Rheological and Chemical Properties of Bitumen Modified With Crumb Rubber in the Dry Process

Author(s):  
Fayssal Cheriet ◽  
Alan Carter ◽  
Smail Haddadi

This research aims to evaluate the performance of the hot mix asphalt modified with crumb rubber by the dry process by studying the temperature’s influence as well as the impact of the digestion time between bitumen and crumb-rubber. The residual bitumen from the drainage test and the non-modified aged bitumen are then subjected to the dynamic shear rheometer (DSR) tests at different frequencies with different temperatures and to Fourier transform infrared spectroscopy (FTIR) analysis. The results show the bitumen and the rubber interaction is directly related to the temperature and the contact time. The maximum increase in rubber mass observed here is about 42% at 195ºC for 120 minutes of contact. The decrease of the light fractions in the bitumen causes a stiffening of the latter as DSR tests show. Lastly, FTIR analysis indicates only a physical interaction.

1934 ◽  
Vol 30 (2) ◽  
pp. 216-224
Author(s):  
P. C. Ho

Owing to its physical and chemical properties being greatly different from those of any of the liquids which have hitherto been used in the Wilson cloud chamber, mercury has been used in the experiments described in this paper and the condensation phenomena of its vapour at different temperatures observed. Before constructing the apparatus it was considered necessary to get from theoretical considerations some idea about the magnitude of the critical supersaturation for mercury vapour in equilibrium with a drop carrying unit charge. Assuming that J. J. Thomson's formula.where s is the supersaturation of mercury vapour in equilibrium with a drop of mercury of radius a, charge e, density σ and surface tension T, the value of which is assumed here to be independent of the radius of the drop, K the specific inductive capacity of the dielectric surrounding the drop, and R the gas constant for one gramme of weight, all at temperature θ, can be applied to the present problem, this critical supersaturation sm is given by the formula


Galaxies ◽  
2022 ◽  
Vol 10 (1) ◽  
pp. 11
Author(s):  
Christian Henkel ◽  
Leslie K. Hunt ◽  
Yuri I. Izotov

Dwarf galaxies are by far the most numerous galaxies in the Universe, showing properties that are quite different from those of their larger and more luminous cousins. This review focuses on the physical and chemical properties of the interstellar medium of those dwarfs that are known to host significant amounts of gas and dust. The neutral and ionized gas components and the impact of the dust will be discussed, as well as first indications for the existence of active nuclei in these sources. Cosmological implications are also addressed, considering the primordial helium abundance and the similarity of local Green Pea galaxies with young, sometimes protogalactic sources in the early Universe.


Environments ◽  
2018 ◽  
Vol 5 (9) ◽  
pp. 104 ◽  
Author(s):  
Elizabeth Pillar-Little ◽  
Marcelo Guzman

Due to the adverse effect of atmospheric aerosols on public health and their ability to affect climate, extensive research has been undertaken in recent decades to understand their sources and sinks, as well as to study their physical and chemical properties. Atmospheric aerosols are important players in the Earth’s radiative budget, affecting incoming and outgoing solar radiation through absorption and scattering by direct and indirect means. While the cooling properties of pure inorganic aerosols are relatively well understood, the impact of organic aerosols on the radiative budget is unclear. Additionally, organic aerosols are transformed through chemical reactions during atmospheric transport. The resulting complex mixture of organic aerosol has variable physical and chemical properties that contribute further to the uncertainty of these species modifying the radiative budget. Correlations between oxidative processing and increased absorptivity, hygroscopicity, and cloud condensation nuclei activity have been observed, but the mechanisms behind these phenomena have remained unexplored. Herein, we review environmentally relevant heterogeneous mechanisms occurring on interfaces that contribute to the processing of aerosols. Recent laboratory studies exploring processes at the aerosol–air interface are highlighted as capable of generating the complexity observed in the environment. Furthermore, a variety of laboratory methods developed specifically to study these processes under environmentally relevant conditions are introduced. Remarkably, the heterogeneous mechanisms presented might neither be feasible in the gas phase nor in the bulk particle phase of aerosols at the fast rates enabled on interfaces. In conclusion, these surface mechanisms are important to better understand how organic aerosols are transformed in the atmosphere affecting the environment.


2020 ◽  
Vol 314 ◽  
pp. 113589 ◽  
Author(s):  
S. Belica-Pacha ◽  
K. Miłowska ◽  
M. Ionov ◽  
M. Bryszewska ◽  
A. Buczkowski ◽  
...  

1996 ◽  
Vol 441 ◽  
Author(s):  
J. Marien ◽  
T. Wagner ◽  
M. Rühle

AbstractThin Nb films were grown by MBE in a UHV chamber at two different temperatures (50°C and 950°C) on the (110) surface of TiO2 (rutile).At a growth temperature of 50°C, reflection high energy electron diffraction (RHEED) revealed epitaxial growth of Nb on rutile: (110)[001] TiO2 ¦¦ (100)[001] Nb. In addition, investigations with Auger electron spectroscopy (AES) revealed that a chemical reaction took place between the Nb overlayer and the TiO2 substrate at the initial growth stage. A 2 nm thick reaction layer at the Nb/TiO2 interface has been identified by means of conventional transmission electron microscopy (CTEM) and high-resolution transmission electron microscopy (HRTEM).At a substrate temperature of 950°C, during growth, the Nb film was oxidized completely, and NbO2 grew epitaxially on TiO2. The structure and the chemical composition of the overlayers have been investigated by RHEED, AES, CTEM and HRTEM. Furthermore, it was determined that the reaction of Nb with TiO2 is governed by the defect structure of the TiO2 and the relative oxygen affinities of Nb and TiO2.


Metals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1297 ◽  
Author(s):  
Cristian Gómez-Rodríguez ◽  
Daniel Fernández-González ◽  
Linda Viviana García-Quiñonez ◽  
Guadalupe Alan Castillo-Rodríguez ◽  
Josué Amilcar Aguilar-Martínez ◽  
...  

The chemical environment and the internal conditions of the furnaces and ladles are extremely aggressive for the refractories, so metallurgical industries demand refractory linings with greater durability and resistance to avoid unforeseen stoppages and to reduce the changes of the furnace lining. Therefore, the current work aims to evaluate the impact of the additions of ZrO2-nanoparticles (1, 3, and 5 wt. %) in magnesia-based bricks. A comparative study of the physical and chemical properties in bricks obtained using two cold pressing techniques (uniaxial and isostatic pressing) and two sintering temperatures (1550 and 1650 °C) was carried out. The microstructure and crystalline phase characteristics obtained after the heat treatments and the slag corrosion test was studied using scanning electron microscopy/electron dispersive X-ray spectroscopy (SEM/EDX) and X-ray diffraction (XRD). The results reveal that the sample with 5 wt. % of ZrO2 nanoparticles (obtained by cold isostatic pressing and sintering at 1650 °C) has the lowest porosity and greatest resistance to penetration of blast furnace slag.


2018 ◽  
Vol 251 ◽  
pp. 02023
Author(s):  
Feodor Portnov

The paper studies kinetic properties of aerosols formed in thermal degradation of wood. The impact of modifying agents in wood surface layer on the quantitative composition of smoke aerosol solids was analyzed. For this purpose, grain-size of aerosol solids was analyzed, and the physical and chemical properties of source and modified wood were assessed.


Author(s):  
Juliany Barbosa de Pinho ◽  
Aloisio Bianchini ◽  
Pedro Silvério Xavier Pereira ◽  
Letycia Cunha Nunes ◽  
Rodrigo Fernandes Daros ◽  
...  

From the pyrolysis process, biochar is a carbon rich and recalcitrant organic material with potential for long term carbon sequestration because of its aromatic structure. However, the physical and chemical properties of the biochar vary due to the diversity of raw material and the conditions of production. The present study aimed to evaluate the biochar from the sugarcane bagasse at different temperatures and under two conditions of pyrolysis. The biochar was produced at two final temperatures 200°C (1 hour); 250°C (1h) and 250°C (2h), with pyrolysis of an oxidizing and non-oxidizing atmosphere for both. PH, cation exchange capacity (CTC), carbon content (C), Nitrogen (N), hydrogen (H), H:C, C:N and ash ratios were evaluated. The contents of C, H, N and the atomic ratios H:C and C:N were higher in Biochar produced in a non-oxidizing atmosphere (BNO). However, the content of ash, pH and CTC were higher in Biochar produced in oxidizing atmospheres (BO). One can conclude the direct influence of the pyrolysis condition.


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