Dynamic Rheometer Research Articles

Bacterial Blocking and Repair of Intestinal Defects With Well-Alighed Lamellar MXene/Polyvinyl Alcohol Hydrogels Prepared by Bidirectional Freezing Method

To explore the bacterial blocking effect of oriented multilayer MXene/polyvinyl alcohol (PVA) nanocomposite hydrogels and their effect on the repair of intestinal defects. MXene/PVA nanocomposite hydrogels were prepared using the traditional freezing method and the bidirectional freezing ice template method. The structures of the different hydrogels were observed using scanning electron microscopy (SEM) and micro-CT reconstruction. The rheological properties of the hydrogels were measured using a dynamic rheometer, and their mechanical properties were assessed using a universal testing machine. The burst pressure of the hydrogels was determined through burst experiments, and bacterial colony growth was observed by the osmosis method to assess the bacteria blocking ability of the hydrogels in vitro. A rat model of cecal perforation was established, and the hydrogels were used for intestinal repair. Gram staining was performed to observe in vivo the bacterial blocking ability of the hydrogels, HE staining was performed to observe the intestinal inflammation, and CD31 and CD68 immunofluorescence staining and proliferating cell nuclear antigen (PCNA) staining were performed to observe the repair effect of the hydrogels on intestinal defects. SEM and micro-CT reconstruction revealed that the hydrogel prepared by the traditional freezing method exhibited a random porous structure, while the hydrogel prepared by the bidirectional freezing method showed an oriented multilayer structure. Rheological and tensile tests indicated that the oriented hydrogel had superior mechanical properties, and the burst pressure of the oriented multilayer hydrogel was as high as 27 kPa, significantly higher than that of the non-oriented hydrogel (P<0.001). Bacterial colony growth was observed by the osmosis method and it was found that, compared with the non-oriented hydrogel, the oriented multilayer hydrogel could effectively prevent the infiltration of Escherichia coli and Staphylococcus aureus in vitro. Gram staining results showed that the oriented multilayer hydrogel could effectively block intestinal bacteria from entering the abdominal cavity in vivo. HE staining results showed that the oriented multilayer hydrogel could effectively reduce intestinal inflammation in vivo. CD31 and CD68 immunofluorescence staining and PCNA staining results showed that the oriented multilayer hydrogel had a repairing effect on intestinal defects in vivo. The oriented multilayer hydrogel prepared by bidirectional freezing effectively prevents bacterial infiltration and reduces intestinal inflammation.

Preparation and properties of thermoplastic starch under the synergism of ultrasonic and elongational rheology

Thermoplastic starch, as an eco-friendly alternative to petroleum-based plastics, possesses numerous advantages, including cost-effectiveness, complete biodegradability, and renewable sourcing. Nevertheless, the plasticizer dispersion and starch plasticization efficiency are poor via the processing method dominate by shear deformation. Thus, the aim of this study is proposing a new approach combining ultrasonic treatment and elongational rheology to prepare thermoplastic starch and evaluate its properties. This innovative approach facilitated the production of thermoplastic starch with glycerol as the plasticizer at varying rotor speeds. Furthermore, this study was carried out by using a self-developed ultrasonic-assisted vane mixer (UVM) based on elongational flow. The samples were analyzed using FTIR, WAXD, polarized optical microscope, dynamic rheometer, universal testing machine and thermogravimetric analysis. FTIR and dynamic rheological analysis showed that elongational rheology and ultrasonics stimulate hydrogen bond formation between starch and glycerol, elevating starch thermoplasticity. Tensile tests and thermogravimetric analysis highlighted that high-intensity elongational field improved the mechanical properties and thermal stability of the thermoplastic starch. Additionally, the incorporation of ultrasonic treatment yielded further improvements, yielding remarkable tensile strength (6.09 MPa) and elongation at break (139.3 %). This synergistic interplay between ultrasonics and elongational rheology holds immense potential for advancing thermoplastic starch manufacturing.

Breadmaking Quality Parameters of Different Varieties of Triticale Cultivars.

The aim of this research is to investigate the quality of different triticale cultivars (Ingen 35, Ingen 33, Ingen 93, Ingen 54, Ingen 40, Fanica and Costel) cultivated in the Republic of Moldova from the point of view of the flour, dough, and bread quality characteristics. This research may be of great importance for producers and consumers due to the high production capacity, wide adaptability, economic significance in human foods and nutritional value of triticale cultivars. The triticale flours were analyzed for moisture, ash, protein, wet gluten, fat, carbohydrates, acidity and color parameters (L*, a* and b* values). According to the chemical values, the triticale flours were suitable for breadmaking. The moisture content was less than 14% for all triticale varieties, indicating a long shelf life during its storage and the lowest protein content of 13.1%. The mixing, pasting and fermentation characteristics of triticale dough were analyzed using Mixolab, falling number, dynamic rheometer, alveograph and rheofermentometer devices. All triticale flours presented high levels of α-amylase, with falling number values being less than 70 s. The bread quality characteristics analyzed were the loaf volume, porosity, acidity, and sensory characteristics, and the textural parameters examined were the hardness, gumminess, chewiness, cohesiveness, and resilience. Our data showed large differences in breadmaking quality parameters. However, according to the sensory data, all the bread samples except those obtained from the Costel variety were of a very good quality, being within a total sensory range of 25.26-29.85 points. According to the relationships between flour, dough and bread characteristics obtained through principal component analysis, it may be concluded that the triticale varieties Costel, Ingen 33, Ingen 93 and Fanica, and Ingen 35 were more closely associated with each other. Significant differences were found between the triticale variety samples Ingen 40, Fanica, and Ingen 35 and between Ingen 54, Ingen 33, Costel, and Ingen 93.

Improvement of oxidized myofibrillar protein gel properties by black rice extract

In order to investigate the effects of black rice extract (BE) on the composition of oxidized myofibrillar protein (MP) gel, different concentrations of BE (0, 10, 20, 50 mg g−1) were analyzed experimentally. Results revealed that the addition of small doses of BE significantly inhibited the formation of carbonyl groups in oxidized MP, and improved surface hydrophobicity and gel water holding capacity. Additionally, 10 and 20 mg g−1 BE increased the ordered structure of oxidized MP. Furthermore, dynamic rheometer results showed a significant increase in the storage modulus (G') of oxidized MP with 10 and 20 mg g−1 BE during heating. Scanning Electron Microscopy (SEM) showed that MP formed a denser network structure with addition of 10 and 20 mg g−1 BE. Low-Field Nuclear Magnetic Resonance (LF-NMR) and magnetic resonance imaging (MRI) showed that there is a significant increase in immobile water in MP gel and a decrease in free water within the 20 mg g−1 BE group. In conclusion, 20 mg g−1 supplemented BE significantly improved the structure order and hardness of oxidized MP gel, increased its structure density and water holding capacity, and it provides a theoretical basis for the application of antioxidants in meat products.

Hybrid Paneer: Influence of mung bean protein isolate (Vigna radiata L.) on the texture, microstructure, and in vitro gastro-small intestinal digestion

Replacing dairy proteins with legume proteins such as mung bean protein can create hybrid cheese alternatives with superior nutritional and functional properties. The effects of partially replacing (30%) cow milk with mung bean protein isolate (MBPI) on the rheology, texture, microstructure, and digestibility of paneer (acid-heat coagulated cheese) were studied. The developed hybrid cow milk-mung bean paneer (CMMBP) had higher protein and moisture contents, lower fat content, and a darker colour than cow milk paneer (CMP). CMMBP showed a significant reduction in hardness, cohesiveness, chewiness, and springiness compared to the cow milk-based control. Frequency sweeps performed using a dynamic rheometer showed higher storage modulus (G′) for CMMBP compared to CMP, indicating greater elastic properties of the hybrid paneer. In vitro digestibility of CMMBP was significantly lower than CMP, as shown by the lower overall ninhydrin-reactive free amino N release and the presence of resistant peptides at the end of digestion.

Fabricating super tough polylactic acid based composites by interfacial compatibilization of imidazolium polyurethane modified carbon nanotubes

The interfacial compatibilization and dispersion of carbon nanotubes (CNTs) in incompatible poly(lactic acid)/poly(butylene terephthalate adipate) (PLA/PBAT) composites are key points for evaluating the performance of the composites. To address this, a novel compatibilizer, sulfonate imidazolium polyurethane (IPU) containing PLA and poly(1,4-butylene adipate) segments modified CNTs, employed in conjunction with multi-component epoxy chain extender (ADR) to toughen synergistically PLA/PBAT composites. The thermal stability, rheological behavior, morphology, and mechanical properties of PLA/PBAT composites were performed by TGA, DSC, dynamic rheometer, SEM, tensile, and notched Izod impact measure. Moreover, the elongation at break and notched Izod impact strength of PLA5/PBAT5/4C/0.4I composites achieved 341 % and 61.8 kJ/m2 respectively, whose tensile strength was 33.7 MPa. The interfacial compatibilization and adhesion were enhanced because of the interface reaction catalyzed by IPU and the refined co-continuous phase structure. The CNTs non-covalently modified by IPU that bridged at the PBAT phase and interface transferred the stress into the matrix, prevented the development of microcracks, and absorbed impact fracture energy in the form of pull-out of the matrix, inducing shear yielding and plastic deformation. This new type of compatibilizer with modified CNTs is of great significance for realizing the high performance of PLA/PBAT composites.

Change of network structure in agarose solution during gelation studied by multiple particle tracking and NMR measurements

The gelation mechanism of agarose solution on cooling has been successfully elucidated by measurements from macroscopic to microscopic scales using a dynamic rheometer, the multiple particle tracking with two different diameters and the pulsed-field-gradient stimulated echo (PGSTE) 1H NMR. The dynamic rheometer detected the gradual increase of G’ in the temperature range from 55 to 40 °C before the steep increase at the gelation temperature. The time-averaged mean square displacement (msd) obtained by multiple particle tracking for particles with diameter of 270 nm and 1000 nm revealed the generation of micro domains with the network structure obstructing particle diffusion. Further, the NMR measurements gave detailed information about the change of molecular mobility for agarose chains during the formation of the micro domains and the macroscopic overall network structure. These results suggest a gelation mechanism and gel network structure including the formation of micro domains in the temperature range from 55 to 40 °C and the connection among the micro domains by agarose aggregates to form the overall network structure at the gelation temperature.

Effects of polyphenols on the gel and digestive properties of Penaeus vannamei myosin after freezing.

Polyphenols could inhibit the freezing-induced denaturation of myosin, and affect its nutritional and functional properties, which have rarely been studied to date. Therefore, the effects of interactions between polyphenols and myosin after freezing on myosin gel and digestive properties were investigated using low field NMR, a texture analyzer, a dynamic rheometer, ultraviolet-visible spectra, scanning electron microscopy, LC-MS/MS, an automatic amino acid analyzer, etc. Hesperetin (HE), dihydroquercetin (DI), salidroside (SA), and mangiferin (MA) increased the water-holding capacity, non-flowable water content, gel strength, texture, storage modulus, and fractal dimensions of the myosin gel, while modifying its leading force. The results of scanning electron microscopy revealed that the surfaces of polyphenol groups were relatively smoother than those of the control group. Meanwhile, the four types of polyphenols under study significantly improved the gastric and gastrointestinal digestibility of myosin. Furthermore, they significantly increased the contents of essential, flavor, and total free amino acids, as well as the unique peptide numbers in myosin digestion products. This work provides reliable guidance for polyphenols to improve protein function and nutritional properties.

Effect of fermented cream with partial substitution of soy protein isolate on bread quality and volatile compounds

This study aimed to improve the bread quality, especially aroma, using the fermented cream-soy protein isolate (SPI) flavor and reveal the improvement mechanisms. The cream with partially substituted SPI was fermented by lactic acid bacteria to enhance its flavor and used for bread making. The study also explored the positive effect of fermented cream on bread quality, especially the aroma formation. The bread quality was assessed by sensory evaluation, texture, and color determination, and the changes in bread dough characteristics were evaluated using a rheofermentometer and a dynamic rheometer. Furthermore, the influence of fermented cream-SPI flavor on bread volatile compounds (VOCs) was investigated using gas chromatography–mass spectrometry and principal component analysis. The results showed that the fermented cream-SPI flavor improved the texture of bread by increasing the gas production and the gluten strength of the dough. It reduced the crumb hardness from 337 ± 12 g to 171 ± 6 g and increased the specific volume from 3.51 ± 0.05 g/mL to 4.19 ± 0.06 g/mL. Moreover, the cream-SPI flavor improved the bread aroma by providing VOCs directly (acids, 2-nonanone, 2-undecanone, 2-tridecanone, and δ-dodecalactone) or precursor substances for VOC formation [esters, (E,E)-2,4-nonadienal, (E)-2-nonenal, and 1-octen-3-ol] during the bread-making process. The present study suggested that the partial substitution of SPI in cream after fermentation had great potential as a bread quality improver to enhance both the texture and aroma of bread.

Preparation and characterization of Perilla essential oil composite microcapsule based on the complex coacervation and interface polymerization.

In this paper, we prepared a novel double-layer Perilla essential oil composite membrane microcapsule (PEOCM) by the composite methods of complex coacervation and interface polymerization. The particle size distribution, morphology, pressure resistance, thermal stability, and elemental proportions of the microcapsule shell of the obtained microcapsules were characterized by laser particle size analyzer, scanning electron microscopy (SEM), dynamic rheometer, thermogravimetric analysis (TGA), and energy spectrometer. In order to further examine the application effect of the PEOCM, we carried out a fresh-keeping experiment on nectarines. The results showed that the average volume diameter of the microcapsules was 226.9µm, with a completely spherical shape and a slight depression on the surface and had good pressure resistance and thermal stability. The results also demonstrated that microencapsulation does not change the composition of Perilla essential oil, and the polyurea membrane with amide structure (-NH-CO-NH-) was formed successfully. Furthermore, the total soluble solids content and peroxidase activity of nectarines indicated that the PEOCM can be a preservative of food. PRACTICAL APPLICATION: We prepared a double-layer Perilla essential oil composite membrane microcapsule by the composite methods of complex coacervation and interface polymerization. The encapsulation conditions of the microcapsules were optimized, the structure of the microcapsule was characterized, and the fresh-keeping effects of the microcapsule on nectarine were studied. The results showed that microcapsules had a completely spherical shape and a slight depression on the surface and had good pressure resistance, good thermal stability, and good fresh-keeping ability. The above characteristics indicated that the double-layer microcapsules have good application prospect and plays an important role in food fresh-keeping and the preservation of essential oils.

Effect of PAN fiber with bionic layered surface structure generated in situ by Fenton reaction on performance of SBS/RP asphalt binder

• Innovative application of Fenton reaction in the modification of polyacrylonitrile fibers. • Biomimetic multi-layered structure modified polyacrylonitrile fibers. • KF-PAN/SBS/RP modified asphalt had better viscoelastic performance. • KF-PAN/SBS/RP modified asphalt had better low temperature anti-cracking performance, high temperature stability and fatigue damage resistance. • KF-PAN/SBS/RP modified asphalt had better rutting resistance and high temperature adhesion performance. In this study, a surface modified polyacrylonitrile fiber (KF-PAN) with a fish-scale whisker-like biomimetic hierarchical structure was successfully prepared via in situ competition effect of Fenton reaction. The modified fibers were used as secondary modifiers to prepare fiber-reinforced styrene–butadienestyrene (SBS) block copolymers and rubber powder (RP) modified asphalt binders (KF-PAN/SBS/RP). Energy dispersive spectroscopy, scanning electron microscopy, and atomic force microscopy analyses revealed the successful construction of bionic hierarchy on the fiber surface, and confirmed rough surface of the KF-PAN fibers. The hierarchical structure of the fiber surface acted as a buffer in the asphalt and strengthened the mutual interaction of the fiber and asphalt. Dynamic rheometer shear and strip-tensile tests showed that the KF-PAN/SBS/RP modified asphalt exhibited better viscoelasticity, rutting resistance, and tensile properties than the PAN/SBS/RP modified asphalt. The linear amplitude sweep test showed that KF-PAN/SBS/RP modified asphalt had better fatigue resistance. Thermogravimetric analysis tests indicated that the surface bionic structure of KF-PAN fibers boosted thermal stability of the fibers, which in turn enhanced the thermal stability of KF-PAN/SBS/RP modified asphalt. Fluorescence microscopy analysis showed that incorporating KF-PAN fibers improved the SBS and RP microstructure inside the asphalt, forming a good mesh structure, and alleviating the stress concentration phenomenon in SBS/RP asphalt under external traffic load.

The Influence of Temperature on Rheological Properties of Three Root Canal Sealers

Purpose was to determine the viscoelastic properties of three root canal sealers as a function of temperature, time and frequency using dynamic oscillatory measurements. Methods: Measurements were performed on the dynamic oscillatory rheometer set to temperatures: 25�C, 35�C, 40�C and 65�C. Stress sweep and frequency sweep tests were used in order to determine storage moduli G�, loss moduli G�� and complex viscosity η*. Results Higher values of storage compared to loss moduli indicate the more pronounced solid-like behavior of tested materials. EndoREZ showed the highest values of G� and G�� moduli at all temperatures. With temperature increase the G� and G�� moduli of Sealapex and EndoREZ increased while the moduli of AH Plus decreased. With frequency increase all materials showed viscosity decrease exhibiting non-Newtonion, shear-thinning behavior. With temperature increase AH Plus demonstrated viscosity decrease, while the viscosity of Sealapex and EndoREZ increased. Clinical significance: All tested materials were temperature, time and frequency dependent and this dependency varied between them. The obtained results may be used to predict the rheological behavior of root canal sealers in different temperature conditions, thus helping as to estimate optimal handling characteristics for specific clinical applications.

Preventing the browning of fresh wet noodle sheets by aqueous ozone mixing: Browning and physicochemical properties

The formation and prevention mechanism of the dark spots in fresh wet noodle sheets (FWNS) has been discussed in our previous study, while the factors which cause FWNS browning are very complicated. In this work, the browning of FWNS was prevented through aqueous ozone mixing. Meanwhile, low field nuclear magnetic resonance (LF-NMR), size-exclusion high-performance liquid chromatography (SE-HPLC), dynamic rheometer, and scanning electron microscope (SEM) were used to measure the physicochemical properties and microstructure of the FWNS. The relationship between browning and the physicochemical properties was discussed. The results showed that aqueous ozone mixing improved the color of FWNS, in which physical factors and non-covalent bonds played a key role. The results of the LF-NMR tests showed that aqueous ozone mixing reduced the moisture degree of freedom. The results of the SE-HPLC tests showed that the moderate oxidizing capability of aqueous ozone promoted the cross-linking of disulfide bonds in FWNS. The results of the dynamic rheology tests and SEM observation showed that aqueous ozone mixing strengthened the gluten network structure of FWNS. Thus, aqueous ozone mixing made FWNS more compact and uniform, and indirectly reduced the browning rate.

Effect of Cactus (Opuntia ficus-indica) and Acacia (Acacia seyal) Gums on the Pasting, Thermal, Textural, and Rheological Properties of Corn, Sweet Potato, and Turkish Bean Starches.

This study was planned to explore the locally available natural sources of gum hydrocolloids as a natural modifier of different starch properties. Corn (CS), sweet potato (SPS), and Turkish bean (TBS) starches were mixed with locally extracted native or acetylated cactus (CG) and acacia (AG) gums at 2 and 5% replacement levels. The binary mixtures (starch–gums) were prepared in water, freeze dried, ground to powder, and stored airtight. A rapid viscoanalyzer (RVA), differential scanning calorimeter (DSC), texture analyzer, and dynamic rheometer were used to explore their pasting, thermal, textural, and rheological properties. The presence of acetylated AG or CG increased the final viscosity (FV) in all three starches when compared to starch pastes containing native gums. Plain SPS dispersion had a higher pasting temperature (PT) than CS and TBS. The addition of AG or CG increased the PT of CS, SPS, and TBS. The thermograms revealed the overall enthalpy change of the starch and gum blends: TBS > SPS > CS. The peak temperature (Tp) of starches increased with increasing gum concentration from 2 to 5% for both AG and CG native and modified gums. When compared to the control gels, the addition of 2% CG, either native or modified, reduced the syneresis of starch gels. However, further addition (5% CG) increased the gels’ syneresis. Furthermore, the syneresis for the first cycle on the fourth day was higher than the second cycle on the eighth day for all starches. The addition of native and acetylated CG reduced the hardness of starch gels at all concentrations tested. All of the starch dispersions had higher G′ than G″ values, indicating that they were more elastic and less viscous with or without the gums. The apparent viscosity of all starch gels decreased as shear was increased, with profiles indicating time-dependent thixotropic behavior. All of the starch gels, with or without gums, showed a non-Newtonian shear thinning trend in the shear stress vs. shear rate graphs. The addition of acetylated CG gum to CS resulted in a higher activation energy (Ea) than the native counterparts and the control. More specifically, starch gels with a higher gum concentration (5%) provided greater Ea than their native counterparts.

Features of Bread Made from Different Amaranth Flour Fractions Partially Substituting Wheat Flour

Amaranth flour (AF) is recognized as high-quality raw material regarding nutrients and bioactive compounds, essential in supplying human health benefits, compared with white flour (WF). In this study, the effects of factors, different particles sizes (large, medium, and small), and levels of AF (5, 10, 15, and 20%) substituting WF on the responses, empirical and dynamic dough rheological properties, and some quality parameters of bread were successfully modeled using predictive models. Finally, the optimization of a formulation to maximize the AF level whilst maintaining bread quality for each type of particle size (PS) was performed based on the response surface methodology models generated. The rheological properties of the composite flour formulated were evaluated using Mixolab, alveograph, rheofermentometer, and dynamic rheometer. In addition, bread quality parameters, loaf volume, instrumental texture features, and firmness were evaluated. The anticipation of the optimal value for each response in terms of dough rheological properties during mixing, protein weakening, starch gelatinization and retrogradation, biaxial extension, fermentation, viscoelastic moduli, and creep and recovery compliance depending on PS. The optimal addition level was determined by a multi-objective optimization approach. The optimal addition level was 9.41% for large, 9.39% for medium, and 7.89% for small PS. The results can help manufacturers to develop bread products with the desired particle size with optimal technological and physical features.

Effect of elongational rheology on plasticization and properties of thermoplastic starch prepared by biaxial eccentric rotor extruder

Large amounts of plasticizers were added into natural starch for thermoplastic to make it processable due to the high crystallinity and large amount of intermolecular hydrogen bonds of starch. However, the traditional screw extruders based on shear deformation cannot disperse the plasticizer evenly and plasticize the starch well, which affects the comprehensive mechanical properties. In this paper, a self-developed biaxial eccentric rotor extruder (BERE) based on elongational rheology was introduced to prepare thermoplastic starch (TPS) sheets with glycerol as plasticizer at different speeds. The TPS sheets extruded by BERE all have excellent mechanical properties and optical transparency. Scanning electron microscopy, Fourier transformation infrared spectroscopy, X-ray diffraction, dynamic rheometer and universal mechanical tester were used to reveal the morphology, type and strength of hydrogen bonds, crystal structure, dynamic rheological and mechanical properties of TPS to research the effect of elongational rheology on its plasticization and properties. The results showed that the elongational rheology produced during processing process of BERE could obviously promote the dispersion of glycerol in starch and improve the melt-plasticizing effect of TPS, and the comprehensive mechanical properties of the TPS prepared by BERE is excellent with the elongation at break of 226.1%.

Insights into the mechanism on Glucono-delta-lactone induced gelation of soybean protein at subunit level

To elucidate the gelation process and gel properties of coagulation in soybean protein at subunit level, the dispersions of subunits (αα′- and β-subunit) of β-conglycinin and polypeptides (acidic and basic polypeptides) of glycinin were coagulated by Glucono-delta-lactone (GDL), and the gelation processes were monitored with a dynamic rheometer. The rheological properties, microstructure, water distribution, and secondary structure of the gels were determined as well. The results showed that the β-subunit and basic polypeptide coagulated faster, while αα′-subunit and acidic polypeptide developed firmer and finer gels, who had stronger ability of water holding and contained higher content of β-sheet structure. The GDL-induced subunits/polypeptides gel network were dominated by hydrophobic interactions and disulfide bonds. It is proposed that the mechanism on gelation of soybean protein at subunit level as: with acidification of GDL, the basic polypeptide and β-subunit initially aggregate and form a proto-gel matrix. Subsequently, with the developing of gelation, α- and α′-subunits, especially acidic polypeptide, who is the last one to coagulate, complements to form finer and firmer network, and finally grows together to a mature gel. Besides the gelation rate, the higher content of β-sheet secondary structure and better water holding ability of acidic polypeptide and αα′-subunits would also contribute to the firmness of gel. The elucidation of the gelation mechanism at subunit level would support innovation of gelling technique and benefit the soybean industry.

Physicochemical Characterization of Zirconia Nanoparticle-Based Sodium Alginate Polymer Suspension for Enhanced Oil Recovery

Biopolymers have been employed in enhanced oil recovery (EOR) due to their high viscosity and significant effects on waterflooding performance. Sodium alginate (NaAlg) is an excellent biopolymer that is extracted primarily from brown algae. It has been used in the biotechnology industry as a thickening agent, colloidal stabilizer, and oil recovery application. In the present study, a series of sodium alginate/zirconium oxide nanoparticle suspensions were prepared via solution mixing, and the effect of nanoparticle content, polymer concentration, temperature, salinity was investigated on the rheological behavior using a concentric cylinder dynamic rheometer. The rheology results revealed that the lower concentration of sodium alginates (0.01 to 0.06 wt %) and sodium alginate/nanoparticle suspensions (0.02 to 0.06 wt %) displayed shear thinning behavior for the whole range of shear rate from 0.1 to 100 s–1. It was noticed that the aging of the polymer/nanoparticle suspension at 25 °C for 7 days did not significantly affect the rheological characteristics. It was moreover observed that enhancing salinity from 0.015 to 0.1 wt % in the 0.04 wt % ZrO2 nanoparticle suspension comprising 0.1 wt % sodium alginate showed a progressive decrease in viscosity under the temperature range from 25 to 50 °C. The proposed sodium alginate/zirconium oxide nanoparticles from the mentioned results indicate their potential for enhanced oil recovery applications.

Evaluation of Carbon Nanotubes Asphalt Modification Using the Superpave Criteria

Rutting, fatigue cracking and low temperature cracking are the most important distresses in asphalt pavements as a result of changes in rheological properties of asphalt binder. Many types of modifiers were used to enhance asphalt behavior at both low and high temperatures. In this study, carbon nanotubes (CNT) were used as one of many nanomaterials that take a large attention in the latest research related to asphalt modification against different types of distresses. Effect of CNT on rheological properties of asphalt binder was investigated by testing unmodified and CNT modified asphalt binders using two of Superpave devices: Dynamic Shear Rheometer (DSR) and Bending Beam Rheometer (BBR). Penetration, softening point, flash point and rotational viscosity (RV) tests were carried out as well. CNT was added in 0.1%, 0.5% and 1% by weight of asphalt binder. It was found that adding CNT in 0.5% and 1% increase stiffness of asphalt and consequently asphalt pavement rutting resistance. On the other hand, this increase in stiffness affected pavement behavior adversely which is not desirable for fatigue and low temperature cracking. However, Superpave specifications were still satisfied and asphalt binder’s relaxation properties were improved upon CNT modification. It was eventually found that 0.5% of CNT is the optimum percentage for the best performance.

Properties of biomass powders resulting from the fine comminution of lignocellulosic feedstocks by three types of ball-mill set-up

Background: Lignocellulosic biomass has many functionalities that hold huge potential for material, energy or chemistry applications. To support advanced applications, the biomass must be milled into ultrafine powder to increase reactivity. This milling unit operation needs to be fully mastered to deliver high-quality standard end-products. Here we studied the relationship between the characteristics of the starting lignocellulosic plant material and the properties of the resulting ultrafine powder in different ball-mill process routes. Methods: Two lignocellulosic biomasses (pine bark and wheat straw) with contrasted compositional and mechanical properties were milled using three ball-mill set-ups delivering different balances of impact force and attrition force. The resulting powders were analysed for particle characteristics (size, agglomeration extent, shape) and powder flow properties (compressibility, cohesion) using a dynamic powder rheometer. Results: Pine bark is more amenable to a fast particle size reduction than the fibrous wheat straw. The resulting pine bark powders appear less compressible but much more cohesive than the straw powders due to particle shape, density and composition factors. The mill set-up working by attrition as dominant mechanical force (vibratory ball mill) produced a mix of large, elongated particles and higher amounts of fines as it acts mainly by erosion, the resulting powder being more prone to agglomerate due to the abundance of fines. The mill set-up working by impact as dominant mechanical force (rotary ball mill) produced more evenly distributed particle sizes and shapes. The resulting powder is less prone to agglomerate due to a preferential fragmentation mechanism. Conclusions: The attrition-dominant mill yields powders with dispersed particle sizes and shapes and the poorest flow properties, while the impact-dominant mill yields more agglomeration-prone powders. The mill set-up working with impact and attrition as concomitant mechanical forces (stirred ball mill) produces powders with better reactivity and flow properties compared to rotary and vibratory mills.