Increase In Wax Content Research Articles

The Effect of Waxes on Rapeseed Oil Quality and Acrylamide Development in Potato Fries during Deep-Frying

This paper analyzed the effects of adding rice bran wax (RW) and beeswax (BW) to rapeseed oil as a deep-frying medium and the quality parameters of potato fries, including acrylamide contamination. It was found that the addition of RW and BW caused an increase in the oil’s acidity. However, oil deterioration based on peroxide values and fatty acid profiles did not differ very much from the oil without waxes. The study showed that the addition of rice bran wax at the level of 2.5 g/L of rapeseed oil was able to significantly decrease oil uptake in potato fries. The addition of waxes did not influence the color parameters in the first frying cycle; however, changes were observed later. The browning index indicated that 10 g of BW per liter may darken fries in comparison to rapeseed oil without additives. It was found that with an increase in wax content in the frying medium, potato fries contained more acrylamide.

Processability and physico‐mechanical properties of ultrahigh‐molecular‐weight polyethylene using low‐molecular‐weight olefin wax

AbstractThe influence of molecular weight of olefin wax as a plasticizer on the processability and properties of ultrahigh‐molecular‐weight polyethylene (UHMWPE) was thoroughly investigated in this study. Two different grades of olefin wax (H5 and 210P) were used separately to plasticize UHMWPE. Comparative results were analyzed based on mixing torque, mechanical, thermal, thermo‐mechanical, and morphological aspects. The Gaussian mathematical model was applied to the internal thermo‐shear batch mixing torque data to predict processability and plasticization of the resulting compounds. A decrease in the peak torque value with increase in wax content revealed the plasticization effect. Across both types of wax (H5 and 210P) at 4, 8, and 10 phr content, the 10 phr H5 wax plasticized UHMWPE batch showed a minimum peak torque of 4.5 Nm with a broad mixing temperature window (∆T) of 32.4°C. The relatively low‐molecular‐weight wax (H5) seemed to be more efficient at uncoiling the entanglements among the amorphous phase of UHMWPE, perhaps because of its smooth interpenetration between ties. The lowest degree of crystallinity range (34%–40%) and the highest nucleation rate (0.9 min−1) were found with 10 phr H5 wax plasticized UHMWPE. The tensile strength of 30.5 MPa and elastic modulus of 127 MPa, achieved by the addition of H5 wax at 10 phr loading, confirmed the optimum effect of plasticization. The plasticization effect was also established from the loss moduli and Cole–Cole plots (log loss modulus vs. log storage modulus). A smaller number of multiple stress‐induced overshoots and the inclining approach toward the viscous dominant regime with temperature sweep were observed in the case of 10 phr H5 wax composition. Scanning electron microscopy (SEM) analysis revealed disappearance of interfacial crazing and interparticle boundaries progressively with the increase in H5 wax content. Overall, plasticized UHMWPE with 10 phr content of H5 wax showed the optimum processability and properties.

Wax Deposition Law under a Gas-Liquid Bubbly Flow Pattern.

Under the high-pressure and low-temperature environment of the deep sea, wax deposition will occur in the wellbore. This study discusses the effect of gas–liquid two-phase bubbly flow on wax deposition. In this study, wax deposition experiments of a gas–liquid two-phase flow in vertical pipelines were carried out using waxy white oil and air as the experimental medium. The results show that under the bubble flow pattern, within a short period of time from the start of wax deposition, it rapidly accumulates to the peak, then rapidly cuts off part of it, and then presents a simple harmonic dynamic trend until the final stability. The average wax-deposit thickness decreases first and then increases with the increase of superficial gas velocity, and it increases first and then decreases with the increase of superficial liquid velocity. The average wax-deposit thickness decreases with the increase of oil temperature. The average wax-deposit thickness was substantially constant and then decreases with the increase of ambient temperature. The wax-deposit thickness increases with the increase of wax content in oil flow. This research is useful for people to further understand the changes in the wax deposition process.

Effects of waxes on hydrate behaviors in water-in-oil emulsions containing asphaltenes

In this study, the effects of waxes on carbon dioxide hydrate formation and dissociation in asphaltene-containing emulsions were systematically investigated using a high-pressure stirred autoclave equipped with an on-line viscometer. The results showed that the presence of waxes strengthened the inhibiting effect of asphaltenes on hydrate formation. Specifically, the induction time increased and the amount of formed hydrates decreased with increasing wax content in water-in-oil emulsion containing asphaltenes. The results indicated that waxes increased the viscosity of emulsions. It was observed that wax crystals dispersed in the bulk phase and got adsorbed at water–oil interface through the synergistic effect with asphaltenes. Furthermore, waxes inhibited the dissociation of hydrates in these emulsions. Both the gas emission rate and the average rate of hydrate dissociation decreased with an increase in wax content. The possible mechanisms were proposed to illustrate the effects of waxes on hydrate formation and dissociation in asphaltene-containing water-in-oil emulsions.

The phase behavior and solubilization ability of nonionic surfactant-distillate fraction of crude oil microemulsion system

In this paper, phase behavior in temperature scanning of E1305/distillate fractions/water/n-butyl alcohol microemulsion system were investigated. And the effect of surfactant concentration and oil type on microemulsion solubilization ability was studied. In the research, the content of saturates, aromatics, resins and asphaltenes in distillate fractions of crude oil was analyzed. The change of phase inversion temperature (PIT), solubilized ability and temperature caused by different compositions of distillate fraction was investigated. According to the experimental results, the phase behavior of temperature scanning was Winsor Ⅰ → Winsor Ⅲ → Winsor Ⅱ. The ability of solubilizing microemulsion was improved by increasing the surfactant content. The temperature of optimum solubilization was decreased with the increase of surfactant content. When the type of oil phase was changed, the solubilized ability of microemulsion was decreased with the increase of distillation temperature. And the optimum solubilization temperature was increased. According to the results, this phenomenon was caused by the increase of wax content and equivalent alkane carbon number.

Investigations of temperature and dilution effect on rheological properties of waxy crude oil

The purpose of the paper is to study the effect of temperature and hydrocarbon solvent addition on thixotropy of waxy crude oil. Oil is a complex multicomponent hydrocarbon system. There are many interactions between wax and asphaltene, wax and aromatics, asphaltene and resins in original oil. For example, the dispersion of asphaltenes is known to be influenced by resins. The resins are adsorbed onto the surface of the asphaltenes, whereby the asphaltenes are not aggregated. Wax is adsorbed by fine asphaltene particles and wax appearance temperature (WAT) observed at low temperature (formed wax crystals too small to be detected by measuring system). The authors of the paper have studied the separate effect of two solvents (kerosene and diesel fuel), wax concentration and impurities (kaolinite) on WAT to understand how all these factors affect WAT in wax-bearing solutions individually. Wax-bearing solutions in wax concentration range from 10 to 60% by weight were investigated by the visual and rheological methods under atmospheric pressure. It is shown that the diesel-based solutions have higher WAT than the kerosene-based solutions. Studies have shown that the increase in wax concentration in solution leads to an increase in WAT. The paper describes that the addition of impurities (kaolinite) to the solutions resulted in an increase in WAT. Besides, it is shown that WAT obtained by rheological method is higher on average of 1 °C than WAT obtained by visual method. The authors suggested that under constant other conditions (pressure, resin and asphaltenes content, etc.) an increase in wax content in oil and the content of impurities will lead to an increase in WAT. The scientific basis for this conclusion is that, in the future we can, adding or removing from solution hydrocarbon components, with certain assumptions, simulate the properties of oil. In particular, this will allow us to study separate interactions between the wax and asphaltene, wax and aromatics, and wax and naphtha compounds, and abstract away from other factors. The waxy crude oil production in the Samara region is complicated by impurities entrainment and non-Newtonian properties of oil. The investigations of waxy crude oil were provided with light scattering method (in near infrared region), microscopy under high pressure with the grain size analysis (visual) and a rheological method. We obtained the unique «viscosity superanomaly» discovered by Vinogradov and Malkin (Rheol Acta 5(3):188–193, 1966) at low temperatures and shear stress by rheological method under atmospheric pressure. The area of the hysteresis loop on the flow curve increases as the temperature decreases, which is caused by the formation of the lattice by wax. We have also shown that the use of solvent and the increase in temperature allow to reduce «viscosity superanomaly». Simultaneous use of light scattering and microscopy under high-pressure methods allows increasing in accuracy of measuring. For waxy crude oil, there will also be a difference between rheological and visual methods of WAT measuring, as these methods have different sensitivity limits. Besides, the study showed that addition of N2 and CO2 to oil leads to decrease in WAT. However, it is necessary to provide a number of additional studies before gas injection projects in the field. For example, it is shown that CO2 injection leads to asphaltenes precipitation in oil by many scientists. Novelty of the paper consists in investigation of rheological properties of waxy crude oil of the Samara and the effect of nonhydrocarbon gases on WAT. In this study, unique flow curves of oil of the Samara region were obtained.

Study on the Effect of Crude Oil Composition on Waxing Characteristics of Waxy Crude Oil

The waxing deposition characteristics of crude oil is of great significance to the exploitation and transportation of high waxy crude oil. Therefore, three series of simulated crude oils were prepared on the basis of composition analysis and composition remixing of crude oil. The carbon distribution of oil samples and their corresponding wax components were analyzed by high temperature gas chromatography. The variation of waxing point, peak temperature and average exothermic enthalpy of these simulated crude oils were measured by Differential Scanning Calorimetry (DSC). The results showed that the increase of resin and asphaltene content had little effect on the waxing apprearance temperature (WAT) and Wax precipitation peak temperature (WAPT). The increase of aromatics content significantly decreased them, while some asphaltene may precipitate. The increase of wax content will greatly increase these two temperature, which is detrimental to the wax removal by heating method.

Structural, morphological and mechanical properties of gamma irradiated low density polyethylene/paraffin wax blends

The effect of gamma irradiation on the lattice structure, surface morphology, and mechanical properties was invested for LDPE/ paraffin wax blend films. Blends of LDPE/wax in content of 100/0, 98/2, 96/4, 94/6, 92/8, 90/10 and 85/15 (w/w) were prepared by melt-mixing at the temperature of 150 °C and then irradiated by gamma irradiation. It was found that increasing the wax content more than 15% lead to phase separation. The effect of gamma radiation on the structure, surface morphology, and mechanical properties has been investigated using the X-ray diffraction, scanning electron microscope and mechanical tests. Both The blending and gamma irradiation process has an influence on the structure and consequently on the surface morphology of the samples. The values of lattice parameters were calculated. The grain size, inter chain distance and interplanar spacing decrease with increasing paraffin and increase with increasing gamma absorbed doses. While the dislocation density, the microstrain, and the distortion parameters increase with increasing paraffin wax content and decreases with increasing gamma absorbed doses. The obtained values from X-ray indicates that notable changes of the atomic lattice structure for both unirradiated and irradiated blends, which also confirmed by studying the surface morphology of all blends. It was found that an increase in wax content induces a linear decrease in tensile strength; elongation at break, Young's modulus, and hardness. A linear increase of these mechanical parameters was observed with increasing gamma absorbed dose. The final results show the reliability of gamma radiation as a practical method for the control of long-term properties.

An investigation on gas hydrate formation and slurry viscosity in the presence of wax crystals

Clarifying the interaction effect between hydrate and wax is of great significance to guarantee operation safety in deep water petroleum fields. Experiments in a high‐pressure hydrate slurry rheological measurement system were carried out to investigate hydrate formation and slurry viscosity in the presence of wax crystals. Results indicate that the presence of wax crystals can prolong hydrate nucleation induction time, and its influence on hydrate growth depends on multiple factors. Higher stirring rate can obviously promote hydrate growth rate, while its influence on hydrate nucleation induction time is complicated. Higher initial pressure will promote hydrate formation. Gas hydrate slurry shows a shear‐thinning behavior, and slurry viscosity increases with the increase of wax content and initial pressure. A semiempirical viscosity model showing a well‐fitting is established for hydrate slurry with wax crystals by considering the aggregation and breakage of hydrate particles, wax crystals, and water droplets. © 2018 American Institute of Chemical Engineers AIChE J, 64: 3502–3518, 2018

Measurement and Prediction of Time-independent and Time-dependent Rheological Behavior of Waxy Crude Oil

Wax deposition phenomenon changes the rheological behavior of waxy crude oil completely. In the current work, the rheological time-dependent and time-independent behaviors of waxy crude oil samples are studied and flow curve and compliance function are measured for the oil samples with various wax contents at different temperatures. A decrease in temperature and an increase in wax content lead to an increase in the viscosity and yield stress but a significant drop in compliance function. A modified Burger model is developed to predict the behavior of the compliance function and a modified Casson model is used to predict the flow curve of the waxy crude oil samples within a vast range of wax contents and temperatures. The proposed Burger and Casson models match with experimental results with R2 of 99.7% and 97.33% respectively.

Thermal behavior of gamma-irradiated low-density polyethylene/paraffin wax blend

ABSTRACTThe thermal properties of low-density polyethylene (LDPE)/paraffin wax blends were studied using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and melt flow index (MFI). Blends of LDPE/wax in ratios of 100/0, 98/2, 96/4, 94/6, 92/8, 90/10 and 85/15 (w/w) were prepared by melt-mixing at the temperature of 150°C. It was found that increasing the wax content more than 15% leads to phase separation. DSC results showed that for all blends both the melting temperature (Tm) and the melting enthalpy (ΔHm) decrease linearly with an increase in wax content. TGA analysis showed that the thermal stability of all blends decreases linearly with increasing wax content. No clear correlation was observed between the melting point and thermal stability. Horowitz and Metzger method was used to determine the thermal activation energy (Ea). MFI increased exponentially by increasing the wax content. The effect of gamma irradiation on the thermal behavior of the blends was also investigated at different gamma irradiation doses. Significant correlations were found between the thermal parameters (Tm, ΔHm, T5%, Ea and MFI) and the amount of wax content and gamma irradiation.

Influence of wax content on the electrical, thermal and tribological behaviour of a polyamide 6/graphite composite

Abstract In this study, the influence of wax content on the electrical, thermal and tribological properties of a polyamide 6 composite filled with 15% wt. graphite was investigated. The wax filler contents of the composite were by 2, 4 and 6 wt.%. Characterisation of the composites was obtained using a Fourier transform infrared spectroscopy test. Electrical performance tests were carried out, and the dielectric real values (ε′) and imaginary values (ε″) were recorded. Thermal differential scanning calorimetry tests were carried out, and the glassy and melting temperatures of the composite materials were recorded. Furthermore, tribological tests were carried out and the friction coefficient and wear rate of the composites were recorded. The results show that the increase in wax content led to the increase in the permittivity values (ε′ and ε″) of the composites. The increase in wax content also led to the decrease in the friction coefficient and wear rates of the composite materials. Furthermore, the glassy and melting temperatures of the composite materials showed a sensitivity to the wax content. Finally, it is concluded that optimum properties, in total, were obtained in the composite filled with 6 wt.% wax.

The effect of expanded graphite on the physical properties of conductive EVA/wax phase change blends for thermal energy storage

A study of the morphology, dynamic mechanical, impact, and tensile properties of ethylene vinyl acetate copolymer (EVA)/expanded graphite (EG) and EVA/wax/EG composites is presented. The composites were prepared by melt blending. The EVA/EG composites showed ductile behavior, while brittle behavior was observed in the presence of wax. A finer dispersion of EG was observed in the matrix when wax was present. The storage modulus of the EVA/wax/EG composite was higher than that of the EVA/EG composite, which is ascribed to a better interaction between the EVA and the wax‐covered EG that significantly reduced the EVA chain mobility. The composites showed a decrease in impact strength with increasing EG and wax contents. There was a significant difference in the elongation at break between the EVA/EG and EVA/wax/EG composites, and little change in Young's modulus of EVA in the presence of EG and with increasing EG content. However, Young's modulus of the EVA/wax blends increased in the presence of and with increasing EG content. In all the investigated samples containing EVA and wax, irrespective of the EG content, the stress at break decreased with an increase in wax content. POLYM. COMPOS., 37:3025–3032, 2016. © 2015 Society of Plastics Engineers

Studies on the Structural Characteristics of Gelled Waxy Crude Oils Based on Scaling Model

The structural characteristics of three gelled waxy crude oils were studied through DSC analysis, rheological test, and a scaling model for colloidal gels. The total wax content is 8.1 wt % for crude oil A, 11.5 wt % for crude oil B, and 17.3 wt % for crude oil C. The concentration of precipitated wax crystals, φW increases gradually with the decrease of temperature. The gelation point, which increases with the increase of wax content, is 16.5 °C for crude oil A, 26 °C for crude oil B, and 41 °C for crude oil C. The elastic modulus in linear region, GE′ of the gelled crude oils always increases with decreasing temperature while the critical linear elastic strain, γE of the gelled crude oils first decreases with decreasing temperature, then increases with the further decrease of temperature. The microstructure of gelled crude oils, which can be divided into strong-link region and weak-link region, is similar to that of colloidal gels. In the strong-link region, the GE′ increases but the γE decreases with i...

Structure and properties of phase-change materials based on high-density polyethylene, hard Fischer-Tropsch paraffin wax, and wood flour

Phase-change materials based on high-density polyethylene (HDPE), a hard Fischer–Tropsch paraffin wax (H1 wax), and alkali-treated wood flour (WF) were investigated. The blends and composites were prepared by melt-mixing. They were characterized in terms of their morphology as well as thermal, mechanical, thermomechanical, and water absorption properties. Although the scanning electron microscopy micrographs showed some evidence of intimate contact between WF and the HDPE matrix, there were poor filler dispersion and interfacial adhesion. The percentage miscibility of H1 wax in HDPE seems to have decreased with increasing wax content in the blends. A fairly strong affinity between the WF and H1 wax was noticed. There was plasticization of the HDPE matrix by the wax as well as inhomogeneity and uneven wax dispersion within the polymer matrix. The presence of H1 wax and WF influenced the crystallization behavior of the HDPE matrix. The incorporation of wax reduced the thermal stability of the blends and composites, but stabilized the WF. The H1 wax and WF differently influenced the viscoelastic properties of the HDPE matrix. In contrast to the blends where the tensile properties improved in the presence of wax, the composites showed poorer properties. An increase in wax content resulted in a decrease in water uptake by the composites. POLYM. COMPOS., 32:1155–1163, 2011. a 2011 Society

Structure and properties of phase change materials based on HDPE, soft Fischer‐Tropsch paraffin wax, and wood flour

AbstractPhase‐change materials based on high density polyethylene (HDPE), soft Fischer‐Tropsch paraffin wax (M3), and alkali‐treated wood flour (WF) were investigated. The blend and composite samples were prepared by melt mixing using a Brabender Plastograph, followed by melt pressing. They were characterized in terms of their morphology, as well as thermal, mechanical, thermo‐mechanical, and water absorption properties. Although SEM micrographs showed some evidence of intimate contact between the WF particles and the HDPE matrix as a result of alkali treatment, poor filler dispersion, and interfacial adhesion were also observed. Partial immiscibility of the HDPE and the M3 wax was noticed, with the WF particles covered by wax. There was plasticization of the HDPE matrix by the wax, as well as partial cocrystallization, inhomogeneity and uneven wax dispersion in the polymer matrix. The HDPE/WF/M3 wax composites were more homogeneous than the blends. The presence of wax reduced the thermal stability of the blends and composites. Both the presence of M3 wax and WF influenced the viscoelastic behavior of HDPE. The HDPE/M3 wax blends showed an increase in the interfacial amorphous content as the wax content increases, which resulted in the appearance of a β‐relaxation peak. The presence of M3 wax in HDPE reduced the mechanical properties of the blends. For the composites these properties varied with WF content. An increase in wax content resulted to a decrease in water uptake by the composites, probably because the wax covered the WF particles and penetrated the pores in these particles. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Comparison of LDPE, LLDPE and HDPE as matrices for phase change materials based on a soft Fischer–Tropsch paraffin wax

Phase change materials based on LDPE, LLDPE and HDPE blended with soft paraffin wax were studied in this work. The purpose of this study was to compare the influence of wax content on the thermal and tensile properties of PE/wax blends. It was found that the different polyethylene/wax blends were immiscible for the samples containing 30–50% wax. The presence of wax influenced the melting and crystallization behaviour of the different polyethylenes in different ways, and the thermal analysis results show that the waxes were evenly distributed in the polymer matrices and that there was no wax leaking during sample preparation. For all the blends the thermal stability decreased with an increase in wax content, and the PE/wax blends degraded in two clearly distinguishable steps. The presence of wax generally caused a reduction in tensile properties, but the extent of the wax’ influence depended upon the morphology of the polyethylene.

Frictional behavior of rolled surfaces coated with polymer films

Rolled aluminum sheet, coated with a lacquer or polymer film, is often subjected to forming operations. In some cases, the polymer coating incorporates an internal lubricant, which migrates to the surface during curing. The lubricants help to improve the runability of the coated sheet through forming operations such as stamping or deep drawing. In the present study, samples of rolled aluminum sheet were coated with polymer films of various thicknesses. The coating contained various concentrations of a wax lubricant additive. Two cooling regimes of coating application were studied. The cooling profile affects the mechanical properties of the coating, along with the amount of wax migrating to the surface. Friction testing was performed by means of the ball-on-flat friction test apparatus. It was found that the coating thickness has the most prominent effect on the coefficient of friction. In the case of thin coatings, an increase in wax content on the surface gave rise to the coefficient of friction. At intermediate polymer coating thicknesses, the coefficient of friction was found to be substantially independent of the wax level. However, for thicker coatings, increasing the wax level on the surface caused a drop in the coefficient of friction. These observations can be explained in terms of the indentation of the coating film by the ball, which affects the area of contact during the friction test. A model is proposed which takes into account both the coating thickness and wax lubricant level in a single analytical expression. This model is based on the concept of hydrodynamic lubrication. The modeling part of the present work was supported by study of the indentation of the coated sheet by a steel ball.

Thermal and mechanical properties of cross-linked and uncross-linked linear low-density polyethylene–wax blends

The influence of the wax content and different concentrations of the crosslinking agent on the thermal and mechanical properties of linear low-density polyethylene–wax blends has been investigated. It was found that an increase in wax content induces an increase in elastic modulus and yield stress of the blends. This is a consequence of the higher crystallinity of the blends in the presence of a higher amount of wax. The average tie chain concentration in the blends is estimated in order to explain detrimental effects of the wax on the ultimate properties. A significant correlation was found between stress and strain at break and the concentration of tie chains. Cross-linking improves the ultimate properties of the blends and pure polyethylene. On the other hand, because of its low molecular weight, thermal stability decreases with an increase in wax content and this trend remains unchanged after crosslinking.

Foliar damage to ornamental trees sprinkler-irrigated with reuse water

The extent of foliar damage to ornamental trees irrigated with treated sewage effluent (reuse water) may be a significant factor dictating the extent of reuse water implementation on golf courses, schools and parks in the arid southwestern United States. An experiment was conducted on 20 tree species to determine the extent of foliar damage when sprinkler-irrigated with reuse water, municipal water or a synthesized saline water. Irrigations (168) were applied over a 16-month period via 183-cm raised sprinkler heads, to plots that contained the trees in a dual-pot system. Plant water status, growth, tissue ion concentrations and an index of visual damage (IVD) were assessed at different times throughout the experiment. A higher IVD (greater foliar damage) was reported for most species when sprinkler-irrigated with either reuse or synthesized saline water. However, six species showed significant foliar damage even when irrigated with municipal water. The accumulation of Cl in the tissue was shown to be a species-dependent response, with tissue Cl concentrations varying by as much as a factor of 5. When a backward stepwise multiple regression analysis was conducted on the normalized (reuse-municipal) IVD and tissue ion concentrations, all ions except Na were eliminated from the correlation (Index (reuse – municipal)=0.79+0.62Na (reuse – municipal), r=0.72***, n=20). Wax content on the leaves in the reuse (0.310 mg cm–2) and saline treatments (0.546 mg cm–2) and the increase in wax content with time (young leaves/May vs mature leaves/July) suggested a possible stress response. Based on the results of this experiment, we believe the number of woody ornamental trees that can tolerate spray irrigation of reuse water in the hot dry environment of southern Nevada to be limited.