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Crude Oils and their Fate in the Environment
Published in Ozcan Konur, Petrodiesel Fuels, 2021
Bryan M. Hedgpeth, Kelly M. McFarlin, Roger C. Prince
The most abundant branched alkanes, iso-alkanes, are pristane and phytane (Figure 43.3), derived from the phytol of chlorophyll during maturation of kerogen under aerobic and anaerobic conditions respectively (Tissot and Welte, 1984). The branching lowers the boiling point of the alkane, so the pristane (C19H40) elutes just after the C17H36n-heptadecane, and phytane (C20H42) just after the C18H38n-octadecane in gas chromatography. As we shall see below, since microbes preferentially consume the linear alkane before the branched form, changes in the ratio of the linear to the branched compound provides an early indication that biodegradation has begun. Collectively, the total abundance of iso-alkanes is usually greater than that of the n-alkanes, but the vast number of isomers dilute the presence of individual compounds and obstruct their specific identification with most analytical methods.
Multiphase nanodispersed systems based on crazed polymers
Published in A. L. Volynskii, N. F. Bakeev, Surface Phenomena in the Structural and Mechanical Behaviour of Solid Polymers, 2018
Figure 8.1 shows the typical calorimetric curves of crystallisation of the saturated hydrocarbon n-octadecane (OD) included in the porous structure of the polyethylene terephthalate and tested in the free state. It may be seen (Fig. 8.1, curve a) that in the free state the hydrocarbon crystallises at 24°C, which is reflected in the form of a non-symmetric exothermic peak. Evidently, the latter circumstance is determined by the transition in the melting range from the rhombic to hexagonal packing, typical of the saturated hydrocarbons [5]. At the same time, the OD, situated in the polymer matrix, shows some previously unknown special features in the thermophysical properties
Asphalt Chemistry: An NMR Investigation of the Benzylic Hydrogens and Oxidation
Published in Arthur M. Usmani, Asphalt Science and Technology, 1997
R. W. Jennings, Jacqueline Fonnesbeck, Jennifer Smith, J.A.S. Pribanic
The effects of model compound dopants on the glass transitions of asphalts AAF- 1, AAG-Ĭ, and AAM-1 were measured. Dopants were selected on the basis of molecular size, functional groups, and conformation (linear or branched). Linear hydrocarbon dopants included octadecane (n-C18H38), tetracosane (π-C24Hĵ0), and hexacontane (/i-C60H122). Branched hydrocarbon dopants included pristane
Preparation and characterization of magnetized GO nanoparticle enhanced microencapsulated phase change material for thermal energy storage application
Published in Indian Chemical Engineer, 2022
V Aiswarya, Sudev Das, Satish Kumar, Aparesh Datta
The phase change properties of MPCM and n-octadecane were studied using DSC, and the findings are shown in Figure 10. Because n-octadecane was encapsulated by MF resin without chemical reaction during the manufacture of CPCM, the phase change behavior of MPCM was identical to that of n-octadecane. The melting point (Tm) and crystallization point (Tc) of n-octadecane MPCM were 32.3 and 17.2 °C. The Tm of the n-octadecane was 14.3 °C lower than the Tm of bulk n-octadecane MPCM without encapsulation, while the Tc of the n-octadecane is higher than the Tc of bulk n-octadecane MPCM. Due to the presence of Ni-GO, more heat is absorbed and released compared to pure n-octadecane so phase change will take more time, as shown in figure 10.
Thermal properties of combat uniforms treated with microencapsulated octadecane and change in clothing microclimate via thermal manikin
Published in The Journal of The Textile Institute, 2018
Eugene Lee, Sangji Han, Kyung-hyun Lee, Jeongmun Lee, Gilsoo Cho
In this study, among hundreds of different PCMs provided from NASA (National Aeronautics and Space Administration) (Hale, Hoover, & ONeill, 1971). Phase change materials handbook.), octadecane of the paraffin series was chosen. Because the material, octadecane, is non-toxic and stable at room temperature, it is being applied in clothing and textile fields (Choi & Cho, 2011). The combat uniform-treated octadecane can be expected to keep the body of soldiers at a constant temperature, regardless of the surrounding environmental temperature change. Hence, octadecane treatment of military combat uniform can be a practical approach to provide thermal comfort via absorption and release of heat. Colvin and Bryant (1998) developed new protective clothing with PCM-treated fabric that demonstrated excellent performance in hot and cold climates. Endrusick, Santee, Gonzalez, Brennick, and Smith (Endrusick, Santee, Gonzalez, Brennick, & Smith, 2000) studied untreated and PCM-treated linings of military boots. They reported that PCM-treated boots provide increased thermal comfort and protection for feet in a cold climate. Because PCMs have been increasingly applied to clothing, such as skiwear, fire fighter’s suit, and underwear, an attempt to applying PCMs to military combat uniform and a comparison of the thermal comfort via wearing test between the untreated and the treated combat uniform will be meaningful. Lee (2013) has suggested the optimum octadecane treatment conditions for minimizing fabric frictional sound of a military combat uniform fabric with thermostatic function. The suggested optimum octadecane treatment conditions were 15.9% of concentration and 113.6 °C of curing temperature. In addition, the thermal properties from octadecane-treated combat uniform fabrics were examined, and then, predicted the heat storage property (ΔHf) of the optimum treatment condition to be 4.70 J/g, considering the fact that the current combat uniform showed its limits especially in summer. The previous studies (Kim, Lee, & Cho, 2016a, 2016b) have calculated the heat of fusion and heat of crystallization of octadecane-treated fabrics. However, there has been a lack of study of wear trials regarding how octadecane affected thermal comfort. Thus, this study used the optimum treatment conditions suggested in the previous study (Lee, 2013) and based on the prediction model suggested in the previous study, to verify the actual function, the octadecane concentrations were set up to 16% (15.9% was suggested as the optimum condition by Lee, 2013), 8, and 0% (untreated) as a control in this study.