A new test method for determination of wax content in crude oils,residues and bitumens

A new method for determining wax content in petroleum materials is developed. It is based on thin layer chromatography with flame ionization detection (TLC-FID) and involves two-step development with two solvents. The principle of the test method is first to separate saturates from other more polar components based on good solubility of saturates in n-heptane and weak strength of interaction with an adsorbent (silica). Waxes are then separated from the saturate fraction using a poor solvent methyl-ethyl ketone (MEK) at such a low temperature (typically ?20 °C) that waxes are in solid state. The separated fractions are quantified with FID. The test method is verified using various model compounds including n-alkanes of different molecular weight, isoalkane, as well as commercial waxes. Results indicate that the TLC-FID method detects the waxes mainly composed of n-alkanes ranging from C20 to C40, and large isoalkanes and cycloalkanes which are soluble in n-heptane. The method has been satisfactorily applied to a variety of samples of crude oils, residues, and bitumens. It is simple, quick, and reliable. By changing MEK temperature in the development chamber, waxes may be further characterized.     

Organogelation Capacity of Epicuticular and Cuticular Waxes from Flax and Wheat Straws

Valorization of the agri-food industry by-products could contribute to curb issues related to food security and environmental problems. Flax and wheat seeds are major products of this industry, but their production is associated with tons of straws that can be valorized for their cuticular and epicuticular waxes. We aimed to determine the organogelation capacity of epicuticular waxes in comparison to cuticular waxes from both flax and wheat straws. Epicuticular waxes from flax and wheat straws have structured canola oil at 2% and 4% (w/w), respectively, whereas cuticular waxes from flax and wheat straws required critical concentrations of 4% and 5% (w/w), respectively. Characterization of the organogelation capacity (onset of crystallization temperature, temperature of phase transition, crystal morphology, solid fat, crystalline structure, and oil binding capacity) was also carried out. The high onset of crystallization temperature (38.1 ± 1.2°C), the phase transition at high temperature (38 ± 1.5°C), and capacity to structure canola oil at low concentration showed that epicuticular wax from flax straw is a promisor fat substitute, presenting organogelation properties comparable to the best results obtained in the literature for other vegetal waxes.     

High molecular weight waxes from Short Path Distillates of vacuum residue

Short Path Distillates of vacuum residue (boiling above 545 °C) is taken as feedstock for this study. Wax from this fraction is separated by solvent extraction method using methyl iso-butyl ketone (MIBK) as solvent. Both wax and the feedstock are characterised with the help of ASTM and IP procedures. Separated wax is fractionated at different temperatures, say 0–30 °C using MIBK as solvent. High temperature gas chromatography (HTGC) technique is used to study the distribution of alkane carbon number in all the fractions. It is observed that the wax contains very high molecular weight hydrocarbons as high as C₆₇H₁₃₆. HTGC technique as well as the Differential Scanning Calorimetry (DSC) indicates that all the fractions of the wax contain two types of hydrocarbons, one having high molecular weight alkanes (> 600) and another having low mol. wt. alkanes (~ 400). Thermal analysis by DSC technique further indicates that the wax is microcrystalline in nature having a low degree of crystallinity, 17%, as evidenced by XRD studies. Both high and low molecular weight waxes can also be separated based on their solubility characteristics.     

Separation of different paraffin wax grades using two comparative deoiling techniques

One stage fractional crystallization and solvent percolation techniques have been used to separate different grades of paraffin waxes; with different characteristics; from El-Ameria light, middle and heavy slack waxes. The two deoiling techniques were performed using ethyl acetate and butyl acetate solvents at ambient temperature of 20 °C, at different dilution solvent ratios (S/F by weight) ranging from 2:1 to 8:1 and constant washing solvent ratio of 2:1 for the first technique and at different percolation solvent ratios ranging from 4:1 to 14:1 for the second one. The resulting data revealed that fractional crystallization technique is more suitable for deoiling the heavy slack wax using butyl acetate solvent than the percolation technique. While, percolation technology is a preferable technique using ethyl acetate or butyl acetate solvent for separation of paraffin waxes from light and middle slack waxes.     

Fischer-tropsch waxes. II. Crystallinity and physical properties

The density, congealing point, and hardness were considered in relation to crystallinity, determined by an infra-red spectrometric method, of a series of waxes which are fractions from crude Fischer–Tropsch wax. Values ranging between 65 and 93, expressed as molecular percentages of crystalline material present, have been obtained. Data on molecular weights and physical properties were available. Smooth curves could be drawn for the variations of density, congealing point and hardness (or rather penetration) with molecular weight, but only for the more highly crystalline waxes. Two waxes, with crystallinities below 75, were found to have abnormally low congealing points and densities and to be abnormally soft, in relation to their molecular weights. This can be explained in terms of the less dense packing of molecules in the amorphous state. The effect of crystallinity on density was examined more closely, and a set of equations expressing the relationship between these entities and molecular weight was derived. These contain an unknown factor, however, which is dependent upon molecular weight distribution.     

Polyurethane‐acrylic hybrid emulsions with high acrylic/polyurethane ratios: Synthesis,characterization, and properties

Allyl polyoxyethylene ether (APEE) was used as coupling agent between polyurethane (PU) and acrylic polymer (AC) to synthesize stable waterborne polyurethane‐acrylic (PU‐AC) hybrid emulsions with high AC/PU weight ratio ranged from 45/55 to 70/30. The effect of the AC/PU weight ratio and the acrylate type including methyl methacrylate (MMA), butyl acrylate (BA) and mixture of them on the properties of the synthesized emulsions and resultant films were investigated. The research results showed that the colloidal particle of the emulsions behaved core‐shell structure, and the copolymers were not crosslinked. An increase in the AC/PU weight ratio led to an increase in the average particles size and the particle size distribution, but decrease in the viscosity of the emulsions. Meanwhile, the molecular weight distribution of the copolymers became wide, and the tensile stress, shore A hardness, storage modulus, glass transfer temperature, water resistance, and water contact angle of the resultant films increased, except that the films of PU‐BA were too soft to determine their mechanical properties. MMA and BA can provide the PU‐AC hybrid emulsions with very different properties, and which can be adjusted according to the special application. It was suggested that APEE can not only built up chemical bonds between PU and AC, but also increase the self‐emulsifying ability in the emulsion polymerization due to its hydrophilic ethylene oxide and carboxylic groups, resulting in that PU‐AC hybrid emulsions with high AC/PU ratio can be obtained by this method. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44488.     

Untersuchungen vollsynthetischer Kohlenwasserstoff-Wachse

Investigation of Fully Synthetic Hydrocarbon Waxes Methods for the structural investigation of synthetic hydrocarbon waxes of a new series of Ruhrwaxes are reported. Besides the molecular weight distribution, which is determined by fractional extraction of the hydrocarbon waxes with an organic solvent and characterization of the fractions by means of molecular weights, solidification points and refractive indices, properties like ability to form adducts with urea, dilatometric and calorimetric measurements as well as assay of IR spectra serve for elucidating the structure and composition.     

The influence of molecular weight on the melt rheology of polypropylene

Melt viscosity and melt elasticity data were obtained over a broad range of temperatures and shear rates on a series of four polypropylenes of different molecular weight but approximately the same molecular weight distribution. The superposition technique was used with both temperature and molecular weight to shift flow curves for all four materials at three temperatures each along the shear rate axis to generate a master flow curve at a given temperature and molecular weight. For polypropylenes of this type, and molecular weight distribution shift, factors which can be used to extend the useful range of experimentally obtained flow data were determined. The dependency of apparent viscosity on weight average molecular weight at shear stresses as high as 10⁶ dynes/cm² is shown. The dependency of melt elasticity on molecular weight and temperature is discussed.     

Fischer-tropsch waxes. IV. Qualitative and quantitative investigation of chain branching

The degree of branching of waxes, expressed as the number of branches per 100 carbon atoms, is important because it determines crystallinity, which in its turn influences physical properties. Among several methods available for the study of branching, an infra-red spectrometric method was chosen. It consisted of the determination of methyl groups. It was also necessary to determine molecular weight. The most serious problem encountered was the variation of the specific absorbance at the chosen frequency (1379 cm^?1) with the structural position of the methyl group, which necessitated a thorough qualitative investigation of the branches, using infra-red, nuclear magnetic resonance and mass spectrometry. It was shown that branches in the Fischer-Tropsch waxes are almost entirely methyl and that the branching is seemingly distributed statistically along the chains. Calibration was effected with pure n- and mono-methyl paraffins, making the determination of degree of branching possible. This method can be applied to other materials provided that certain structural features about them are known.     

Synthesis,characterization and polymerization of waxy monomers

Waxy monomers and crosslinkers, respectively, were synthesized from commercially available waxes by esterification with 2-hydroxyethyl methacrylate, glycerol dimethacrylate, or glycidyl methacrylate or by functionalization with 2-isocyanatoethyl methacrylate. The resulting opaque methacrylates with melting points between 45 and 80°C were polymerized in bulk and in toluene solution in presence of free radical initiators. The obtained polymers were characterized by a broad molecular weight distribution. Opposite to the bulk polymerization, the double bond conversion in solution polymerization is nearly quantitative. The observed volume shrinkage during polymerization is very low due to the high molecular weight of the monomers. Polymerizates containing crosslinking comonomers exhibit improved mechanical stability.     

Extraction of Surface Wax from Whole Grain Sorghum

Sorghum has potential as a domestic source of wax for applications in the food and nonfood industries. The waxes extracted from sorghum have similar physical properties to those of Carnauba wax, a common imported commercial wax. This work focused on the extraction, fractionation, and characterization of waxes from sorghum kernels. Extraction was performed by varying the extraction conditions including temperature and solvents (hexane, ethanol, and methanol). A fractionation technique was developed to separate and quantify waxes from nonwaxes. The fractions were then characterized using a reverse‐phase high‐performance liquid chromatography method developed in our laboratory that utilizes an evaporative light‐scattering detector for quantification. The results showed that the average amount of wax extracted from the surface of intact sorghum kernels was about 0.3 wt% using hexane at temperatures between 25 and 120°C and 1000 psi. The yield of wax via hexane extraction increased with temperature and ranged from about 0.06 to 0.39 wt%. Extraction with alcohols resulted in higher yields of extracts, but after fractionation to remove nonwax components, the yield of waxes was reduced by 31% for ethanol and 47% for methanol compared to hexane.     

Migration behaviors of antiozonants to the surface in NR vulcanizates,depending on the season: The effect of wax

Influence of wax film on the surface of a rubber vulcanizate on migration of antiozonants was studied using NR vulcanizates containing various types of waxes. The waxes have different molecular weight distributions. N‐phenyl‐N′‐isopropyl‐p‐phenylenediamine (IPPD), N‐phenyl‐N′‐(1,3‐dimethylbutyl)‐p‐phenylenediamine (HPPD), N,N′‐di(sec‐butyl)‐p‐phenylenediamine (SBPPD), and N,N′‐di(1,4‐dimethylpentyl)‐p‐phenylenediamine (DMPPD) were used as antiozonants. Migration experiments were performed outdoors for two months in the summer, fall, and winter. The migration rates of the antiozonants in the vulcanizate without wax are faster than those in the vulcanizates with waxes. The antiozonants migrate slower in the vulcanizate containing wax with a high‐molecular‐weight distribution than in the vulcanizate with a low one. In the summer, the migration rates of SBPPD and DMPPD are faster than those of IPPD and HPPD, respectively. But, in the fall, the migration rates of SBPPD and DMPPD are slower than those of IPPD and HPPD, respectively. The differences of migration behaviors of the antiozonants, depending on season and wax type, was discussed. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1987–1993, 1999     

The compositions of some unhydrolyzed naturally occurring waxes,calculated using functional group analysis and fractionation by molecular distillation,with a note on the saponification of carnauba wax and the composition of the resulting fractions

Summary Methods for the determination of acid, ester, hydroxyl, and ketone (or aldehyde) groups and of mean molecular weights of small samples of natural waxes are reported. Complete analyses can be made on 0.5 g. of sample. A simplified procedure for quantitative separation of acid and unsaponifiable fractions of a wax is also reported. Molecular distillations of beeswax, caranda wax, crude and refined candelilla wax, and ouricury wax, have fractionated these complex mixtures into simpler ones. Hydrocarbons and free unsubstituted alcohols and acids, if present, distil readily at 150°C. A pot still suitable for convenient molecular distillation of up to 100-g. charges of waxes or other high melting materials is described. A method for the calculation of composition of unhydrolyzed waxes based upon function group analysis of molecular distillation fractions is described. Results of application of this method to the waxes distilled are reported and show the ubiquitousness of hydroxy acids. All of the above waxes and carnauba wax contain major proportions of esters of the hydroxy acids, and none contains as much as one-half simple esters of unsubstituted acids and alcohols. A portion of a dissertation submitted by Thomas Wagner Findley to the Graduate School of the Ohio State University in partial fulfilment of the requirements for the Ph.D. degree. S. C. Johnson and Son Inc. Fellow in Physiological Chemistry, 1946-50.     

Fischer–tropsch waxes. III. Indications of molecular order in molten wax

Although paraffins cannot form liquid crystals, evidence of the existence of some kind of molecular order at temperatures above their melting points can be found in the literature. When the infra-red spectra of certain Fischer–Tropsch waxes were recorded at different temperatures, it was noticed that the intensity of the 1303 cm^?1 band (A₁₃₀₃), which is due to methylene groups in amorphous regions, was abnormally low just above the melting points of the waxes. At higher temperatures the intensity rose to a maximum followed by the normal decline. This effect was shown most strikingly by super-hard wax, which has a high crystallinity and high average molecular weight. A dilatometric experiment with super-hard wax showed that the specific volume rises linearly from the melting point (111°) to ～ 125°. At higher temperatures, although the volume continues to rise linearly, the slope is reduced by 11%. The explanation presented for both phenomena is that bundles of molecules are present above the melting point. They are remnants from crystallites and disappear at ～ 125°. in the case of super-hard wax. Upon cooling, however, the ordering of molecules only starts taking place near the congealing point. This is borne out by the linear changes in A₁₃₀₃ and specific volume that have been observed.     

The investigation of relaxation mechanism and model of polystyrene in high-elastic state

The relaxation behavior of polymer in its high elastic state is a key factor which determines the molding process and accuracy of its products. Polystyrene with different molecular weights are selected as research object and its relaxation time at different temperatures was tested by torque rheometer. Combining the relationship of “temperature-relaxation time”, to deeply analyze its relaxation mechanism, a physical model of high elastic relaxation time of polystyrene based on the movement of molecular chains was established, and the change of the physical model at different temperatures was explained. The corresponding mathematical model was obtained by analyzing the influence of the weight average molecular weight M_w, dispersion D, and temperature T parameters of polystyrene on its relaxation time. The results of experiments and model calculations reveal that the relaxation time of polystyrene under high elasticity does not continue to decrease with the increase of temperature, but it changes in an M-shape with the increase of temperature, that is, the relaxation time shows an upward trend at 155°C – 160°C and a downward trend at 160°C – 165°C. It has an increasing trend at 165°C – 170°C, and a decreasing trend at 170°C – 175°C. Polystyrenes with different molecular weights and dispersion degrees have different M forms. The research results have theoretical guiding significance for polymer processing.     

Reversible addition-fragmentation chain transfer polymerization of 7-(4-(acryloyloxy)butoxy)coumarin

The light sensitive vinyl monomer with coumarin unit, 7-(4-(acryloyloxy)butoxy)coumarin (7AC), was synthesized. The reversible addition-fragmentation chain transfer (RAFT) polymerization of 7AC, initiated by 2,2′-azobisisobutyronitrile (AIBN), was carried out using 2-cyanoprop-2-yl dithiobenzoate (CPDB) as a RAFT agent in N,N-dimethylformamide (DMF) solution. The kinetics exhibited first-order relationship with respect to the monomer concentration. The molecular weight of the polymer increased linearly with the monomer conversion. The chain extension of poly(7-(4-(acryloyloxy)butoxy)coumarin) (P7AC) using styrene (St) as the second monomer demonstrated that the obtained polymers were almost “living”. The fluorescence intensity of P7AC increased with the molecular weight of P7AC and was stronger than that of the monomer. The obtained polymer had strong ultraviolet (UV) absorption at 322 nm. The molecular weights of the polymer had no effect on its ultraviolet absorption intensity. The coumarin structure existing in P7AC underwent [2 + 2] cycloaddition reaction (photodimerization) under UV irradiation in tetrahydrofuran (THF) solution, which can be further used to prepare small particles from the single polymer.     

Ultra-high modulus polyethylene. 1 Effect of drawing temperature

Drawing behaviour and the properties of ultra-drawn high density polyethylene have been investigated as a function of the drawing temperature. An optimum temperature has been found for each type of polyethylene, at which the best drawing behaviour is found. It appears that the temperature range for effective drawing (leading to a high draw ratio and high Young's modulus) depends on the molecular weight and its distribution. The temperature range of the effective drawing is shifted towards higher temperatures for polyethylene exhibiting broader molecular weight distribution and higher weightaverage molecular weight. Ultra-high modulus and transport samples have been obtained by drawing high density polyethylene with broad molecular weight distribution ($\text{M}\text{?}{}_{\mathrm{w}}\text{M}\text{?}{}_{\mathrm{n}}\text{～ 20}$ and $\text{M}\text{?}{}_{\mathrm{w}}\text{～ 200 000}$) at higher drawing temperatures. It has been found that in the range of drawing temperatures 80–105°C the modulus of this polyethylene is higher for samples drawn at higher temperatures. Transparent samples with draw ratios of 35–40 and with Young's moduli of 600–650 kbar (at room temperature) have been obtained by drawing the polyethylene at 100°–105°C. We conclude that the high molecular fraction in the polyethylene, forming tie molecules in the drawn material, is responsible for the high modulus, while the low molecular weight fraction facilitates alignment of the long chains and retards the internal voiding (whitening) to a very high draw ratio during drawing at the higher temperatures.     

Thermogravimetrische Wachsanalyse

Analysis of Waxes by Thermogravimetry A series of low molecular weight paraffins, micro-crystalline waxes, Fischer-Tropsch-paraffins and polyethylene paraffins were studied by thermogravimetry. Low molecular weight hydrocarbons could be clearly distinguished from each other, whereas with increasing molecular weight the differences became smaller. Mixtures of two components can be analyzed under certain circumstances.     

Wax crosslinking with dicumyl peroxide

A Fischer—Tropsch paraffin wax of high molecular weight, congealing point 205°F (96·1°C), was crosslinked with dicumyl peroxide as initiator. At peroxide/wax molar ratios of less than 1·15 : 1, crosslinked waxes with molecular weights up to approximately double that of the starting material are obtained. These products are characterised by an increase in elasticity. At peroxide/wax ratios greater than 1·15 : 1 insoluble and infusible gels are formed. The efficiency and fate of the initiator and possible side reactions are discussed.     

Preparation of high molecular weight poly(N‐vinylcarbazole) in high yield by low‐temperature precipitation polymerization of N‐vinylcarbazole

To produce high molecular weight poly(N‐vinylcarbazole) (PVCZ) with high conversion, N‐vinylcarbazole (VCZ) was heterogeneously polymerized in methanol at 30, 40 and 50 °C using a low temperature initiator, 2,2′‐azobis(2,4‐dimethylvaleronitrile) (ADMVN), and the effects of polymerization temperature and concentration of initiator and solvent on the polymerization behaviour and molecular parameters of PVCZ investigated. Globally, experimental results correspond to predicted ones. Low polymerization temperature using ADMVN and a heterogeneous system using methanol proved to be successful in obtaining poly(N‐vinylcarbazole) (PVCZ) of high molecular weight and high conversion with small temperature rise during polymerization, although free radical polymerization by azoinitiator was used. The polymerization rate of VCZ in methanol at 30 °C is proportional to the 0.88th power of ADMVN concentration. The molecular weight is higher and the molecular weight distribution is narrower with PVCZ polymerized at lower temperatures. For PVCZ produced in methanol at 30 °C using an ADMVN concentration of 0.0001 mol/mol of VCZ, a weight average molecular weight of 1 750 000 g mol⁻¹ is obtained, with a polydispersity index of 1.82 © 2000 Society of Chemical Industry