Experiments on the Causes of the Deterioration of Ebonite when Exposed to Light and Air

1930 ◽  
Vol 3 (4) ◽  
pp. 618-625
Author(s):  
D. M. Webster ◽  
B. D. Porritt
Keyword(s):  
Heat Treatment ◽  
Hydrogen Sulfide ◽  
Experimental Error ◽  
Surface Film ◽  
Rate Of Evolution ◽  
Long Period ◽  
Volatile Organic ◽  
Oxidation Of Hydrogen ◽  
Increasing Temperature ◽  
Free Sulfur

Abstract (1) The surface film of a sample of ebonite—containing no “free” sulfur—has been shown to develop distinct traces of sulfurous and sulfuric acid after exposure to light in a moist atmosphere for a period of four weeks. (2) The above acids appear to result from the oxidation of hydrogen sulfide formed through the decomposition of the hydrocarbon-sulfur nucleus of the ebonite. (3) The rate of evolution of hydrogen sulfide from ebonite when heated in an atmosphere of hydrogen has been investigated for temperatures ranging from 180° to 250° C., and for three different samples of ebonite. (4) For a given temperature the rate of evolution is rapid at first, but falls off quickly and finally remains uniform over a long period, the latter portion of the time-H2S curve being linear within the limits of experimental error. (5) The rate of evolution increases with increasing temperature. (6) Under the heat treatment the ebonite changes in color, becoming reddish in appearance. At the same time it becomes unsaturated and more and more soluble in acetone and carbon disulfide. (7) The decomposition which takes place on heating ebonite to temperatures not exceeding 250° C. does not appear to give rise to appreciable amounts of either free sulfur or volatile organic compounds. (8) The bearing of the above results on the problem of the electrical deterioration of ebonite has been discussed.

Novel aqueous chelating agents for catalytic oxidation of hydrogen sulfide to sulfur by air

2005 ◽  
Vol 4 (2) ◽  
pp. 157-175 ◽  
Author(s):  
Guoxiong Hua ◽  
Qingzhi Zhang ◽  
Derek McManus ◽  
Alex M. Z. Slawin ◽  
J. Derek Woollins
Keyword(s):  
Hydrogen Sulfide ◽  
Catalytic Oxidation ◽  
Chelating Agents ◽  
Oxidation Of Hydrogen

Study the Effect of Heat Treatment and Pressure on some the Optical Properties of the Pure PVA Nano Polymer

2021 ◽  
Vol 900 ◽  
pp. 16-25
Author(s):  
Tabarak Mohammed Awad ◽  
May A.S. Mohammed
Keyword(s):  
Heat Treatment ◽  
Dielectric Constant ◽  
Refractive Index ◽  
Optical Properties ◽  
Absorption Coefficient ◽  
Polyvinyl Alcohol ◽  
Complex Dielectric Constant ◽  
Different Temperatures ◽  
German Origin ◽  
Increasing Temperature

In this study, some optical properties were studied of the pure vinyl polyvinyl alcohol (PVA) nanopolymer (German origin). Under the influence of different temperatures and pressures of PVA. Where 25 samples were prepared for the purpose of conducting the research. Which studied the study of these samples was done by recording the absorbance and transmittance spectra of the wavelengths (200-900) nm. From them, absorbance, transmittance, reflectivity, absorption coefficient, refractive index, extinction coefficient, complex dielectric constant were calculated. At different temperatures (25,40, 80, 120, 160)°C. And with different pressures within the range (7.5,8,8.5,9,9.5) MPa. The results are that the permeability of the polymer (PVA) at different temperatures for each pressure decreases with increasing temperature, and that all other calculated optical properties increase with increasing temperature.

Morphological basis for the complex melting behaviour of isotactic polystyrene

e-Polymers ◽  
2002 ◽  
Vol 2 (1) ◽  
Author(s):  
Mahmoud Al-Hussein ◽  
Gert Strobl
Keyword(s):  
Morphological Changes ◽  
Melting Behaviour ◽  
Temperature Dependent ◽  
Molten Material ◽  
Scanning Calorimetry ◽  
Isotactic Polystyrene ◽  
X Ray ◽  
Long Period ◽  
X Ray Scattering ◽  
Increasing Temperature

AbstractTemperature-dependent small-angle X-ray scattering spectroscopy of isothermally cold crystallized isotactic polystyrene revealed considerable morphological reorganization during subsequent heating to the melt. Both the crystalline thickness and the long period increased continuously with increasing temperature before the samples finally melted. The temperature dependence of these changes correlated very well with the melting behaviour observed with differential scanning calorimetry. As the temperature increased during a heating scan, the initial lamellae that formed during isothermal crystallization showed only little reorganization until they started to melt. Then, the molten material recrystallized continuously into increasingly thicker lamellae at increasing temperature until they finally melted. As the crystallization temperature approached the final melting temperature of the recrystallized lamellae, the initial lamellae melted without further recrystallization and no morphological changes were seen in this case.

scholarly journals EFFECT OF CHEMICAL AND THERMAL TREATMENTS ON INHIBITION OF PEROXIDASE ACTIVITIE OF PURPLE SKIN EGGPLANT (SOLANUMMELONGENA L.)

2021 ◽  
Vol 9 (04) ◽  
pp. 304-313
Author(s):  
Jocelyn Constant Yapi ◽  
◽  
Jean Bedel Fagbohoun ◽  
Zranseu Ange Benedicte Deffan ◽  
Elvis Gbocho Serge Ekissi ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Thermal Inactivation ◽  
Solanum Melongena ◽  
Thermal Treatments ◽  
Optimal Temperature ◽  
Spectrophotometric Methods ◽  
Acid Effect ◽  
Fresh Cut ◽  
D Values ◽  
Increasing Temperature

Peroxidase (POD) associated with the browning of fresh-cut fruits and vegetableswas extracted from purple skin eggplant(Solanum melongena L.) and characterised using reliable spectrophotometric methods. Maximal POD activity was found at 35 °C and pH 6.0 with guaiacol as the substrate. The enzyme was stable at his optimal temperature (35 °C) and hisat pH stability was in the range of 5.6 - 6.6.Peroxidase retained its full activity in the presence of ion K+, Cu2+, Na+, Pb2+ and Ba2+ but were inhibited strongly by the ion Fe2+ and Mg2+ and the reducing agents as sodium thiosulfateand ascorbic acid. Effect of heattreatment on eggplant peroxidase showed that D-values decreased with increasing temperature, indicating faster peroxidase inactivation at higher temperatures.At 60 °C, the D-values ranged from 20.42 to 54.24 min. Hence, heat treatment at 60 °C for 30 min reduced browning of eggplant fruit.These data can be used to predict prevention of browning in the purple skin eggplantby thermal inactivation and the use of chimical agents onthe enzyme.

scholarly journals Oxidation of Hydrogen Sulfide with Cell-free Extract of Hyphomicrobium neptunium ATCC 15444

1992 ◽  
Vol 112 (5) ◽  
pp. 332-335
Author(s):  
Takashi SASAHIRA ◽  
Katsuhiko MATSUI ◽  
Toshihiko ARAI
Keyword(s):  
Hydrogen Sulfide ◽  
Cell Free Extract ◽  
Oxidation Of Hydrogen

scholarly journals Selective Oxidation of Hydrogen Sulfide Containing Ammonia and Water Using Fe2O3/SiO2Catalyst

2012 ◽  
Vol 50 (3) ◽  
pp. 398-402
Author(s):  
Moon-Il Kim ◽  
Gu-Hwa Lee ◽  
Sung-Woo Chun ◽  
Dae-Won Park
Keyword(s):  
Hydrogen Sulfide ◽  
Selective Oxidation ◽  
Oxidation Of Hydrogen
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