-receiving area and provide greater power than a conventional module fabricated using solder-coated copper ribbons. However, several issues such as damage from laser cutting and poor contact by the conductive paste may arise. In this study, a 15.675 × 3.1 cm2 c-Si cut cell was fabricated using a nanosecond green laser, and cell bonding was performed using ECA to fabricate shingled modules. If the laser process was performed with high speed and low power, there was insufficient depth for cut cell fabrication. This was because the laser only had a thermal effect on the surface. The cell was processed to a depth of approximately 46 μm by the laser, and it could be seen that the laser cutting proceeded smoothly when the laser process affected more than 25% of the wafer thickness. The cut cell was bonded by ECA, and the process conditions were changed. The highest efficiency of 20.27% was obtained for a cell bonded under the conditions of a curing time of 60 s and curing temperature of 150°C. As a result, the efficiency of the bonded cell was increased by approximately 2.67% compared to the efficiency of the conventional cut cell. This was because the shadow loss due to the busbar was reduced, increasing the active area of the module by eliminating the busbar from the illuminated area.

The Influence of the Foaming Agents on the Porosity of the PM Hydroxyapatite-Based Biocomposites Processed by Two-Step Sintering

2015 ◽  
Vol 1128 ◽  
pp. 178-186
Author(s):  
Cristina Teișanu ◽  
Carmen Ristoscu ◽  
Gabriela Sima
Keyword(s):  
Foaming Agent ◽  
Foaming Agents ◽  
Space Holder ◽  
Blowing Agent ◽  
Foaming Process ◽  
Eds Analysis ◽  
Titanium Hydride Powder ◽  
The Matrix ◽  
Powder Particles ◽  
Hydride Powder

This paper presents a comparative analysis of the foaming process developed in hydroxyapatite (HAp)-based bicomposites as a function of the foaming agent. The matrix of the biocomposite consists of either submicronic or micronic powder particles of HAp. The titanium hydride powder was added as reinforcement’s precursor as well as blowing agent, and in order to increase the biocomposites’ porosity calcium carbonate was added as space holder agent. The powders mixture was homogenized in a planetary ball mill with a single grinding bowl for 1 minute in air. Uniaxial cold compaction at 120-170 MPa was performed in order to obtain cylindrical green parts, which next were heated in argon atmosphere using the two step sintering technique at temperatures of 900 °C for 1 minute and 800°C for 450 - 600 minutes. The porosity of the biocomposite is analysed through calculations and SEM and EDS analysis highlighting the influence of the above mentioned foaming techniques (blowing and space holder).

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