Structural, mechanical, thermal, and electrical properties of low‐loaded (0−1.5 wt%), untreated, and treated (with heat and nitric acid) multiwalled carbon nanotubes (MWCNTs)/poly (lactic acid) (PLA) nanocomposites have been studied. Among all synthesized composites, acid‐treated 1.0 wt% MWCNTs reinforced PLA shows superior tensile strength and modulus to those shown by other samples. All nanocomposites including the pure PLA exhibit the orthorhombic β‐form crystalline structure with low degree of crystallization, as demonstrated by X‐ray diffraction study. Differential scanning calorimetry (DSC) of injection molded samples, respectively, reveals an enhancement of PLA crystallinity by 8% and 14% for untreated and treated nanotubes, relating to the observed improvement in mechanical properties. Nanocomposites show double melting behavior when crystallized nonisothermally by DSC, whilst the pure PLA shows single melting character. Thermogravimetric analysis discloses that the MWCNTs‐loaded sample degraded faster than PLA. Surface resistivity of the nanocomposites is found to be dropped drastically by a factor of 1013 with a low loading of MWCNTs (1.5 wt%). A detailed discussion and correlation of the observed structures and properties are presented in this study. POLYM. ENG. SCI., 54:317–326, 2014. © 2013 Society of Plastics Engineers
This study numerically investigates Magnetohydrodynamic (MHD) convective and chemically reactive unsteady micropolar fluid flow with nanoparticles through the vertical porous plate with mass diffusion, thermal radiation, radiation absorption and heat source. A flow model is established by employing the well-known boundary layer approximations. To obtain the nonsimilar equation, the boundary layer governing equations including continuity, momentum, energy and concentration balance were nondimensionalised by usual transformation. A nonsimilar approach is applied to the flow model. To optimize the parametric values, the stability and convergence analysis (SCA) have been analysed for the Prandtl number (Pr) and Lewis number (Le). It is observed that with initial boundary conditions, U =V =T = C= 0 and for Δτ = 0.005, ΔX = 0.20 and ΔY = 0.25, the system converged at Prandtl number, Pr ≥ 0.356 and Lewis number, Le ≥ 0.16. The coupled non-linear partial differential equations are solved by explicit finite difference method (EFDM) and the numerical results have been calculated by Compaq Visual FORTRAN 6.6a. Evaluation of the thermal and momentum boundary layer thickness with isotherms and streamlines analysis of boundary layer flows have been shown for the thermal radiation parameter (R). The effects of various parameters entering the problem on velocity, angular velocity, temperature and concentration are shown graphically.
This article presents a comparative analysis of the properties of cotton yarn spun on aerodynamic compact spinning and open-end rotor spinning systems. Yarn samples with a linear density of 50 Tex, 37 Tex, 30 Tex, 25 Tex, and 20 Tex were spun both on the aerodynamic compact and rotor spinning systems using the same finisher drawn sliver of medium staple cotton which were produced by a specific mixing. The quality parameters such as mass variation, imperfection index, hairiness, and tensile behavior (strength in count strength product, elongation percentage) of the yarn samples were assessed and analyzed. The results revealed that aerodynamic compact spun yarn had a lower unevenness and mass variation, a higher imperfection in case of a finer count, less hairiness, higher tensile strength, and lower elonga-tion% compared to the open-end rotor spun yarn samples. Finally, pairedsamples t-test and regression analysis were carried out by using IBM SPSS 25 to check the significance of yarn quality parameters and correlation among them.
SPE Members Abstract A new mechanism of fluid flow in solution-gas drive heavy oil reservoirs is identified through experimental studies. This paper presents experimental results in order to verify previous hypothesis on fluid flow in heavy oil reservoirs in Canada. It has been postulated that solution-gas drive in these reservoirs involves simultaneous flow of gas and oil. However, gas remains in tiny droplets under reservoir conditions. A new mathematical model was proposed in order to describe peculiar pressure-dependent multiphase flow properties. peculiar pressure-dependent multiphase flow properties. This paper presents experimental validation of some of the hypotheses offered by Smith. More than 40 experimental tests are performed both in a capillary tube and in a core packed with unconsolidated reservoir fluids and sands. The effects of decreasing bubble size on total fluid production and pressure drop across a pipe are observed. Experiments with live oil and reservoir sands enable one to quantify the contribution of bubble flow in solution gas drive process involved in heavy oil reservoirs. Some of these results help explaining the anomalies observed in heavy oil reservoirs in Canada. Introduction Elkins et al hypothesized the existence of 'worm hole' porosity in the unconsolidated Sands held together only porosity in the unconsolidated Sands held together only by the viscous oil. This hypothesis has often been supported by sudden collapse in injection schemes or failure of drilling and workover operations in heavy oil reservoirs of the Lloydminster area. This concept has often been used to introduce a negative skin factors in modelling heavy oil reservoirs. While this technique has given satisfactory results in several occasions, the technique has been criticized to be scientifically inaccurate. In fact, Islam and George have demonstrated through laboratory experimentation that sand redistribution or even sand/fines removal would actually decrease the near wellbore permeability. Smith suggested that solution gas drive in Canadian heavy oil reservoirs involves simultaneous flow of many oil and tiny gas bubbles. He proposed a new model for predicting performance of heavy oil reservoirs in Canada. predicting performance of heavy oil reservoirs in Canada. Kennedy and Olson studied bubbles of methane in kerosene in the presence of silica and calcite crystals. They observed that bubbles formed on silica or calcite surfaces rather than in the oil medium itself. They found that the number of bubbles formed for a given volume of reservoir rock depends on the rate of diffusion of gas through oil and on the rate of pressure declined in the reservoir. One of their important observations was that the variation in gas distribution may lead to different relative permeabilities for the same gas saturation in the reservoir. In an effort to explain discrepancy between laboratory and field observations, Stewart et al. conducted a series of solution gas drive tests in limestone cores. They observed that the oil recovery depends directly on the number of bubbles produced. The number of bubbles, in turn, depends on the rate of decline of pressure. Since, usually laboratory tests are performed at a pressure decline which is much higher than that in the pressure decline which is much higher than that in the field, laboratory tests consistently lead to higher recovery performance. performance. Hunt and Berry presented both experimental and theoretical studies in order to determine the probability function of bubble nucleation time. They found that the mean rate of bubble formation increases rapidly with increasing supersaturation. They presented a theory for predicting bubble size as well as bubble concentration for a given rate of pressure decline. Wieland and Kennedy re-confirmed some of the previous observations. The found that a definite previous observations. The found that a definite supersaturation ranging from 14 to 25 psi can be imposed without forming any bubble. This range depended on the type of rock and fluid used. P. 495
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.