Oxidation of Compounds Structurally Related to GR-S

1950 ◽  
Vol 23 (4) ◽  
pp. 836-846 ◽  
Author(s):  
J. W. Lawrence ◽  
J. Reid Shelton
Keyword(s):  
Carbon Dioxide ◽  
Oxygen Absorption ◽  
Phenyl Radical ◽  
Rate Data ◽  
Primary Products ◽  
Period 2 ◽  
Constant Rate ◽  
Three Stages ◽  
Oxidized Products ◽  
Short Induction Period

Abstract The rates of oxidation of 1-phenyl-3-pentene, 1-phenyl-4-hexene, and 1-phenyl-3-vinylbutane have been measured at 100° C and 1 atmosphere of oxygen pressure. 1-Phenyl-2-butene has also been included to complete the sequence 1–4, 1–3, and 1–2 with respect to the structural relationship between the phenyl radical and the point of unsaturation. Information concerning the course of the reaction was obtained both from the rate data and from chemical analysis of the oxidized products. Three stages of oxidation were noted: (1) a very short induction period; (2) an autocatalytic stage which is characterized by a rapidly increasing rate and in which the primary products appear to be peroxides; and (3) a period characterized by a constant rate of oxygen absorption with the formation of such products as acids, esters, carbon dioxide, and water.

Oxidation of GR-S Vulcanizates

1946 ◽  
Vol 19 (3) ◽  
pp. 696-711
Author(s):  
J. Reid Shelton ◽  
Hugh Winn
Keyword(s):  
General Nature ◽  
Oxygen Absorption ◽  
Specimen Thickness ◽  
Absorption Data ◽  
First Order ◽  
Rapid Absorption ◽  
Constant Rate ◽  
Absorption Studies ◽  
Three Stages ◽  
Useful Life

Abstract Oxygen absorption studies on a tread type GR-S vulcanizate show: 1. There are three stages involved in the oxidation: (1) an initial rapid absorption, of apparent first order at constant pressure, which is of short duration and appears to involve a limited number of especially reactive centers in the vulcanizate ; (2) a constant-rate reaction, of apparent zero order at constant oxygen pressure, which would extend over most of the useful life of the vulcanizate in service ; (3) an autocatalytic reaction, beginning after a given stock has absorbed a definite amount of oxygen that is independent of the temperature at which the absorption takes place. 2. The rate of oxygen absorption increases with temperature. The temperature coefficient for the constant rate reaction is 2.6 for a 10° C change in temperature over the range 80° to 120° C. 3. Diffusion is not rate controlling, provided the specimen thickness does not exceed 0.080 inch at 100° C or 0.040 inch at 120° C. 4. The effect of cure on the rate of oxygen absorption by GR-S vulcanizates is slight, and consequently, the technique is particularly useful for studying the effect of changes in compounding upon aging resistance. 5. Oxygen absorption data can be satisfactorily correlated with changes in physical properties during aging. While the fundamental nature of the mechanism of the oxidation of GR-S is still unknown, considerable information has been obtained with respect to some of the factors involved, and the general nature of the reaction has been established. This information, together with the work still in progress, should be of value in pointing the way toward possible methods of improving the resistance of GR-S to aging.

The effect of a ketamine constant rate infusion on cardiovascular variables in sheep anesthetized at the minimum alveolar concentration of sevoflurane that blunts adrenergic responses

2022 ◽  
pp. 1-7
Author(s):  
Kevin Chang ◽  
Michele Barletta ◽  
Kristen M. Messenger ◽  
Daniel M. Sakai ◽  
Rachel A. Reed ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Minimum Alveolar Concentration ◽  
Plasma Concentrations ◽  
Face Mask ◽  
Constant Rate Infusion ◽  
Carbon Dioxide Rebreathing ◽  
Constant Rate ◽  
Significant Difference ◽  
Treatment Administration ◽  
Rate Infusion

Abstract OBJECTIVE To evaluate the effect of a constant rate infusion of ketamine on cardiac index (CI) in sheep, as estimated using noninvasive cardiac output (NICO) monitoring by partial carbon dioxide rebreathing, when anesthetized with sevoflurane at the previously determined minimum alveolar concentration that blunts adrenergic responses (MACBAR). ANIMALS 12 healthy Dorset-crossbred adult sheep. PROCEDURES Sheep were anesthetized 2 times in a balanced placebo-controlled crossover design. Anesthesia was induced with sevoflurane delivered via a tight-fitting face mask and maintained at MACBAR. Following induction, sheep received either ketamine (1.5 mg/kg IV, followed by a constant rate infusion of 1.5 mg/kg/h) or an equivalent volume of saline (0.9% NaCl) solution (placebo). After an 8-day washout period, each sheep received the alternate treatment. NICO measurements were performed in triplicate 20 minutes after treatment administration and were converted to CI. Blood samples were collected prior to the start of NICO measurements for analysis of ketamine plasma concentrations. The paired t test was used to compare CI values between groups and the ketamine plasma concentrations with those achieved during the previous study. RESULTS Mean ± SD CI of the ketamine and placebo treatments were 2.69 ± 0.65 and 2.57 ± 0.53 L/min/m2, respectively. No significant difference was found between the 2 treatments. Mean ketamine plasma concentration achieved prior to the NICO measurement was 1.37 ± 0.58 µg/mL, with no significant difference observed between the current and prior study. CLINICAL RELEVANCE Ketamine, at the dose administered, did not significantly increase the CI in sheep when determined by partial carbon dioxide rebreathing.

STUDIES OF THE TOMATO IN RELATION TO ITS STORAGE: II. THE EFFECTS OF ALTERED INTERNAL ATMOSPHERE UPON THE RESPIRATORY AND RIPENING BEHAVIOUR OF TOMATO FRUITS STORED AT 12.5 °C.

1941 ◽  
Vol 19c (12) ◽  
pp. 500-518 ◽  
Author(s):  
K. A. Clendenning
Keyword(s):  
Carbon Dioxide ◽  
Tomato Fruit ◽  
Colour Change ◽  
Tomato Fruits ◽  
Carbon Dioxide Output ◽  
Constant Rate ◽  
Yellow Orange ◽  
Softening Process ◽  
Green Stage ◽  
Second Peak

When a mature green tomato fruit is stored at 12.5 °C. either with or without its stem, the expected respiratory climacteric accompanies the colour change associated with ripening. When the stem is removed and the stem scar area is covered carefully with hot paraffin wax, the fruit thereafter ripens slowly with a low, relatively constant rate of carbon dioxide output. These characteristics are ascribed to "auto-gas" storage resulting from restricted diffusion at the stem scar. The effect of waxing is reversible within limits since removal of the artificial seal after one month has resulted in a return to normal ripening and respiratory behaviour.When yellowing, yellow orange, and full red fruits are stored either with or without their stems, they complete in storage those phases of the respiratory climacteric that had not been completed before detachment from the plant. The careful waxing of fruits picked at these stages of maturity inhibits further coloration and reduces the rate of carbon dioxide output to the same extent as in fruits waxed at the mature green stage. The respiratory drift of fruits picked and stored unwaxed at the early "growing green" stage is characterized by two distinct peaks. Such fruits eventually ripen and the second peak is associated with the colour change that accompanies ripening. Similar fruits stored with stem scars waxed fail to ripen before their pathological "death" and their respiration rate is reduced by the waxing treatment.When yellowing and yellow-orange fruits are waxed, they become soft and highly susceptible to fungal attack before their ripening coloration has been completed. To inhibit the softening process in stored tomatoes, it thus appears to be necessary to apply wax before ripening has commenced. Unwaxed fruits become highly susceptible to fungal wastage only after attaining full ripeness. Waxed fruits on the other hand are subject to fungal wastage when green or partially coloured as well as when fully ripened. This is attributed to the progress of softening in the absence of the usual colour change associated with ripening. Waxing of the stem scars does not act as a deterrent to storage moulds at the waxed area. The waxed tomato has been found to be subject to several physiological disorders the symptoms of which are described.

Equilibrium and Rate Data for the Extraction of Lipids Using Compressed Carbon Dioxide

1987 ◽  
Vol 22 (2-3) ◽  
pp. 1103-1120 ◽  
Author(s):  
M. B. King ◽  
T. R. Bott ◽  
M. J. Barr ◽  
R. S. Mahmud ◽  
N. Sanders
Keyword(s):  
Carbon Dioxide ◽  
Rate Data ◽  
Compressed Carbon Dioxide

PENYERAPAN GAS KARBONDIOKSIDA (CO 2 ) DALAM BIOGAS DENGAN LARUTAN Ca(OH)2

EKUILIBIUM ◽  
2015 ◽  
Vol 14 (1) ◽  
Author(s):  
Paryanto Paryanto
Keyword(s):  
Experimental Data ◽  
Carbon Dioxide ◽  
Order Reaction ◽  
First Order Reaction ◽  
Glass Ball ◽  
Carbon Dioxide Content ◽  
First Order ◽  
Constant Rate ◽  
Rate Of Reaction ◽  
Reduce Carbon Dioxide

<p>Abstract: Carbon dioxide content in biogas produced by fermentation is still high. Because of<br />that, biogas need a process purification to reduce carbon dioxide content. In this work, Ca(OH)2<br />solution was contacted with biogas in a column for reducing the CO<br />2<br />content. This research<br />studied the effect of packing type used in absorber column on the rate of CO<br />2<br />reduction. Based<br />on experimental data and modelling, it was found that the reaction between CO<br />2<br />followed first order reaction. The constant of rate reaction was affected by the packing type<br />which using glass ball, plastic pipe, ceramic, wood, and clay roof, the constant rate were 0.781,<br />0.464, 0.916, 0.637, and 0.987 min<br />Keywords: Biogas, CO<br />2<br />, Ca(OH)2<br />-1<br />, respectively.<br />, absorber, rate of reaction</p>

Rubber Oxidation and Aging Studies Safe Limits of Sample Thickness

1951 ◽  
Vol 24 (4) ◽  
pp. 999-1016
Author(s):  
George W. Blum ◽  
J. Reid Shelton ◽  
Hugh Winn
Keyword(s):  
Natural Rubber ◽  
Accelerated Aging ◽  
Sample Thickness ◽  
Oxygen Absorption ◽  
Absorption Data ◽  
Synthetic Rubber ◽  
Constant Rate ◽  
Aging Studies ◽  
Safe Limits ◽  
Natural Rubber Vulcanizates

Abstract Safe limits of sample thickness for rubber oxidation and aging studies, such that the chemical reaction rather than the rate of diffusion will be rate-controlling have been investigated for natural-rubber vulcanizates and for four synthetic-rubber types. For studies involving the entire range of oxidation, including the autocatalytic stage of rapid oxygen absorption, the conventional 0.075-inch thickness is frequently not satisfactory for accelerated aging and oxidation studies if it is desired to avoid limitation by diffusion. Only in the GR-S black stock was this thickness found to be satisfactory up to a temperature of 100° C. The other stocks, including natural rubber, Butaprene-NXM, and Neoprene black and gum stocks all require thinner samples to ensure that the observed rate of oxygen absorption is free of limitation by diffusion. A method of calculating the probable limiting value of sample thickness, above which the rate of oxidation in the autocatalytic stage is limited by diffusion, has been developed on the basis of volumetric oxygen absorption data obtained with GR-S. The method has also been applied to natural-rubber vulcanizates and to other synthetic-rubber types to locate the approximate limiting values at various temperatures for oxidation and aging studies which extend into the autocatalytic stage of rapid reaction. The constant-rate period of oxidation is more important from a practical point of view than the autocatalytic stage, since properties are so seriously degraded as to make the rubber of little value before it reaches the final stage of rapid oxidation. Somewhat thicker samples may be used for studies that are confined to the earlier stages of oxidation. A 0.075-inch sample is free of limitation by diffusion in the constant-rate stage in the following cases: GR-S black and gum stocks at 110° C; Hevea black with added antioxidant at 100° C; and uninhibited Hevea black and gum stocks at 60° C. A 0.040-inch sample is satisfactory in this range for: uninhibited Hevea black at 100° and gum at 80° C; Butaprene-NXM black at 100° and gum at 90° C; and Neoprene black and gum stocks at 100° C.

Manufacturing Technique and Property Evaluations of Protective Textiles

2013 ◽  
Vol 457-458 ◽  
pp. 375-378
Author(s):  
Ching Wen Lou ◽  
Ting Ting Li ◽  
Mei Chen Lin ◽  
Jan Yi Lin ◽  
Jia Horng Lin
Keyword(s):  
Carbon Dioxide ◽  
Impact Strength ◽  
Carbon Dioxide Emission ◽  
High Strength ◽  
Puncture Resistance ◽  
Carbon Reduction ◽  
Nonwoven Fabrics ◽  
Constant Rate ◽  
The Difference ◽  
Protective Textiles

Global warming increases each day and causes people to pay more attention to the reduction of carbon dioxide emission in order to mitigate the increase in temperature. Reducing, reusing, and recycling can effectively reduce the emission of carbon dioxide, to attain goals of energy conservation and carbon reduction. This study aims to explore the difference in the punch resistance and impact strength between the polyethylene terephthalate (PET) nonwoven fabrics and PET/TPU honeycomb grid/PET (P/T/P) composites. Recycle PET, high strength PET, and low melting PET are made into PET nonwoven fabrics, two layers of which are laminated with a TPU honeycomb grid, the interlayer, to form P/T/P composites. The constant rate puncture resistance, dynamic puncture resistance, and impact strength of PET nonwoven fabrics and P/T/P composites are evaluated. The experiment results show that both the constant rate and dynamic puncture resistances of P/T/P composites are lower than those of PET nonwoven fabrics.

The Reaction of Ozone with SBR Rubbers

1959 ◽  
Vol 32 (4) ◽  
pp. 1062-1079 ◽  
Author(s):  
E. R. Erickson ◽  
R. A. Berntsen ◽  
E. L. Hill ◽  
Paul Kusy
Keyword(s):  
Initial Rate ◽  
Protective Action ◽  
Rate Data ◽  
High Solubility ◽  
Initial Concentration ◽  
Degree Of Protection ◽  
Effective Barrier ◽  
Gaseous Ozone ◽  
Low Concentrations ◽  
Oxidized Products

Abstract All SBR vulcanizates, when tested in a relaxed state, reacted with ozone of low concentrations to form a film of oxidized products which provided an effective barrier against further attack by gaseous ozone. SBR vulcanizates that were under stress, but which contained no effective antiozonant in their formulation, were readily attacked by ozone. The absorption of ozone appeared to begin with an initial rate of zero which was followed by rapidly increasing rates until a maximum had been reached, when ozone cracks were visible on the surface of the rubber. SBR vulcanizates that were under stress, but which contained an antiozonant, were protected from an attack by ozone to a degree that ranged from poor to excellent. The degree of protection depended (a) on the differential in the rates of reaction of the antiozonant and the rubber hydrocarbon with ozone, (b) on the initial concentration of the antiozonant on the surface of the vulcanizate which reacted with ozone to form a barrier of oxidized residues, and (c) on the rate of effusion of fresh antiozonant from within the rubber to the outer surface of the barrier. SBR vulcanizates containing a naphthenic processing oil as an extender were not so resistant to ozone as standard SBR vulcanizates. It is probable that the effectiveness of the antiozonants tested in these vulcanizates was reduced by their high solubility in the oil phase. SBR vulcanizates containing trioctyl phosphate as a plasticizer were vigorously attacked by ozone. It is possible that the gaseous ozone dissolved to some extent into the plasticizer phase, increasing the concentration of ozone in the area causing a more severe oxidation of the rubber. SBR vulcanizates that had been coated with an antiozonant by dipping the specimen several times into a solution of the antiozonant in a solvent were found to contain a higher concentration of the antioxonant directly on the surface of the vulcanizate than in the case where three parts of the antiozonant were added during vulcanization. A mechanism for the ozonization of SBR vulcanizates has been proposed which includes a possible mechanism for the protective action of antiozonants. A rate equation has been derived from this mechanism which was consistent with the experimental rate data.

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