Thermal Measurement of In-Situ and Thin-Specimen Aging of Experimental Polyisocyanurate Roof Insulation Foamed with Alternative Blowing Agents

2009 ◽  
pp. 142-142-25 ◽  
Author(s):  
JE Christian ◽  
GE Courville ◽  
RS Graves ◽  
RL Linkous ◽  
DL McElroy ◽  
...  
Keyword(s):  
Thermal Measurement ◽  
Thin Specimen ◽  
Blowing Agents

scholarly journals High Performance Attapulgite/Polypyrrole Nanocomposite Reinforced Polystyrene (PS) Foam Based on Supercritical CO2 Foaming

Polymers ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 985 ◽  
Author(s):  
Yidong Liu ◽  
Lingfeng Jian ◽  
Tianhua Xiao ◽  
Rongtao Liu ◽  
Shun Yi ◽  
...  
Keyword(s):  
Supercritical Co2 ◽  
High Performance ◽  
In Situ Polymerization ◽  
Compression Modulus ◽  
Blowing Agents ◽  
Foaming Process ◽  
Potential Applications ◽  
Polymerization Method ◽  
Low Solubility

CO2 has been regarded as one of the most promising blowing agents for polystyrene (PS) foam due to its non-flammability, low price, nontoxicity, and eco-friendliness. However, the low solubility and fast diffusivity of CO2 in PS hinder its potential applications. In this study, an attapulgite (ATP)/polypyrrole (PPy) nanocomposite was developed using the in situ polymerization method to generate the hierarchical cell texture for the PS foam based on the supercritical CO2 foaming. The results demonstrated that the nanocomposite could act as an efficient CO2 capturer enabling the random release of it during the foaming process. In contrast to the pure PS foam, the ATP/PPy nanocomposite reinforced PS foam is endowed with high cell density (up to 1.9 × 106) and similar thermal conductivity as the neat PS foam, as well as high compression modulus. Therefore, the in situ polymerized ATP/PPy nanocomposite makes supercritical CO2 foaming desired candidate to replace the widely used fluorocarbons and chlorofluorocarbons as PS blowing agents.

Expandable polystyrene without any embedded blowing agent

2020 ◽  
pp. 0021955X2094497
Author(s):  
Habib Haji Avdi ◽  
Morteza Nasiri ◽  
Mohammad Javad Tehrani ◽  
Maryam Alizadeh Aghdam ◽  
Farhang Abbasi
Keyword(s):  
Suspension Polymerization ◽  
Expansion Ratio ◽  
Scanning Calorimetry ◽  
Blowing Agents ◽  
Blowing Agent ◽  
Rate Of Polymerization ◽  
Polystyrene Matrix ◽  
Expandable Polystyrene ◽  
Before And After

In this research, in-situ suspension polymerization of styrene in the presence of graphene, without any blowing agent, was investigated. Steam used in the expansion process of graphene-filled expandable polystyrene (GEPS). The dispersed graphene nano-sheets in the polystyrene matrix may absorb water in high temperatures, which evaporates by lowering the pressure and expansion precedes. The effects of graphene type and loading and steam temperature on the expansion ratio evaluated. Scanning electron microscopy (SEM) used to reveal the cross-section morphologies before and after expansion. The effect of graphene on the polymerization kinetics evaluated by differential scanning calorimetry (DSC). The results showed that by increasing the graphene loading, the rate of polymerization decreased, and the expansion ratio increased. The highest expansion ratio of about 4.8 was for particles containing 0.4% of graphene. Therefore, it was shown that by using graphene as a dispersed phase, polystyrene particles expanded without any organic blowing agents. Here, the idea of expandable polymers without any embedded blowing agent is introduced, which eliminates the release of volatile organic compounds and makes the process environmentally friendly.

scholarly journals Energy Dependence of Amorphization of Ge by Kr Ions

1992 ◽  
Vol 279 ◽  
Author(s):  
R. C. Birtcher
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Energy Dependence ◽  
Defect Density ◽  
Thin Specimen ◽  
Ion Energy ◽  
Transmission Electron

ABSTRACTThin Ge specimens have been irradiated with Kr ions of different energies, and the dose required for complete amorphization determined by in situ transmission electron microscopy. Because Ge is directly amorphized by a single energetic Kr ion, onset of amorphization was detected after the lowesi ion doses. The Kr dose required for complete amorphization was found to increase linearly with ion energy over the range 0.5 MeV to 3.5 MeV. With the assumption that the defect density required for amorphization is independent of ion energy, the number of defects produced in a thin specimen by each ion decreases with increasing energy as the reciprocal of the incident ion energy. TRIM calculations indicate that there is a slight decrease in the amount of damage required with increasingion energy.

scholarly journals In situ TEM and synchrotron characterization of U–10Mo thin specimen annealed at the fast reactor temperature regime

2015 ◽  
Vol 110 ◽  
pp. 208-214 ◽  
Author(s):  
Di Yun ◽  
Kun Mo ◽  
Walid Mohamed ◽  
Bei Ye ◽  
Marquis A. Kirk ◽  
...  
Keyword(s):  
Fast Reactor ◽  
Temperature Regime ◽  
In Situ Tem ◽  
Thin Specimen ◽  
Reactor Temperature

Specimen heating stage with in-situ evaporator in UHV-STEM for the observation and characterization of monolayered superstructures

1983 ◽  
Vol 41 ◽  
pp. 308-309
Author(s):  
M. Ohtsuki ◽  
J.J. Schuler ◽  
A.V. Crewe ◽  
T. Ichinokawa
Keyword(s):  
Heavy Atom ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Solid Surfaces ◽  
Thin Specimen ◽  
Heating Stage ◽  
Specimen Holder ◽  
Better Than

In-situ evaporating experiments on solid surfaces become meaningful only when the evaporation takes place after the surface of the object is fully cleaned in ultra high vacuum (UHV). A specimen heating stage is usually used for the cleaning process.For the observation of single heavy atom superstructures at atomic resolution in UHV, we have constructed a new specimen heating stage equipped with an insitu evaporator. The device is built into the specimen ante-chamber of the high-resolution UHV-STEM as shown in Figures 1 and 2. The vacuum of the chamber has been tested at 4 × 10-10 torr. with two 20 ℓ/ sec ion pumps attached close to the chamber. The vacuum of the STEM column is better than 1 × 10-10 torr. The heating stage is built into the specimen holder so that direct heating of the specimen is possible. In the detail shown in Figure 2, a thin specimen is mounted between two supporting grids which are then fastened together by two semi-circular tantalum clips. These clips are also used as contacts which carry the current to heat the specimen directly.

In situ synthesis of CO2 adducts of modified polyethylenimines in polyether polyols for polyurethane foaming

2021 ◽  
pp. 0021955X2098715
Author(s):  
Shuai Yuan ◽  
Yuanzhu Long ◽  
Xingyi Xie
Keyword(s):  
Propylene Glycol ◽  
Monomethyl Ether ◽  
Universal Method ◽  
Molecular Weights ◽  
Blowing Agents ◽  
Hydrophobically Modified ◽  
The Matrix ◽  
Poly Propylene ◽  
Polyurethane Foaming

CO2 adducts from hydrophobically-modified polyethylenimines (PEIs) in powder form are newly-developed environment-friendly blowing agents for polyurethanes (PUs). However, they are difficult to disperse into foaming systems that usually contain polyether polyols as the PU soft segments. Herein, we employ mixtures of di(propylene glycol) monomethyl ether-grafted polyethylenimines (DPG-PEIs) and poly(propylene glycol) (PPG) polyols to absorb CO2, with in situ formation of the CO2 adduct particles as PU blowing agents. Their CO2 saturation degrees, revealed by thermogravimetry, scatter in the range of 93–98%. The DPG side chains tend to be exposed at the particle–matrix interface to stabilize the particles. In addition, some PPG oligomers in the matrix might entangle with the CO2 adduct macromolecules during the in situ particle formation. The entangled PPG chains could further stabilize the suspending particles. The high grafting rate and high molecular weight of the PEI backbones could result in small particles, which largely thicken the foaming systems. The optimized blowing agents, with grafting rates between 5% and 8% and PEI backbone molecular weights not higher than 10k Da, show particle sizes from several hundreds of nanometers to ∼1 μm. The resultant foams demonstrate densities below 50 kg/m3 and compressive strengths over 200 kPa, comparable to the values from industrial foams. This in situ CO2 adduction has potential as a universal method suitable for PU foaming at an industrial scale.

Rendez vous with Saturn's rings

1984 ◽  
Vol 75 ◽  
pp. 743-759 ◽  
Author(s):  
Kerry T. Nock
Keyword(s):  
Solar Energy ◽  
Electric Propulsion ◽  
Power Source ◽  
Propulsion System ◽  
Low Thrust ◽  
Ring Plane ◽  
The Earth ◽  
Total Impulse ◽  
Saturn's Rings

ABSTRACTA mission to rendezvous with the rings of Saturn is studied with regard to science rationale and instrumentation and engineering feasibility and design. Future detailedin situexploration of the rings of Saturn will require spacecraft systems with enormous propulsive capability. NASA is currently studying the critical technologies for just such a system, called Nuclear Electric Propulsion (NEP). Electric propulsion is the only technology which can effectively provide the required total impulse for this demanding mission. Furthermore, the power source must be nuclear because the solar energy reaching Saturn is only 1% of that at the Earth. An important aspect of this mission is the ability of the low thrust propulsion system to continuously boost the spacecraft above the ring plane as it spirals in toward Saturn, thus enabling scientific measurements of ring particles from only a few kilometers.

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