Amount Of Wax Research Articles

Elevated air humidity increases UV mediated leaf and DNA damage in pea (Pisum sativum) due to reduced flavonoid content and antioxidant power.

Growth in high relative air humidity (RH, >85%) affects plant morphology and causes diminished response to stomatal closing signals. Many greenhouses are prone to high RH conditions, which may negatively affect production and post-harvest quality. UV radiation induces stomatal closure in several species, and facilitates disease control. We hypothesised that UV exposure may trigger stomatal closure in pea plants (Pisum sativum) grown in high RH, thereby restoring stomatal function. The effects of UV exposure were tested on plants grown in moderate (60%) or high (90%) RH. UV exposure occurred at night, according to a disease control protocol. Lower stomatal conductance rates were found in UV-exposed plants, though UV exposure did not improve the rate of response to closing stimuli or desiccation tolerance. UV-exposed plants showed leaf curling, chlorosis, necrosis, and DNA damage measured by the presence of cyclobutane pyrimidine dimers (CPD), all of which were significantly greater in high RH plants. These plants also had lower total flavonoid content than moderate RH plants, and UV-exposed plants had less than controls. Plants exposed to UV had a higher content of cuticular layer uronic compounds than control plants. However, high RH plants had a higher relative amount of cuticular waxes, but decreased proteins and uronic compounds. Plants grown in high RH had reduced foliar antioxidant power compared to moderate RH. These results indicate that high RH plants were more susceptible to UV-induced damage than moderate RH plants due to reduced flavonoid content and oxidative stress defence.

Effects of different environmental conditions on the cognitive function of honeybee (Apis mellifera L.) and mineral content of honey

The aim of the present study was to determine the effect of local area inhabited by bee colonies on regional efficiency, foraging behavior and the content of certain metal elements in honey. Bee colonies from the same genetic source in different regions demonstrated significant variation (P<0.001) in behavior and performance. Initially, the number of forager worker bees exiting and entering the hive was approximately equal to each other. However, over time a significant difference (P<0.001) occurred between regions. Varying regional conditions caused considerable difference (P<0.001) in the average honey yields of colonies (between 28.60 ± 3.27 and 0.571 ± 2.76 kg/colony). Significant differences (P<0.01) in the amount of wax produced were also observed between regions. These regional differences were further reflected in concentrations of certain heavy metals in centrifugal honey samples. Environmental effects were determined to be the most important reason for the differences in all phenotypes, such as behavior, honey yield and heavy metal concentrations in honey. Those colonies inhabiting industrial or polluted areas died before the winter. Therefore, colonies are only productive when provided with appropriate environments or conditions.

DEVELOPMENT OF FREEZE DRIED SUGARCANE JUICE POWDER

Sugarcane juice is composed by 75 to 82% of water and 18 to 25% of soluble solids, which are constituted by sucrose, glucose, fructose, and lower amounts of amino acids, acids, waxes, fats, pigments, and inorganic salts. Due to its nutritional properties, sugarcane juice has shown potential to fulfill athletes’ energy needs. The aim of this work was to obtain sugarcane juice powder using freeze drying, perform the physicochemical characterization of the raw material and the powder obtained and to determine the powder solubility. The sugarcane juice in natura showed average soluble solid content of 17.71º Brix and ratio of 46.83; its average contents of calcium and magnesium were 33.94mg.100mL-1 and 10.82mg.100mL-1, respectively. The powder showed good solubility and satisfied the legislation requirements with respect to moisture. The water activity obtained (0.49) allowed inhibition of bacterial growth and significant reduction of chemical and enzymatic reactions, contributing to extend the shelf life of products.

Genotypic variation in leaf epicuticular wax quantity in a large faba bean (Vicia faba L.) germplasm collection

AbstractAmong grain legumes, faba bean is reputed to be relatively sensitive to drought stress. Epicuticular wax (ECW) quantity is considered as an important drought adaptation strategy in plant species. This study aimed to define variation in leaf ECW concentration as a drought-adaptive trait in 197 faba bean accessions under well-watered conditions. The relationship between ECW and stomatal characteristics was also investigated. Highly significant differences were found in the ECW concentration, which ranged from 0.680 to 2.104 mg/dm2. No relationships were found between ECW and any measure of stomatal morphology and function. This study provides evidence of the wide variation in ECW in faba bean germplasm, which is independent of stomatal characteristics and leaf water content. This variation may allow the genetic improvement of ECW as a drought-adaptive character in faba bean breeding programs aiming at the economical use of water.

A Comprehensive Critique on Wool Grease Extraction, Properties and Applications

The utilization of raw wool wax (grease) extracted from scouring effluent of fleece of sheep has been recognized two millennia ago. About seven centuries B.C., wool grease wax was extracted by Greek labors. Nowadays, tremendous amounts of wool wax are discharged each year into the scouring effluent of wool fleece. Restore of wool grease from textile effluent is of prime importance targeting environment protection. This article outlines the current and the possible ways of extraction of wool wax from coarse wool fleece; taking into consideration the economic and ecologic aspects. The methods of purification of the extracted wool grease into lanolin are also briefed. Recent techniques; namely microwave and ultrasonic-assisted extraction and purification of wool wax, were compared to the conventional heating method used for extraction of wool wax. Chemical and physical characteristics of the extracted lanolin, which play important role in its utilization, are outlined. The current and future utilization of wool wax in textile and non-textile application are reported.

X-ray microtomography to evaluate the efficacy of paraffin wax coating for soil bulk density evaluation

The paraffin-coated method is a well-used approach to measure the soil bulk density (BD). BD is a physical property of great importance for studies of soil quality and health. Therefore, representative measurements of this property are highly valued. Resin and paraffin wax are utilized to coat soil samples; however, if these materials ingress into the sample it could affect the representativeness of BD evaluation. The advance in three-dimensional (3D) image analysis techniques such as X-ray microtomography (μCT) offers a great opportunity to visualize and quantify the possible penetration of paraffin wax into clod samples. In this paper we investigated porous system morphological properties of soil samples coated with paraffin wax. The morphological properties of the pores filled with paraffin wax inside the samples were also studied. We observed qualitatively that samples with large pores close to their borders were more susceptible to the penetration of paraffin wax. Samples with pores >10 mm3 had the highest amount of paraffin wax into them. Triaxial shaped and complexly pores also offered less resistance to the ingress of paraffin wax. Positive relations between the amount of paraffin wax inside the samples and the volume of pores measured, pore tortuosity and degree of anisotropy were found. Conversely, the soil pore connectivity was not correlated with the penetration of paraffin wax into the samples, at least for the region of interest (≈27.3 cm3) studied. Finally, an analysis of the impact of paraffin wax ingress inside the samples in measured BD showed increments of ≈0.09 and ≈0.11 g cm−3 in this property when the paraffin wax penetrates into the large pores.

Evaluation of Wax Inhibitor Performance through Various Techniques

Various techniques were used to compare the effectiveness of a commercially available wax inhibitor (WIA) to a newly developed wax inhibitor (WIEP) using a highly waxy Wyoming crude oil—which causes plugging within wellbores and pipelines. The two additives were compared using centrifuge experiments, cold finger tests, and the precipitation and redissolution waxphaltene determinator (WD) method. Centrifuge tube experiments, and cold finger tests, showed that the newly developed WIEP additive was significantly more effective at reducing the amount of ambient temperature wax crystallites in the crude oil, as well as reducing the amount of wax deposited on a cold finger. WD analysis was performed on model compounds to differentiate between shorter and longer n-paraffins. Whole crude oils, ambient temperature waxes centrifuged from the oils, and waxes from cold finger deposits were also analyzed by the WD method. Taken together with high temperature gas chromatography, the WD profile of whole crude oils readi...

Chemometric differentiation of crude oil families in the southern Dongying Depression, Bohai Bay Basin, China

Fifty-seven crude oil samples from the southern Dongying Depression were selected for detailed geochemical analysis. High C26/C25 tricyclic terpanes (0.81–1.26) and low C31 homohopane (R)/C30 hopane (0.15–0.26) ratios indicate that the oils are from lacustrine source rocks. The presence of C30 4α-methyl-24-ethylcholestanes and C30 tetracyclic polyprenoids imply the contribution of microalgal organic matter. Large variations of depositional environment-related biomarker parameters suggest differences in organofacies and water environment. Four genetically distinct oil families were differentiated by chemometrics of hierarchical cluster and principal component analyses using the parameter dataset of three isotope ratios and 15 molecular parameters, all related to source and depositional environment. Family I is mature and does not match any available source rocks. The inferred source rock contains microalgal material that could produce large quantities of wax, C29 steranes and tricyclic terpenoids in a reducing, salinity stratified water column. Family II is characterized by a strong phytane dominance, relatively high gammacerane and C35 homohopanes, and low diasterane and 4-methyl sterane contents. It has high values of sterane/hopane (S/H = 1.67–4.14), C35/C34 homohopane (C35H/C34H = 0.81–1.66) and gammacerane/C30 hopane (G/C30H = 0.57–1.13) and low pristane/phytane (Pr/Ph = 0.30–0.59), suggesting that the inferred source rock is the upper Es4 interval. Family III has characteristics distinct from families I and II: low S/H (0.15–0.27), C35H/C34H (0.39–0.49) and G/C30H (0.03–0.12) ratios and high Pr/Ph (0.48–1.90), C30-4M/C29 ααα20R (0.54–1.18) and C30 tetracyclic polyprenoid (0.54–0.66) ratios, suggesting that the source rock is the lower Es3 interval. The family IV oils are compositionally in-between the ranges of families II and III oils, and in line with them in plots of geochemical parameters. We suggest that family IV consists of mixed oils derived from the upper Es4 and lower Es3 intervals. Family II has a relatively low thermal maturity and the inferred source rock may be located in the Niuzhuang Sag and/or the southern gentle slope zone. Family III is mature and its inferred source rock may be situated in the Lijin and Boxing sags. The upper Es4 and lower Es3 source rocks in the three sags contribute the crude oils of family IV that occurs in the middle and eastern parts of the southern Dongying Depression.

Viscoelastic and adhesion properties of hot-melts made with blends of ethylene-co-n-butyl acrylate (EBA) and ethylene-co-vinyl acetate (EVA) copolymers

Several hot-melts (HMAs) were prepared by using blends of ethylene-co-n-butyl acrylate (EBA) and ethylene-co-vinyl acetate (EVA) copolymers - EBA/EVA. HMAs were prepared with mixtures of EVA copolymers with 18 (EVA18) and 27 (EVA27) wt% vinyl acetate contents and EBA copolymer with 27 wt% n-butyl acrylate, polyterpene resin and mixture of microcrystalline and Fischer-Tropsch waxes. HMAs made with EBA/EVA blends showed lower viscosities and reduced shear thinning than the ones made with EBA or EVA due to differences in compatibility, but both the set time and the open time were not affected as they depended mainly on the wax nature and amount. The increase of the vinyl acetate (VA) content in EVA copolymer reduced the crystallinity of the EBA/EVA blends. Even EBA copolymer was more compatible with EVA27 than with EVA18 (the α- and β-transitions shown in DMTA plots were closer) and the compatibility did not vary with the EBA content in the blends. The addition of polyterpene resin and the mixture of waxes decreased the compatibility of the EBA/EVA blends, the higher compatibility was observed for the HMAs made with only one copolymer. The tack of the HMAs depended on their EBA/EVA contents, EBA/EVA27 HMAs showed broader temperature interval with higher tack, while the tack of EBA/EVA18 HMAs blend decreased and the temperature interval with tack was shortened and shifted to lower temperatures. Adhesion to polypropylene film was improved in HMAs made with 75 wt% EBA/25 wt% EVA18 and 50–75 wt% EBA/50-25 wt% EVA27. The adhesion to aluminum film of EBA or EVA hot melts was improved only in the joints made with EBA/EVA 27 HMAs, more noticeably when they contained higher EBA content.

Water-repellent plant surface structure induced by gall-forming insects for waste management.

Many animals and plants have evolved elaborate water-repellent microstructures on their surface, which often play important roles in their ecological adaptation. Here, we report a unique type of water-repellent structure on a plant surface, which develops as an insect-induced plant morphology in a social context. Some social aphids form galls on their host plant, in which they produce large amounts of hydrophobic wax. Excreted honeydew is coated by the powdery wax to form 'honeydew balls', which are actively disposed by soldier nymphs through an opening on their gall. These activities are enabled by a highly water-repellent inner gall surface, and we discovered that this surface is covered with dense trichomes that are not found on normal plant surfaces. The trichomes are coated by fine particles of the insect-produced wax, thereby realizing a high water repellency with a cooperative interaction between aphids and plants. The plant leaves on which the gall is formed often exhibit patchy areas with dense trichomes, representing an ectopic expression of the insect-induced plant morphology. In the pouch-shaped closed galls of a related social aphid species, by contrast, the inner surface was not covered with trichomes. Our findings provide a convincing example of how the extended phenotype of an animal, expressed in a plant, plays a pivotal role in maintaining sociality.

Overexpression of the ABC transporter gene TsABCG11 increases cuticle lipids and abiotic stress tolerance in Arabidopsis

The cuticle, composed primarily of wax and cutin, covers most plant aerial surfaces and plays a vital role in interactions between plants and their environment. Some ATP-binding cassette G subfamily (ABCG) members are involved in cuticular lipid molecule exportation to outside in the plant surface. Thellungiella salsugineum, a relative of Arabidopsis thaliana with a heavy cuticle, has extreme stress tolerance. TsABCG11, an ABCG transporter was cloned (GenBank accession number JQ389853), and its structure was studied. qRT-PCR showed that TsABCG11 expression varied in different organs of T. salsugineum and was upregulated under ABA, NaCl, drought and cold conditions. The rosette leaves from 4-week-old TsABCG11 overexpressed (OE) Arabidopsis plants displayed lower rates of water loss and decreased chlorophyll-extracted rates compared to wild-type plants. TsABCG11-OE plants also exhibited significantly increased total cuticular wax and cutin monomer amounts, mainly due to prominent changes in the C29, C31, and C33 alkanes in the wax and C18:2 dioic in cutin monomers, respectively. TsABCG11-OE seedlings exhibit lower root growth inhibition under 100 mM of NaCl or 1 µM of ABA than the wild type. Four-week-old TsABCG11-OE plants exhibited higher photosynthetic rates and water-use efficiency under cold stress (4 °C) than control plants. These results indicate that TsABCG11 plays an important role in cuticle lipid exportation and is involved in abiotic stresses, probably having a close relationship with extreme stress tolerance in T. salsugineum.

Reassessing Operational Strategies for Wax Management Reduces Expenses

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper OTC 27532, “The Importance of Periodic Reassessment of Operational Strategies for Wax Management,” by David M. Lavenson, SPE, Rama Venkatesan, SPE, Michelle K. Young, and Neal Kebert, Chevron, prepared for the 2017 Offshore Technology Conference, Houston, 1–4 May. The paper has not been peer reviewed. Copyright 2017 Offshore Technology Conference. Reproduced by permission. This paper presents a case study that is an example of how reassessing a flow-assurance risk-management strategy for operating assets can identify opportunities for optimization. Too often, flow-assurance risks are examined only after problems occur. In the absence of these events, many may assume the flow-assurance risks are managed optimally. Periodic reassessment of the risk-management strategies is a key concept for full life-cycle flow-assurance engineering. Introduction Flow-assurance risks for offshore fields can be managed in a variety of ways that can be defined generally into risk-management or risk-avoidance strategies. As offshore developments progress into deeper waters with more-challenging technical issues, more-costly risk-avoidance strategies can jeopardize overall project economics. In contrast, risk-management strategies are considered through means of mechanical, thermal, operational, or chemical adjustments to manage the flow-assurance risk rather than attempting to remove it entirely. Waxy crude oils are fairly common in offshore operations. As system temperatures drop below the wax appearance temperature (WAT), wax crystals will precipitate and cause deposition issues because of the thermal gradient between the bulk fluid and the pipe wall. A variety of mitigation techniques can reduce the effects of wax deposition on flowlines and pipelines offshore, including insulation, addition of heat, pigging, and the addition of paraffin inhibitors. In the development stages of a project, these risks are quantified by use of fluid properties and additional laboratory testing in order to estimate the required risk level and economic options for risk mitigation. The selected methods for managing the risk are used for first oil and adjusted and optimized while minimizing risk of compromising safe and reliable operations. Given the dependence of flow-assurance risks on various fluid and system properties, these risk-management strategies require periodic reassessment to ensure an optimized approach. This paper will present a case study where reassessment of a flow-assurance risk-management strategy resulted in an optimized approach that generated significant operational-expenditure savings. An offshore, brownfield development in West Africa has two subsea export pipelines that transport a medium-gravity waxy crude oil to an intermediate platform and eventually onshore. The crude in the export lines is from multiple wells and commingled, with each crude featuring varying amounts of wax, resulting in a combined oil that has a WAT ranging from 70 to 85°F. Ambient water conditions are less than 50°F, resulting in a temperature gradient across the fluid and pipe wall to the seawater. Because of the length of the export pipelines and lack of insulation, the oil cools to temperatures below the WAT well before the export line terminates at the intermediate platform.

The effect of pressure on wax deposition from wax-solvent mixtures with natural gas

Wax deposition occurs when the temperature of the pipe wall falls below the wax appearance temperature. This deposition reduces the effective flow area of the pipelines, leading to a significant pressure drop, which increases the transportation consumption and leads eventually to complete blockage. Most wax deposition studies have neglected the influence of natural gas, but natural gas is present in the actual pipelines and must be accounted for in field operations.A self-developed cold-finger apparatus was used to investigate the effects of pressure on wax deposition with natural gas (with 89.01% methane). The wax solvent mixtures consisted of a wax (C22–C37) dissolved in a paraffinic solvent (C11–C15). The wax deposition experiments were performed with 5, 7, and 10 mass percent wax solutions, for pressures ranging from 0.1 MPa to 6 MPa. The experimental results indicated that the maximum amount of wax is deposited at ordinary pressure. The amount of wax deposited increased at pressures ranging from 1 MPa to 2 MPa and decreased thereafter (at pressures ranging from 2 MPa to 6 MPa). In addition, the pressure corresponding to the maximum wax deposition varied with the wax content. Furthermore, the wax crystal morphology was observed using a polarizing microscope, and the morphology was quantitatively described via the fractal dimension. The analysis showed that the fractal dimension decreased with increasing pressure.This study confirms that natural gas plays a vital role in wax deposition studies, especially those aimed at predicting the wax deposition in actual pipelines, using a wax deposition model based on the laboratory experiments.

Effect of surfactants and leaf surface morphology on the evaporation time and coverage area of ZnIDHA droplets

The aim of the study was to determine the effects of the addition of surfactants to ZnIDHA fertilizer on the area of leaf coverage and water evaporation time taking into account the morphology of leaf blades. The effect of three surfactants (polyglucoside, alcohol EO (ethylene oxide) and trisiloxane) on the size of the leaf coverage area and evaporation time was compared. Adaxial leaf surfaces of maize (Zea mays L. `Wilga`), wheat (Triticum aestivum `Adana-99`) and rapeseed (Brassica napus L. `F1`) were analyzed by scanning electron microscopy and laser scanning confocal microscopy. The contact angle for aqueous ZnIDHA solutions with and without the addition of surfactants was determined. Measurements of droplet evaporation time and area of leaf coverage were conducted at the relative humidity of 60±1%. The adaxial surfaces of wheat and rapeseed leaves used in the study can be classified as highly non-wettable, whereas maize leaves are no-wettable. Out of the surfactants under study, the largest leaf coverage area was observed when adding the trisiloxane surfactant. Regardless of the surfactant used, the leaf coverage area decreased and the evaporation time increased for fertilizer droplets applied to the maize, rapeseed and wheat leaves. This study demonstrated that the addition of surfactants to the fertilizer solution increases the wettability of the adaxial leaf surface and induces a strong capillary effect which determines the direction of spread of fertilizer droplets. In addition to the amount of trichomes and waxes, also the capillary effect has a significant impact on water evaporation time and the area of leaf coverage by fertilizer droplets.

Extraction of rotenoids from Derris elliptica using supercritical CO2

AbstractBACKGROUNDSupercritical (SC)‐CO2 extraction of rotenoids from Derris elliptica roots was proposed using fractional separation of the extracts and operating at increasing pressure.RESULTSThe best processing conditions were found at 200 bar, 40 °C and 1.2 kg h−1 SC‐CO2 flow rate, obtaining a final product with a concentration of 93% w/w of rotenone and rotenoids, and a yield of active principles of 6.70% w/w with respect to the vegetable matrix. Very small quantities of waxes were found, up to 0.05% w/w; this result can be explained considering the reduced surface‐to‐volume ratio of this vegetable material.CONCLUSIONExtraction kinetics data confirmed that, in this case, the extraction process was controlled by solubility limitation of the active compounds in the supercritical solvent. © 2018 Society of Chemical Industry

Mode of Inheritance and Combining ability studies on Epicuticular wax Production in Resistance to Black pod disease in Cacao (Theobroma cacao L.)

Abstract Black pod caused by Phytophthora species is a devastating disease of cacao (Theobroma cacao L.) in production regions worldwide. Breeding for cacao genotypes resistant to black pod disease is crucial for sustainable cocoa production and profitability. Although breeding programmes in the past have made considerable efforts in improving resistance of cocoa genotypes with diverse genetic background, the disease continues to cause unacceptable yield losses in cacao production. To understand the mode of inheritance of epicuticular wax on the surface of cocoa pod known to play a major role in resistance to black pod disease, a 6 × 6 full diallel and a M x N (6 × 4) mating designs were used and data was analysed using Griffing’s method I model I approach and the North Carolina design –II approach, respectively. The results of the two mating designs were consistent and showed that epicuticular wax on leaf and pod surfaces of cacao were under the control of additive genetic effects. The non-additive effects were generally much smaller compared to the additive genetic effects. The significant association between GCA estimates of parents and their means indicates that parental values could be used as indicators of progeny performance. The best general combiners for epicuticular wax load on leaf and pod surfaces were Pa7/808, T60/887 and Pa 150. The larger additive components and heritability observed in this study, indicates that pedigree selection could be used to develop cacao cultivars with high amount of epicuticular wax on pod surface to enhance resistance to black pod disease.

OsABCG9 Is an Important ABC Transporter of Cuticular Wax Deposition in Rice.

The importance of the cuticular layer in regulating a plant’s water status and providing protection from environmental challenges has been recognized for a long time. The cuticular layer in plants restricts non-stomatal water loss and protects plants against damage from pathogen infection and UV radiation. Much genetic and biochemical research has been done about cutin and wax transportation in Arabidopsis thaliana, but little is known about it in rice. Here, we report that a rice ATP-binding cassette (ABC) transporter, OsABCG9, is essential for normal development during vegetative growth and could play a critical role in the transportation of epicuticular wax in rice. Rice phenotypes with mutated OsABCG9 exhibited growth retardation and sensitivity to low humidity. The total amount of cuticular wax on the leaves of the osabcg9-1 mutant diminished by 53% compared with the wild type, and wax crystals disappeared completely in osabcg9-2 mutant leaves. However, OsABCG9 does not seem to be involved in cutin transportation, even though its ortholog in Arabidopsis, AtABCG11, transports both wax and cutin. Furthermore, the osabcg9-1 mutant had increased leaf chlorophyll leaching and more severe drought susceptibility. This study provides new insights about differences between rice and A. thaliana in wax and cutin transportation associated with the ABCG family during evolution.

Stepwise pyrolysis of mixed plastics and paper for separation of oxygenated and hydrocarbon condensates

Mixed plastics and papers are two of the main fractions in municipal solid waste which is a critical environmental issue today. Recovering energy and chemicals from this waste stream by pyrolysis is one of the favorable options to achieve a circular economy. While pyrolysis products from plastics are mainly hydrocarbons, pyrolysis products from paper/biomass are highly oxygenated. The different nature of the two pyrolysis products results in different treatments and applications as well as economic values. Therefore, separation of these two products by multi-step pyrolysis based on their different decomposition temperatures could be beneficial for downstream processes to recover materials, chemicals and/or energy. In this work, stepwise pyrolysis of mixed plastics and paper waste was performed in a batch type fixed bed reactor using two different pyrolysis temperatures. Neat plastic materials (polystyrene, polyethylene) and cellulose mixtures were used as starting materials. Then, the same conditions were applied to a mixed plastics and paper residue stream derived from paper recycling process. The condensable products were analyzed by GC/MS. It was found that pyrolysis temperatures during the first and second step of 350 and 500 °C resulted in a better separation of the oxygenated and hydrocarbon condensates than when a lower pyrolysis temperature (300 °C) was used in the first step. The products from the first step were derived from cellulose with some heavy fraction of styrene oligomers, while the products from the second step were mainly hydrocarbons derived from polystyrene and polyethylene. This thus shows that stepwise pyrolysis can separate the products from these materials, although with some degree of overlapping products. Indications of interaction between PS and cellulose during stepwise pyrolysis were observed including an increase in char yield, a decrease in liquid yield from the first temperature step and changes in liquid composition, compared to stepwise pyrolysis of the two materials separately. A longer vapor residence time in the second step was found to help reducing the amount of wax derived from polyethylene. Results from stepwise pyrolysis of a real waste showed that oxygenated and acidic products were concentrated in the liquid from the first step, while the product from the second step contained a high portion of hydrocarbons and had a low acid number.

Structural laminated hybrid composites based on raffia and glass fibers: Effect of alkali treatment, mechanical and thermal properties

This work deals with the effect of the alkaline treatment of laminated hybrid composite materials based on Rafia fibers and glass fibers in sandwich structure. Structural analysis (Fourier Transform Infrared Spectroscopy) has shown that most of the changes caused by the alkaline treatment of Rafia fibers involve the removal of fiber surface from a certain amount of wax, hemicellulose, pectin and lignin. These changes are at the origin of the improvement of the mechanical properties of the composites. Flexural modulus results show an increase of 3.4 GPa–3.6 GPa for the untreated and treated Rafia fiber sandwich composites, respectively. The degree of interfacial adhesion quantified by a droplet test, shows that the alkaline modification reveals a sharp increase in shear stress for processed Rafia fibers with a 38% gain compared to untreated fibers. In addition, the measurement of the thermal conductivity has proved that the alkaline treatment decreases the thermal conductivity of the fibers. Finally, the mixing rule technique was used to predict the flexural modulus of the laminates using the mechanical parameters of each layer and the result was compared to the experimental data. It is assumed that Rafia fiber treatments will support the development of synthetic fiber reinforced sandwich polymer composites for industrial applications.

Efecto de los polímeros sobre las propiedades reológicas de los betunes céreos

The definition of bitumen wax has been formulated to facilitate the distinction between harmful wax and less harmful or non-harmful. Since exact behaviour of waxes within bitumens is not completely determined and the absence of cooperative study related to modification of bitumens involving different amounts of waxes, the values found in the study are thought to be useful in determining which content of wax and type of polymer would be better for the needs of petroleum refineries in different countries. The scope of this study is to minimize the negative effects of waxes within bitumens obtained from different sources. For this purpose, modified bitumen samples were prepared by using different types of polymers such as elastomers, plastomers and polyethylene groups. Following the determination of the contents of wax by Differential Scanning Calorimetry and TS EN 12606-1, rheological properties of waxy bitumens and polymer modified bitumens (PMB) were evaluated using dynamic shear rheometer tests. The intermediate temperature performance levels of PMB were also determined by fatigue parameters. Besides, rutting performance of PMB was evaluated using Zero Shear Viscosity and Multiple Stress Creep Recovery tests.