scholarly journals THE COMPATIBILITY OF MODEL FOR LOW SHEAR FLOW ANALYSIS IN DEVELOPING PLASTICIZED HTPB-BASED BINDER

2020 ◽  
Vol 5 (3) ◽  
pp. 189-200
Author(s):  
Afni Restasari ◽  
Luthfia Hajar Abdillah ◽  
Retno Ardianingsih ◽  
Bagus Wicaksono ◽  
Rika Suwana Budi
Keyword(s):  
Shear Rate ◽  
Flow Behavior ◽  
Flow Analysis ◽  
Equation Model ◽  
Liquid Content ◽  
Zero Shear Viscosity ◽  
Flow Behavior Index ◽  
Percentage Difference ◽  
Composite Solid Propellant ◽  
The Difference

In developing flow behavior of plasticized prepolymer as liquid content of composite solid propellant, zero shear viscosity (ZSV) is a critical parameter that Goh-Wan equation is developed to model it recently [1]. Thus, this work aims to analyze the compatibility of the Goh-Wan equation toward the liquid content of propellant, characterize it, and determine the limit. In this work, a varied flow behavior index was obtained by using Hydroxy terminated polybutadiene (HTPB) and HTPB-DOA (Dioctyl adipate) system with the variable of its concentration, pre-heating, and pre-stirring methods as samples. Viscosity was measured at 2, 3, 4, and 5 rpm by using the disc spindle of Brookfield viscometer. For the minimum shear-rate investigation, as a limit of compatibility, other three sets of shear rates are applied, which are 0.6 – 5 rpm, 1 – 5 rpm, and 1,5 – 5 rpm. By functioning Goh-Wan equation (model 1) and Power-Law (model 2), a model was categorized as compatible if yields lower value of ZSV than the first experimental measured viscosity (η1st). Characterization was determined by a graph of plotting percentage difference of ZSV obtained from models 1 and 2 towards the index of flow behavior. The 3% of the difference between ZSV obtained from model 1 and  η1st was set to be a minimum value for a set of applied shear-rate to be acceptable. It is reported that the Goh-Wan model is compatible with the liquid content of propellant and characterized by a perfect linear correlation. It is also found that a minimum applied shear rate of 1.5 rpm is acceptable for model compatibility.

Rheological Behavior of Seed Gum from Cassia fistula

2019 ◽  
Vol 818 ◽  
pp. 16-20
Author(s):  
Wancheng Sittikijyothin ◽  
Khanaphit Khumduang ◽  
Keonakhone Khounvilay ◽  
Rattanaphol Mongkholrattanasit
Keyword(s):  
Shear Rate ◽  
Flow Behavior ◽  
Critical Concentration ◽  
Shear Thinning ◽  
Zero Shear Viscosity ◽  
Specific Viscosity ◽  
Cross Model ◽  
Linear Slope ◽  
Mechanical Spectra ◽  
Seed Gum

The C. fistula gums in aqueous solutions clearly exhibited shear-thinning flow behavior at high shear rate, however, at higher concentrations, pronounced shear thinning was observed. The value of zero shear viscosity [h0] was predicted by fitting Cross model. A plotting of specific viscosity at zero shear rate (hsp0) against coil overlap parameter (C[h]) was shown the linear slope of dilute and simi-dilute as 1.43 and 4.10, respectively, which found the critical concentration (C*) about 7.08/[h]. While, the mechanical spectra in the linear viscoelastic region of gum solutions showed the typical shape for macromolecular solutions.

scholarly journals Rheological and functional properties of Roselle (Hibiscus sabdariffa) leaves puree

10.5219/929 ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 46-57
Author(s):  
Jaga Mohan Meher ◽  
Bidyut Mazumdar ◽  
Amit Keshav
Keyword(s):  
Experimental Data ◽  
Shear Rate ◽  
Flow Behavior ◽  
Hibiscus Sabdariffa ◽  
Temperature Level ◽  
Flow Behavior Index ◽  
Rheological Models ◽  
Rheological Analysis ◽  
Ir Analysis ◽  
Behavior Index

Pureed form of leaves (Hibiscus sabdariffa L. (Roselle)) was taken for physicochemical and rheological analysis at temperatures and TSS range of 278 K - 318 K and 3 - 5 °Brix respectively. The steady-state rheological analysis was performed with a shear rate of 1 - 100 s-1. Different rheological models are tried; Power-law was best fitted with the experimental data (R2 ≥0.98). Temperature dependence of viscosity was found out using an Arrhenius-type relationship at a shear rate of 10, 50, 100 s-1 IR analysis was done to know the influence of functional groups on rheological properties of purees. Consistency index (K) of puree increases with increase in TSS content but at a fixed TSS, there is a decrease in K with an increase in temperatures but the opposite was observed for flow behavior index (n). Puree showed a shear thinning behavior with an increment in temperature level and puree having 5 °Brix (8.37) has higher activation energy (kJ.mol-1) than 3 °Brix (6.32).  

scholarly journals Aqueous Solutions of Polyethoxylated Fatty Alcohols Rheological behavior and superficial properties

2019 ◽  
Vol 70 (2) ◽  
pp. 382-386
Author(s):  
Andra Tamas ◽  
Sabina Nitu
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Aqueous Solutions ◽  
Rheological Behavior ◽  
Flow Behavior ◽  
Fatty Alcohols ◽  
Flow Behavior Index ◽  
Foaming Power ◽  
Newtonian Behavior ◽  
Behavior Index

The paper presents the study of the rheological and superficial behavior (foaming power and wetting capacity) of some aqueous solutions with polyethoxylated fatty alcohols content. The influence of fatty alcohols concentration and their degree of ethoxylation as well as that of temperature on the rheological behavior was determined from the dependences between the shear stress t and the shear rate. The results demonstrate that all the studied solutions have non-Newtonian behavior, with flow behavior index smaller than 1.

An Influence of a Binder System to the Rheological Behavior of the SS316L Metal Injection Molding (MIM) Feedstock

2011 ◽  
Vol 264-265 ◽  
pp. 554-558 ◽  
Author(s):  
Khairur Rijal Jamaludin ◽  
Norhamidi Muhamad ◽  
Hooman Abolhasani ◽  
Hadi Murthadha ◽  
Mohd Nizam Ab. Rahman
Keyword(s):  
Activation Energy ◽  
Shear Rate ◽  
Injection Molding ◽  
Rheological Behavior ◽  
Flow Behavior ◽  
Palm Stearin ◽  
Metal Injection Molding ◽  
Binder System ◽  
Flow Behavior Index ◽  
Injection Molded

The influence of a binder system to the rheological behavior of a Metal Injection Molding (MIM) feedstock is presented in the paper. The binder systems used are: a) PEG & PMMA b) Palm stearin & LLDPE and, c) Tapioca starch & LLDPE. The viscosity and shear rate of the feedstocks were measured at various range of temperature and shear rate across the L/D = 10 capillary rheometer. The flow behavior index, n and activation energy, E of each feedstock were measured to show its significance as MIM feedstock. Generally, the result indicates all feedstock exhibits a shear thinning behavior and the binders are suitable as MIM binder. Additionally, the present paper has discovered that the binder system does not have much influence to the activation energy. In order to show the relevance of the rheological behavior to the actual injection molding performance, green parts has been injection molded and the result shows an agreement with the rheological behavior result.

Application of Modified Power Law and Arrhenius Relationship in Studying Rheological Behavior of Bio-Oils

2006 ◽  
Vol 517 ◽  
pp. 147-152 ◽  
Author(s):  
W.S. Wan Nik ◽  
S.G. Eng Giap ◽  
H.H. Masjuki ◽  
H.B. Senin
Keyword(s):  
Experimental Data ◽  
Shear Rate ◽  
Power Law ◽  
Corn Oil ◽  
Flow Behavior ◽  
Type Equation ◽  
Power Law Model ◽  
Flow Behavior Index ◽  
Different Temperatures ◽  
Modified Power Law

Tribological aspects of bio-oils have to be investigated before they are used as industrial fluids. In this paper rheological (fluid deformation under shear) properties of four bio-oils are presented. A Couette type viscometer was used to evaluate flow behavior of the oils at seven discrete temperatures. Commercial coconut, canola, sunflower and corn oil were used in this study. For all the oil samples, viscosities were affected by the change of shear rate and temperature. Two rheological models, temperature dependence and shear rate dependence, were used in the study. The original power law gives contradict picture of flow curves and flow parameters. Thus, modified power law model was proposed. The modified model was fitted to experimental data to obtain the flow behavior index. Arrhenius type equation was fitted to experimental data to obtain the activation energy due to different temperatures and shear rates. Evaluation of rheological properties by modified power law model indicates that these bio-oils belong to the pseudo-plastic group.

scholarly journals Rheological Properties of Cassava Starch Film Forming Solution with Kaffir Lime Oil

2019 ◽  
Vol 8 (4) ◽  
pp. 6781-6786
Keyword(s):  
Shear Rate ◽  
Rheological Properties ◽  
Flow Behavior ◽  
Cassava Starch ◽  
Food Preservation ◽  
Effect Of Temperature ◽  
Flow Behavior Index ◽  
Film Forming ◽  
Biopolymer Film

Biopolymer film has attracted interest in food preservation and packaging. In order to obtain biopolymer film of good characteristics, rheological properties of film forming solution is important. In this study, the rheological properties of cassava starch film forming solution incorporated with kaffir lime oil were determined. The flow behavior measurement was made at shear rate of 0.1 to 100 s -1 and 25 C, whereas the effect of temperature on viscosity was measured at 25 to 70 C and shear rate of 10 s-1 . The flow behavior was well described by power law or Ostwald de Waele model. The film forming solution showed flow behavior index (n) in the range of 0.20 to 0.72 which belonged to a non-Newtonian or pseudoplastic behavior. The shear stress increased with increasing shear rate and temperature. The dependency of temperature on viscosity was described by Arrhenius model which allowed the determination of activation energy (Ea ). The Ea of the film forming solutions range between 4.92 to 13.23 kJ mol-1 . The rheological properties obtained in this study provide a basis to correlate the film forming solution properties to the characteristics of the produced biopolymer film.

Effects of Greek Pomegranate Extracts in the Antioxidant Properties and Storage Stability of Kefir

2019 ◽  
Vol 15 (4) ◽  
pp. 437-441 ◽  
Author(s):  
Vasiliki Lagouri ◽  
Georgia Dimitreli ◽  
Aikatarini Kouvatsi
Keyword(s):  
Antioxidant Activity ◽  
Dairy Products ◽  
Storage Time ◽  
Storage Stability ◽  
Flow Behavior ◽  
Antioxidant Properties ◽  
Flow Behavior Index ◽  
Ph Values ◽  
Dpph Activity ◽  
Behavior Index

Background: Oxidation reactions are known to shorten the shelf life and cause damage to foods rich in fat, such as dairy products. One way to limit oxidation and increase the shelf life of fermented dairy products is to use natural antioxidants. The aim of this study was to examine the effect of adding pomegranate extracts in the antioxidant properties, rheological characteristics and the storage stability of the fermented product of kefir. Methods: The Pomegranate Juice (PGJ) and Peel Extracts (PGPE) (5%, 10% w/v) were added to kefir and the antioxidant properties were evaluated by using the methods of radical scavenging activity (DPPH) and Ferric Reducing Antioxidant Power Activity (FRAP). Spectrophotometric and instrumental methods were used to determine the Total Phenols (TPs), pH values, viscosity and flow behavioral index values of enriched with pomegranate kefir samples. The same properties were tested when kefir samples stored at 4°C for 7, 14, 21 and 28 days. Results: The addition of PGJ and PGPE results in an increase in the antioxidant activity (DPPH, FRAP) and total phenol content (TPs) of kefir samples. Increasing the concentration of the added PGJ and PGPE, results in an increase in the TP content and the DPPH activity of kefir. As far as the storage time is concerned, the results showed an increase in the amount of TP at 7th day and a reduction in the DPPH activity in the 14th day of storage. In contrary to the DPPH method, the increase in storage time has resulted in a reduction in antioxidant activity by the FRAP method. The addition of PGJ and PGPE in kefir results in a decrease in pH values while the pH of kefir samples increased during storage at 4°C for 28 days. The addition of PGJ and PGPE to kefir samples results to a decrease in viscosity and an increase in the flow behavior index. Increasing storage time results in increased flow behavior index of kefir samples. Conclusion: The addition of PGJ and PGPE increased the antioxidant activity and total phenols of the kefir product and preserved its properties during the total storage time of 28 days at 4°C.

scholarly journals Numerical Simulation of Effect of Different Initial Morphologies on Melt Hydrodynamics in Laser Polishing of Ti6Al4V

Micromachines ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 581
Author(s):  
Kai Li ◽  
Zhenyu Zhao ◽  
Houming Zhou ◽  
Hao Zhou ◽  
Jie Yin ◽  
...  
Keyword(s):  
Flow Behavior ◽  
Processing Parameters ◽  
Surface Finishing ◽  
Polished Surface ◽  
Laser Polishing ◽  
Starting Position ◽  
Double Spiral ◽  
The Difference ◽  
Thermocapillary Forces ◽  
Surface Morphologies

As a surface finishing technique for rapid remelting and re-solidification, laser polishing can effectively eliminate the asperities so as to approach the feature size. Nevertheless, the polished surface quality is significantly sensitive to the processing parameters, especially with respect to melt hydrodynamics. In this paper, a transient two-dimensional model was developed to demonstrate the molten flow behavior for different surface morphologies of the Ti6Al4V alloy. It is illustrated that the complex evolution of the melt hydrodynamics involving heat conduction, thermal convection, thermal radiation, melting and solidification during laser polishing. Results show that the uniformity of the distribution of surface peaks and valleys can improve the molten flow stability and obtain better smoothing effect. The high cooling rate of the molten pool resulting in a shortening of the molten lifetime, which prevents the peaks from being removed by capillary and thermocapillary forces. It is revealed that the mechanism of secondary roughness formation on polished surface. Moreover, the double spiral nest Marangoni convection extrudes the molten to the outsides. It results in the formation of expansion and depression, corresponding to nearby the starting position and at the edges of the polished surface. It is further found that the difference between the simulation and experimental depression depths is only about 2 μm. Correspondingly, the errors are approximately 8.3%, 14.3% and 13.3%, corresponding to Models 1, 2 and 3, respectively. The aforementioned results illustrated that the predicted surface profiles agree reasonably well with the experimentally measured surface height data.

Curved Exponential Models in Econometrics

1997 ◽  
Vol 13 (6) ◽  
pp. 771-790 ◽  
Author(s):  
Kees Jan van Garderen
Keyword(s):  
Structural Equation ◽  
Equation Model ◽  
Econometric Models ◽  
Demand Systems ◽  
Likelihood Ratios ◽  
Sufficient Statistics ◽  
Sufficient Statistic ◽  
Exponential Models ◽  
Minimal Sufficient Statistic ◽  
The Difference

Curved exponential models have the property that the dimension of the minimal sufficient statistic is larger than the number of parameters in the model. Many econometric models share this feature. The first part of the paper shows that, in fact, econometric models with this property are necessarily curved exponential. A method for constructing an explicit set of minimal sufficient statistics, based on partial scores and likelihood ratios, is given. The difference in dimension between parameterand statistic and the curvature of these models have important consequences for inference. It is not the purpose of this paper to contribute significantly to the theory of curved exponential models, other than to show that the theory applies to many econometric models and to highlight some multivariate aspects. Using the methods developed in the first part, we show that demand systems, the single structural equation model, the seemingly unrelated regressions, and autoregressive models are all curved exponential models.

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