原油中石蜡沉积的热力学模型

1 INTRODUCTION Crude oils are mixture of light and heavy hydro-carbons. The components in crude oils can be classi-fied into paraffin, naphthene and aromatic compo-nents[1]. Though the non-n-alkane components in crude oils are minor, it is essential to consider the in-fluence of non-alkane components in the model since their properties, such as fusion temperature and fusion enthalpy, are much different from paraffin. The solu-bility of each component of crude oils depends on the temperatu…     

Zerkleinerung von Wachsen auf Luftstrahlmühlen sowie Verwendung mikronisierter Wachse in Anstrichmitteln

Grinding of Waxes by Air Jet Mills and the Application of Micronized Waxes in Paintings Micronization of crystalline waxes by air jet mills yields products with a main particle size below 5–10 micron. There are no moving parts in the micronizing chamber of the air jet mill. Diminishing of the particles is obtained by collision and friction in the round grinding chamber. By homogeneous distribution of micronized waxes in coating systems special properties like resistance against scratches, dullness, resistance against metal markings can be obtained for dry films of lacquers. The effect of pulverized waxes is used in manifold application areas of lacquers to improve the surface properties.     

Altering Silk Film Surface Properties through Lotus‐Like Mechanisms

The nonwetting and self‐cleaning properties of the lotus depend on microscale and nanoscale roughness provided in part by a covering of epicuticular waxes that crystalize on the surface of its leaves. Wax deposition is driven by the evaporation of water, which carries waxes to the surface as it moves through the epidermis and cuticle. If the wax layer is damaged, repair occurs through the same mechanism. The experiments described herein have exploited this principle to establish a completely biologically derived system based on silk and lotus epicuticular wax, showing that it is possible to coat silk surfaces with waxes and thereby change their wetting characteristics and tensile properties. The robustness of the material is also documented by crystal regrowth after damage to the wax layer through abrasion (scratching and rubbing), resistance to water‐jetting, and UV exposure. To further characterize this system, the diffusion of natural and synthetic waxes through two types of silk films, Bombyx mori fibroin and engineered spider silk are studied, showing that the extent of wax diffusion through silk membranes depends upon wax type and protein structure, which remains unchanged through the process. Making use of the simple passive phenomenon of advection, these studies represent a method of low‐energy fabrication of completely biological, lotus‐inspired membranes with tunable surfaces.     

Der Einfluß von Wachsen auf die Eigenschaften,insbesondere die Scheuerfestigkeit von Druckfarben

The influence of Waxes on the Properties of Printing Inks The influence of waxes on the properties of printing inks and printed materials is shown with the examples of straight chain and differently branched hydrocarbons. The waxes in finely dispersed state are imbedded in the printing inks like pigments and retain this state in the dried printing ink film. Polyethylene waxes change the rheological behaviour of the printing inks and above all improve the scratch and scrubb resistance of the finished prints. On the basis of measurements carried out with printing inks and printed matter it has been tried to explain the mechanism of the action of polyethylene waxes on the printing inks.     

Neuartige emulgierbare Polyäthylenwachse

Novel Emulsifiable Polyethylene Waxes In comparison to naturally occuring waxes and their derivatives, the group of synthetically prepared emulsifiable polyethylene waxes known so far exhibit a relatively small proportion of polar centers in their molecular structure. Using a new process of preparation, products having a high content of hydrophilic groups are obtained. The properties and emulsifying techniques are described. This report also includes the development of a new group of purely non-ionic emulsifiable very hard polymer waxes.     

Wachse für die Zitrusfruchtbeschichtung

Waxes for Citrus Fruit Coating In the last years waxes basing on polyethylen have got a great importance in the field of citrus fruit coating. The propitious physiological and processing properties of these waxes were supposition for this development. Polyethylen wax coatings effect e. g. a reduction of water vapour permeability and lost of weight, an improvement of gloss, influence on respiration and the internal oxygen and carbondioxide content of the fruit.     

Umweltverhalten und Toxikologie der Wachse

Environmental Behaviour and Toxicology of Waxes Plant and animal waxes are chemically relatively stable nontoxic substances and are used by humans since ages. In the nature waxes have protective function against environmental influences. This protective action is possible due to great resistance of the waxes towards environment, which also means low biological degradability. Obviously, waxes are undigestible and non-toxic in human and animal organism. Partially synthesized waxes based on montana wax, a plant fossil wax, have a structure similar to natural waxes, and therefore they resemble natural waxes with regard to environmental behaviour and are fully harmless from toxicological viewpoint. Also fully synthetic waxes, such as polyethylene waxes and polyethylene oxide waxes have, according to results obtained so far, no undesirable effects on environment. Waxes have been approved in foods worldwide, obviously due to their favorable toxicological properties.     

Wachssynthese mittels der Guerbet-Reaktion

Synthesis of Waxes by Guerbet Reaction Branched chain waxes possess better liquifying properties and superior solubility in organic solvents than straight chain waxes. Branched chain waxes having both of the above properties were therefore synthesized by a new principle, namely the Guerbet reaction. Guerbet alcohols, based on technical octadecyl alcohol were esterified with various mono- and dicarboxylic acids. Strongly branched and relatively low melting waxes were thus obtained which, inspite of their greater solubility in organic solvents, exhibit insignificant liquifying effect in wax pastes. As against these, when the Guerbet alcohols from stearyl alcohol are oxidized, branched chain wax alcohols are obtained which in native as well as saponified state show liquifying action on wax pastes. The Guerbet reaction is explained taking the example of a mixture of two primary alcohols.     

Die Emulgierung oxidierter Polyäthylen-Wachse mit ionisch-nichtionischen Emulgator-Systemen

Emulsification of Oxidized Polyethylene Waxes with Ionic-Nonionic Emulsifier Systems The author reports on the emulsification of oxidized polyethylene waxes with varying acid values and molecular weight distributions. The emulsifier system comprised of predominantly a nonionic ethoxylated surfactant based on alkyl phenol in combination with a small amount of alkali hydroxide to which the water for emulsification was added. Emulsion properties, such as viscosity, pH-value, particle size (light transmission), and glaze of the dry films on plane surface, were used to formulate the optimum emulsifier systems. Thus, the optimum ratio of the components and the degree of ethoxylation of the nonionic surfactant were determined. Similarly, the method of emulsifying was optimized and the differences among the various existing polyethylene waxes were determined.     

Thermal and mechanical properties of LDPE/sisal fiber composites compatibilized with functionalized paraffin waxes

The effect of maleic anhydride‐grafted hard paraffin wax (MA‐g‐wax) and oxidized hard paraffin wax (OxWax), as possible compatibilizers, on the morphology, thermal and mechanical properties of LDPE/sisal fiber composites were examined. The differential scanning calorimetry (DSC) results show that sisal alone did not change the crystallization behavior of LDPE, while the two waxes influenced the crystallization behavior of LDPE in different ways, whether mixed with LDPE alone or in the presence of sisal. The thermal properties seem to be influenced by the fact that the waxes preferably crystallize around the short sisal fibers, and by the fact that the two waxes have different compatibilities with LDPE. The TGA results show an increase in the thermal stability of the blends in the presence of the two waxes, with LDPE/OxWax showing a more significant improvement. The presence of wax, however, reduced the thermal stability of the LDPE/sisal/wax composites. The presence of OxWax and MA‐g‐wax similarly influenced the tensile properties of the composites. Both waxes similarly improved the modulus of the compatibilized composites, but in both cases the tensile strengths were worse, probably because of a fairly weak interaction between LDPE and the respective waxes. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Über eine dünnschicht-chromatographische Identifizierung genuiner Naturwachse

Identification of Genuine Natural Waxes by Thin-Layer Chromatography Genuine waxes can be identified distinctly in a reproducible manner by examining certain extracts of these waxes by thin-layer chromatography. Using benzene as mobile phase, the extracts are resolved on Silicagel HF plates into individual components that were not investigated further. Under UV light these components are visible as coloured fluorescent spots, whose number, R_F-values and fluorescent colours are characteristic for the genuine natural waxes.     

Solvent-free slack wax de-oiling—Physical limits

In order to get more knowledge about the fundamentals of solvent-free slack wax de-oiling by melt crystallization, investigations on multicomponent paraffin waxes have been performed, which included X-ray powder diffraction and optical microscopy. The tested neutral oil and medium slack waxes consisted mainly of n- and iso-paraffins with different chain lengths. The results suggest that only n-paraffins formed orthorhombic crystals at room temperature with c-axes corresponding to the average chain length of the paraffin waxes. The crystals were surrounded by less crystalline, rather amorphous, solid phase containing mainly iso-paraffins. The typical solid–solid transition of crystal lattice in neutral oil slack waxes from orthorhombic to hexagonal system at temperatures below melting point increases the mobility of the low melting components. This is the key for the applicability of the melt crystallization process. Investigations on sweating suggest a strong influence of the n-paraffins content on mechanical stability of crystal structures and on the separation efficiency of sweating.     

Lignocellulose–polymer composite. III

A linear relationship was achieved between the polymer load and the monomer concentration up to 200% when china clay or talc replaced the glass in the initiating system, sodium bisulfite–soda lime glass, for the free-radical graft polymerization reactions using semichemical pulp of bagasse as substrate. The results showed that china clay is better than talc, which may be contributed to the difference in their network structure. The properties of the composites prepared from the cografted semichemical pulp–polymethyl methacrylate revealed that the china clay leads to composites with high compression strength and hardness. Deformation percent increased with increasing polymer load. However, decreasing or increasing the polymer load affects the properties of the composites up to a limit, where there is a maximum or minimum for both compression strength and hardness at china clay ratio of 2 or 3. Composites were also prepared from poly(methyl methacrylate)-cografted-pith of bagasse using the initiating system sodium bisulfite in the absence or presence of soda lime glass. Compression strength, deformation percent, and hardness increased on decreasing the glass ratio from 1 to 0, at nearly the same polymer load. The presence of waxes and resins decreased the compression strength of the composites prepared by impregnation of the lignocellulose in polymer solution. The hardness of these composites increased on removing waxes and resins. Removal of part of hemicellulose by alkali treatment of the lignocellulose has increased the effect on hardness. Alkali treatments of the substrates lead to a high deformation percentage. The compression strength of alkali-treated lignocellulose are lower than the untreated ones. The change of compression strength to deformation percent and the compressibility due to complete removal of waxes and resins by the extraction with methanol–benzene or partial removal of the waxes, resins, and hemicellulose through alkali treatment followed the change of both the compression strength and percent of deformation. Water uptake of the composites prepared in this work was ranged between 6.8 and 7%. After 48 h the water uptake increased to the range 8.5–14.1%. Impregnation of the composites in water for 72 h increased the water uptake to the range 10.2–18.1%. © 1993 John Wiley & Sons, Inc.     

The Extended Community-Level Effects of Genetic Variation in Foliar Wax Chemistry in the Forest Tree <Emphasis Type="Italic">Eucalyptus globulus</Emphasis>

Genetic variation in foundation trees can influence dependent communities, but little is known about the mechanisms driving these extended genetic effects. We studied the potential chemical drivers of genetic variation in the dependent foliar community of the focal tree Eucalyptus globulus. We focus on the role of cuticular waxes and compare the effects to that of the terpenes, a well-studied group of secondary compounds known to be bioactive in eucalypts. The canopy community was quantified based on the abundance of thirty-nine distinctive arthropod and fungal symptoms on foliar samples collected from canopies of 246 progeny from 13 E. globulus sub-races grown in a common garden trial. Cuticular waxes and foliar terpenes were quantified using gas chromatography - mass spectrometry (GC-MC). A total of 4 of the 13 quantified waxes and 7 of the 16 quantified terpenes were significantly associated with the dependent foliar community. Variation in waxes explained 22.9% of the community variation among sub-races, which was equivalent to that explained by terpenes. In combination, waxes and terpenes explained 35% of the genetic variation among sub-races. Only a small proportion of wax and terpene compounds showing statistically significant differences among sub-races were implicated in community level effects. The few significant waxes have previously shown evidence of divergent selection in E. globulus, which signals that adaptive variation in phenotypic traits may have extended effects. While highlighting the role of the understudied cuticular waxes, this study demonstrates the complexity of factors likely to lead to community genetic effects in foundation trees.     

Einfluß von Wachsen auf Haft- und Gleitreibung

Influence of Waxing on Adhering and Sliding Friction A new method has been developed for determining the adhering and sliding friction. By this method, the influence of the films of caring agents on the nonskid properties can be determined very accurately. Novel finding of the present work is that by multiple measurements and mathematical-statistical evaluation valid statements can be made on the nonskid properties of floors. Furthermore, it could be shown that, in the rule, ester waxes have a positive effect on the nonskid properties.     

Einfluß der Raffination auf die Zusammensetzung der Säuremontanwachse

Refining Effect on Acid Montana Wax Composition Three acid montana waxes which result from industrial refining process in ZA Kedzierzyn were investigated with respect to their group composition and chemical composition. The subsequent wax types were investigated: 1. wax MR - weakly refined (one step, by HNO₃), 2. wax MR moderately refined (two step, by HNO₃ and Na₂Cr₂O₇), 3. wax R - highly refined (two step, by Na₂Cr₂O₇). These acid waxes were used in Poland as raw materials for production of various semisynthetic montana waxs. The characteristical values of the waxes have been determined. Besides that the examined acid montana waxes were separated by ion exchange methods and adsorption chromatography in free and esterified wax acids, wax alcohols and hydrocarbons. By GC methods the components separated from the substance groups have been qualitatively and quantitively analyzed. The effect of the refining methods on the chemical conversion processes of the waxes is explained.     

Über die Zerlegung von Kohlenwasserstoff-Gemischen mit Hilfe selektiver Extraktionsmethoden × — Zerlegung von Gatschen aus einem paraffinbasischen Rohöl

The Analysis of Hydrocarbon Mixtures with the Help of Selective Extraction Methods × — Analysis of Crude Waxes from a Paraffin Based Crude Oil The analysis of three crude waxes from different fractions of paraffin based crude oil, with the help of solid-liquid extraction and finally by urea-adduct formation, is reported. On the basis of selected physical data and suitable diagrams, the structural composition of the hydrocarbon components of these three crude waxes is discussed.     

Evaluating the Oil‐Gelling Properties of Natural Waxes in Rice Bran Oil: Rheological,Thermal, and Microstructural Study

The main objective of this research was to enhance the understanding of the oil‐structuring properties of natural waxes. A number of natural food‐grade waxes were evaluated for their oil‐gelling properties using a combination of techniques, including rheology, differential scanning calorimetry, and polarized light microscopy. Based on the rheological measurements (oscillatory, flow, and thixotropic behavior), we found that rice bran wax, carnauba Brazilian wax and fruit wax showed weak gelling behavior in rice bran oil (prepared at concentrations as high as 5 % w/w), exhibiting relative low elastic moduli that displayed a high frequency dependency. On the contrary, carnauba wild wax, berry wax, candelilla wax, beeswax, and sunflower wax were efficient oleogelators forming strong gels at concentration of <2 % w/w. We attempt to explain these observed differences in gelling behavior by crystal morphology, network formation, and the final amount of crystalline phase.     

Organogel Formation of Soybean Oil with Waxes

Many waxes including plant waxes and animal waxes were evaluated for the gelation ability toward soybean oil (SBO) and compared with hydrogenated vegetable oils, petroleum waxes and commercial non-edible gelling agents to understand factors affecting the gelation ability of a gelator. Sunflower wax (SW) showed the most promising results and all SW samples from three different suppliers could make a gel with concentrations as low as 0.5 wt%. Candelilla wax and rice bran wax also showed good gelation properties, which, however, varied with different suppliers. Gelation ability of a wax is significantly dependant on its purity and detailed composition. A wax ester with longer alkyl chains has significantly better gelation ability toward SBO than that with shorter alkyl chains indicating that the chain length of a component in a wax such as wax ester is an important factor for gelation ability. The SW–SBO organogel showed increased melting point with increased SW content, showing the melting point range from about 47 to 65 °C with 0.5–10 wt% SW. The effects of cooling rate on crystal size and firmness of a gel were investigated. The dependence of firmness on cooling rate was so significant that the desired texture of an organogel could be achieved by controlling the cooling rate in addition to controlling the amount of gelling agent. This research reveals that a small amount of food grade plant waxes including SW may replace a large amount of the hardstock containing trans-fat or saturated fat.