Behaviour of a common phthalate plasticizer (dioctyl phthalate) during the alkali- and/or acid-catalysed steps in an AOCS method for the preparation of methyl esters

1991 ◽  
Vol 587 (2) ◽  
pp. 263-267 ◽  
Author(s):  
N.C. Shantha ◽  
R.G. Ackman
Polymers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 2809
Author(s):  
Gergely Márk Csányi ◽  
Semih Bal ◽  
Zoltán Ádám Tamus

The effect of short-term (3- and 6-h-long) periodic thermal aging was investigated at three different temperatures on PVC cables and PVC films. Three different temperatures (110, 125, and 140 °C) were used for aging PVC cables and one (110 °C) for PVC films. PVC films were prepared for the investigation containing 0, 30, 40, and 50 weight percent of dioctyl phthalate plasticizer (DOP). The effect of short-term thermal aging was monitored by electrical (dielectric spectrum and voltage response measurement) and mechanical (Shore D hardness) methods. From the loss factor measurements, different deducted quantities were calculated and compared with Shore D hardness, which has been shown to be a parameter reflecting the effect of short-term thermal aging on PVC insulation. The measurements revealed that Shore D hardness is not the best property for monitoring aging. Instead, increasing dissipated power and the shifting behavior of tan δ–frequency curves proved to be the best phenomena for assessing the impact of thermal aging. Simple deducted quantities may provide a basis for following short-term thermal aging.


2018 ◽  
Vol 186 ◽  
pp. 1021-1030 ◽  
Author(s):  
Ting Zheng ◽  
Zhenyu Wu ◽  
Qinglong Xie ◽  
Jiaojiao Fang ◽  
Yunchen Hu ◽  
...  

1971 ◽  
Vol 54 (1) ◽  
pp. 47-51
Author(s):  
Anita Huang ◽  
David Firestone

Abstract A procedure is described for differential infrared spectrophotometric determination of low levels (1–6%) of isolated trans isomers in vegetable oils or derived methyl esters. Triglycerides and methyl esters of known isolated trans content were analyzed by the procedure and results compared with those obtained with the American Oil Chemists’ Society tentative method for isolated trans isomers. Results obtained by the described method are more accurate than those obtained by the AOCS method.


Author(s):  
Peter K. Hepler ◽  
Dale A. Callaham

Calcium ions (Ca) participate in many signal transduction processes, and for that reason it is important to determine where these ions are located within the living cell, and when and to what extent they change their local concentration. Of the different Ca-specific indicators, the fluorescent dyes, developed by Grynkiewicz et al. (1), have proved most efficacious, however, their use on plants has met with several problems (2). First, the dyes as acetoxy-methyl esters are often cleaved by extracellular esterases in the plant cell wall, and thus they do not enter the cell. Second, if the dye crosses the plasma membrane it may continue into non-cytoplasmic membrane compartments. Third, even if cleaved by esterases in the cytoplasm, or introduced as the free acid into the cytoplasmic compartment, the dyes often become quickly sequestered into vacuoles and organelles, or extruded from the cell. Finally, the free acid form of the dye readily complexes with proteins reducing its ability to detect free calcium. All these problems lead to an erroneous measurement of calcium (2).


1966 ◽  
Vol 16 (01/02) ◽  
pp. 018-031 ◽  
Author(s):  
S Sherry ◽  
Norma Alkjaersig ◽  
A. P Fletcher

SummaryComparative studies have been made of the esterase activity of plasmin and the streptokinase-activator of plasminogen on a variety of substituted arginine and lysine esters. Human plasmin preparations derived by different methods of activation (spontaneous in glycerol, trypsin, streptokinase (SK) and urokinase) are similar in their esterase activity; this suggests that the molecular structure required for such esterase activity is similar for all of these human plasmins. Bovine plasmin, on the other hand, differs from human plasmin in its activity on several of the substrates studied (e.g., the methyl esters of benzoyl arginine and tosyl, acetyl and carbobenzoxy lysine), a finding which supports the view that molecular differences exist between the two animal plasmins. The streptokinase-activator hydrolyzes both arginine and lysine esters but the ratios of hydrolytic activity are distinct from those of plasmin and of other activators of plasminogen. The use of benzoyl arginine methyl ester as a substrate for the measurement of the esterase activity of the streptokinase-activator is described.


2019 ◽  
Author(s):  
Chem Int

Biodiesel produced by transesterification process from vegetable oils or animal fats is viewed as a promising renewable energy source. Now a day’s diminishing of petroleum reserves in the ground and increasing environmental pollution prevention and regulations have made searching for renewable oxygenated energy sources from biomasses. Biodiesel is non-toxic, renewable, biodegradable, environmentally benign, energy efficient and diesel substituent fuel used in diesel engine which contributes minimal amount of global warming gases such as CO, CO2, SO2, NOX, unburned hydrocarbons, and particulate matters. The chemical composition of the biodiesel was examined by help of GC-MS and five fatty acid methyl esters such as methyl palmitate, methyl stearate, methyl oleate, methyl linoleate and methyl linoleneate were identified. The variables that affect the amount of biodiesel such as methanol/oil molar ratio, mass weight of catalyst and temperature were studied. In addition to this the physicochemical properties of the biodiesel such as (density, kinematic viscosity, iodine value high heating value, flash point, acidic value, saponification value, carbon residue, peroxide value and ester content) were determined and its corresponding values were 87 Kg/m3, 5.63 Mm2/s, 39.56 g I/100g oil, 42.22 MJ/Kg, 132oC, 0.12 mgKOH/g, 209.72 mgKOH/g, 0.04%wt, 12.63 meq/kg, and 92.67 wt% respectively. The results of the present study showed that all physicochemical properties lie within the ASTM and EN biodiesel standards. Therefore, mango seed oil methyl ester could be used as an alternative to diesel engine.


2019 ◽  
Vol 56 (4) ◽  
pp. 279-286 ◽  
Author(s):  
Tomasz Wasilewski ◽  
Yong-Qiang Sun ◽  
Wiesław Hreczuch ◽  
Artur Seweryn ◽  
Tomasz Bujak

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