Papers by Keyword: Rheological

Abstract: This article summarizes the investigation results of the rheological and thermal stability properties of industrially prepared wood plastic composites based on virgin polypropylene (PP) and birch plywood production waste product, plywood sanding dust (PSD). Wood plastic composites (WPCs) PP+40 wt.% PSD contain different modifiers, such as functional lubricant Struktol TWP, antioxidant 1010, thermal stabilizer 168, ultraviolet (UV) stabilizer 770, and pigment concentrate based on low density polyethylene (LDPE). According to these studies, it was concluded that rheological properties studied by the capillary rheometry method depend on WPC composition and the parameters of rheological measurements. On the contrary, melt flow index (MFI) values did not change so much and fluctuated in the range of 1.52–1.66 g/10 min. The presence of thermal and antioxidant stabilizers promoted an increase in the thermal stability of WPCs, as determined by the thermal gravimetric analysis (TGA) method. The characteristics of fluidity curves indicated the character of typical pseudo-plastic liquids, in which viscosity not only depends on temperature, shear stress, and shear deformation rate but also decreases with an increase in shear deformation rate. That also confirmed the values of the fluidity index (n), which for pseudo-plastic polymer melts are always smaller than 1.

Abstract: Recently, sustainable green binders became mandatory for the construction industry. The process of cement production is responsible for a considerable portion of CO₂ causing global warming. Clinker substitution using available by-products is one of the promising strategies to cut down the CO₂ emissions of the cement industry. Yet, it is challenging to limit the emission of CO₂ without negatively affecting the strength and durability of the proposed concrete. One of the proposed green binders is Limestone-Calcined Clay cement (LC3). The newly developed LC3 binder integrates the advantages of incorporating available cement replacement materials - clay and limestone – and attaining adequate mechanical, physical, and durability performance. In this paper, an intensive review of previous research in LC3-based construction materials including nanomodification, fiber reinforcement, and durability enhancement is presented in details, aiming to highlight the points that lack investigation and the recommended future work.

Abstract: The influence of the main structure-forming oxides Li₂O/Al₂O₃, SiO₂/Al₂O₃ and H₂O/Al₂O₃ on the physical, rheological and colloidal-chemical properties of lithium-containing alumosilicate suspensions xLi₂O-Al₂O₃-nSiO₂-mH₂O in the system are presented for the first time. As a result of optimization, the optimal area of influence of variable factors was determined for the ratio of oxides Li₂O/Al₂O₃ from 0.82 to 1.05 mol, SiO₂/Al₂O₃ from 3.4 to 4.5 mol and H₂O/Al₂O₃ from 19 to 21.5 mol, providing normative levels of properties of lithium-containing alumosilicate suspensions, namely: density from 1.4 to 1.521 g/cm³, process viscosity from 15 to 47 sec, pH from 11.15 to 11.34, surface tension from 51.4 to 60.4 mN/m, cosine of the substrate contact angle from 0, 57 to 0.91, work of adhesion forces from 97 to 116 mN/m, work of cohesion forces from 103 to 121 mN/m, work of wetting forces from 27 to 52 mN/m, wetting coefficient from 0.78 to 0.96, spreading coefficient from –5 to –20 mN/m. The data obtained will form the basis for the creation of protective materials of new generation that, in the event of emergencies, can provide both the protection of people and technological equipment, buildings and constructions.

Abstract: In the present work, the effect of temperature on calcium carbonate precipitation in the biomimetic calcium chloride solution was investigated. A spontaneous calcium carbonate precipitate was formed in the biomimetic calcium chloride solution as a result of the carbon dioxide hydration process. The reaction was conducted at different temperature range vary from 30°C to 100°C. The mass of the calcium carbonate precipitate and the pH solution was measured in the study. The finding indicated that an increment of the temperature has led to the fast pH reduction of the solutions to 7.0. However, the process has retarded the calcium carbonate precipitation process. The optimum temperature for higher calcium carbonate precipitation has occurred at the temperature range of 47.5°C – 65°C which gave the highest calcium carbonate precipitate at 0.121g. The addition of Tris buffer into the calcium chloride solution in this study did not gave an inhibition effect on the calcium carbonate precipitate. Based on the results, an operating condition at 47.5°C – 65°C was recommended to be used in mineral carbonization of CO₂ using the biomimetic calcium chloride solution.

Abstract: To this day, there is a large volume collected of the results of experimental studies on structure changes in various dispersions serving as base for production of most construction materials. The analysis of collected information revealed that there is an entire category of stick-slip phenomena, the case history of which is represented by N-and S-type inflections on rheological, kinetic and other curves. We should emphasis that the view of such non-trivial charts is alike with geometry of standard curves of standard conditions. And this alikeness predetermines the possibility of applying topological models of «fold» and «ruffle» types for studying various abnormal effects. We must also note that besides N- and S-types there is a range of other characteristics («flags») pointing to applicability of the methods of catastrophe theory to studying certain processes initiating the apparition of interruptions in system development. Recognition of above-mentioned particularities allows determining the fact and type of catastrophe, the standardised structure of which facilitates finding strict patterns and thus defines directions of optimisation of various situations of research and practical nature. This work shows that pieces of evidence and consistent patters are reliably interpreted within the framework of the proposed concept.

Abstract: Palm kernel shells (PKS) filled recycled high density polyethylene (rHDPE) biocomposites were produced using melt mixing. The biocomposites were prepared on Brabender Plasticorder at temperature of 185 °C and rotor speed of 50 rpm by varying filler loading (0 to 40 phr). In this study, the effect of PKS loading on rheological properties and thermal stability of rHDPE/PKS were investigated. Rheological study of the biocomposites was carried out by means of capillary rheometer under temperature of 190 °C, 200 °C and 210 °C. Thermal properties of biocomposites were studied by using thermo gravimetric analysis (TGA). The rheological results showed that the flowability of the composite increased with increasing temperature. Meanwhile, the result of TGA showed that at higher PKS loading, rHDPE/PKS biocomposites had lower total weight loss. The thermal stability of the biocomposites was reduced due to the addition of filler loading.

Abstract: The performances of PP/MMT nanocomposite (70μm thick films), in terms of thermal and rheological properties were investigated. A twin-screw extruder was used to compound PP, MMT, compatibilizer, and extruded nanocomposite films were collected for test. All results were compared and the influence of MMT contents on the final properties were observed and reported. The thermal properties of PP had improved by increasing MMT content from 0-3 phr. However at 4 phr thermal stability of the nanocomposite had slightly dropped. In terms of rhelogical properties, the addition of MMT to the PP blend increased the complex viscosity of the nanocomposites, particularly at low frequency regions.

Abstract: In this work, the rheological behavior of uncured natural rubber with different initial moisture contents dried by microwave was studied using RPA under frequency sweep and strain sweep modes. It can be seen from the results that the variation trend of viscous torque S`` versus sweep frequency kept with the trend of elastic torque S` versus sweep frequency. Moreover, the viscous torque S`` values were lower than those for elastic torque S`, a good linear relation curve was obtained by plotting elastic torque S` versus sweep frequency. The curve of storage shear modulus G` versus sweep strain presented a linear relationship, showed a linear viscoelastic behavior of uncured natural rubber with different initial moisture contents. This may be explained by the degradation of molecular chains of natural rubber and the van der waals forces between them.

Abstract: Abst r a c t -Magneto rheological aqueous is an old advancing to the bazaar at top speed. Excellent appearance like fast response, simple interface amid electrical ability ascribe and automated ability output, and absolute controllability accomplish MRF technology adorable for abounding applications.The aim of this project is preparation of MR-fluids by using the different types of carrier fluid mixed with iron powder and stability and magnetic properties are analysed. Thesedimentation of iron particles can be reduced by using additives. The sedimentation can be analysed by boundary variation of the clear fluid to the fluid turbulence. The viscosity of smart fluid can be increased by varying the applied magnetic field.The performance of the MR-damper depends on the applied maximum magnetic field and the hydraulic circuit design. The MR-damper force by increasing the magnetic field can be analysed by sing the FEMM V4 Software.Damping force depends on the excitation of current and magnetic field.Key words: Rheological, magnetic field, damping force, FEMM, flux density

Abstract: In drilling and well completion operations, drilling fluid is a crucial element as it is employed for the purposes of several functions. The main functions of drilling fluid are to control formation pressure, maintain the wellbore stability, transport the cuttings up to surface to clean the borehole bottom as well as to lubricate and cool the drill bit. Moreover, it is used to minimize the drilling damage to reservoir and suspend cuttings when the pumping is stop, hence it will not falling back down the borehole. The purpose of this study is to formulate new drilling mud formulation modified with nanosilica. Six samples of water based mud (WBM) were prepared using three types of polymers, (Xanthan Gum, Hydro Zan Plus and Hydro Star HT), starch and nanosilica. Basic rheological tests such as density, viscosity and pH were carried out. The density test was carried out using mud balance meanwhile the pH test was using pH meter. The plastic viscosity, yield point and gel strength tests were carried out using viscometer. Besides that, physical observation was also performed for as the stability test. The results concluded that water based mud incorporated with polymer Hydro Zan Plus and nanosilica can be a potential candidate to be commercialized as a smart nanodrilling fluid.