bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rheological Properties of Carbon Fiber and Carbon Black Filled Liquid Crystalline Polymer Melts
Authors: Araki Katsuhiko , Kitano Takeshi , Hausnerova Berenika 
Published: May 2019

Abstract
The rheological properties of thermotropic liquid crystalline polymer (LCP) and its carbon fiber (CF) and carbon black (CB) filled composites in molten state were measured using a cone-plate rheometer. The measurements of the CF/LCP and CB/LCP melts were performed with carbon fiber contents of 5, 10 and 20 wt %, and carbon black contents of 1.5, 3, 5, 10 and 20 wt %. As expected, steady shear viscosity of the LCP, CF/LCP and CB/LCP melts in a low shear rate region (0.1 to 1 s-1) decreased with an increase of temperature and increased with rise of filler content. In shear rate region of 1 to 50 s-1, the LCP melt showed a unique viscosity behaviour with maximum and minimum values. The CF/LCP and CB/LCP melts showed disappearance of such a unique viscosity behaviour with an increase in the CF (CB) content and an increase of temperature. CB filler had a more pronounced effect on the disappearance of the unique viscosity behaviour in comparison with CF. Regarding apparent yield stress, the CF/LCP melts gave the same value as pure LCP, the CB/LCP melts showed an increase of yield with a rise of the filler content. In addition, the first normal stress difference of the LCP and CF/LCP melts are smaller than yield stress values, although the rate of increase with shear rate is higher in case of normal stress difference than in case of yield. The results of the dynamic shear oscillatory flow measurements of CF and CB based compounds at 300˚C showed that both, the storage and loss moduli are more affected by carbon black filler. Complex viscosity values of the LCP and CF/LCP melts showed no such unique complex flow pattern as observed in the case of steady shear viscosity.
New Rheological Test Method to Determine the Dewatering Kinetics of Suspensions
Authors: Wollny Klaus 
Published: May 2019

Abstract
Rheology plays an important role in dewatering processes. It is therefore interesting to analyze the dewatering process and the rheological behavior of a suspension simultaneously. An exact determination of the immobilization point at the maximum of the loss factor as well as the immobilization time can be attained using an oscillatory time test with preset strain. The degree of dewatering is determined via normal force controlled gap setting. This report offers an insight into the theory of the dewatering of liquid supersaturated suspensions and shows how the kinetics of dewatering can be determined using paper coating as an example.
Rheological properties of suspensions with spherical particles in shear and elongational flows
Authors: Schmidt Michael 
Published: May 2019

Abstract
The rheological behaviour of model suspensions with spherical particles was experimentally investigated in shear an elongational flows. Particular attention was focussed on the main parameters affecting the flow behaviour of suspensions such as particle size distribution, particle size, particle surface, humidity, temperature and viscosity of the matrix fluids. All variables were investigated depending on the pre-shear conditions. In this regard the validity of the time-temperature-superposition and the Trouton-ratio was verified for suspensions with spherical particles.
Non-Newtonian Fluid Flow Analysis with Finite Difference and Finite Volume Numerical Models
Authors: Marn Jure , Delic Marjan , Zunic Zoran 
Published: May 2019

Abstract
Suitability of finite difference method and finite volume method for computation of incompressible non newtonian flow is analyzed. In addition, accuracy of numerical results depending of mesh size is assessed. Both methods are tested for driven cavity and compared to each other, to results from available literature and to results obtained using commercial code CFX 4.3.
Experimental and Numerical Investigation Into Metallocene Polymer Melt Flow in Film Blowing Dies
Authors: Zatloukal M. , Vlcek J. , Slaník A. , Lengálová A. , Simoník J. 
Published: May 2019

Abstract
A frequent problem in the production of metallocene linear low-density polyethylene (mLLDPE) films is the occur-rence of flow instabilities, e.g. sharkskin, or degradation of material, which limit the production rate and decrease the product quality. If such problems arise, the question is what causes these phenomena and how they can be avoided. With the aim of understanding these problems and providing some guidelines for their suppression, rheological measurements together with modelling of these melt flows are often employed. In the present study, flow behaviour of two commercially available mLLDPEs was determined and used for the process simulation. The paper shows that the capillary-rheology data together with 2D finite element method can be used for the prediction of sharkskin phenomenon as well as degradation of mLLDPE melts in film blowing dies. It also reveals that the degradation of the materials in these dies can be quantified through wall shear stress. Finally, the paper describes how these findings can help optimize the flow channel in the film blowing die to avoid the undesirable flow phenomena.
Rheological Properties and Shear Induced Texture Development of Thermotopic Liquid Crystalline Polymer Melts
Authors: Nguyen T.N. , Geiger K. , Fritz H.-G. 
Published: May 2019

AbstractThe flow behavior of two commercial liquid crystalline polymers (LCPs), trade name Vectra B 950 and Vectra L 950 supplied by Ticona, was investigated using a capillary rheometer with a special double slit die. The pressure drops in convergent and divergent wedge passage between the two slit sections, which are influenced by the curvature strains in nematic melts, were determined and compared with the pressure drops of a conventional polystyrene (PS) with flexible polymer chains. Furthermore the extensional viscositiy was determined from the pressure drop in convergent wedge passage. The development of the shear induced texture as a function of shear rate was investigated by use of a rapidly coolable double slit die with the same gap design as the double slit die used for viscosity measurement. The structural analysis was performed using polarized light microscopy.
Modeling the Pressure Decay Curve of a Capillary Rheometer
Authors: Warley Russ 
Published: May 2019

Abstract
A mathematical model for the transient pressure response in a capillary rheometer is implemented and validated with experimental data for both a natural rubber compound and a silicone rubber compound. The pressure decay curve after the cessation of motion of the instrument piston is shown to be consistent with the extrapolation of the power law model to shear rates two decades lower than experimentally attainable in the instrument employed. The model is useful for extending the range of the instrument in question by approximating material properties at shear rates lower than attainable in a steady flow experiment.
Characterisation of an Industrial Polymer Melt Through Either Uniaxial Extension or Exponential Shear Data: An Application of the Pom-Pom Model
Authors: Suneel  , Graham Richard S. , McLeish Tom C.B. 
Published: May 2019

Abstract
We present new non-linear data in extension and two different shear histories. These data are used to compare the effectiveness of using exponential shear data and uniaxial extension data to characterise the non-linear response of an industrial LDPE melt with the pom-pom molecular model. We conclude that extension and exponential shear both allow good predictions to be made in simple shear. However, the characterisation spectrum obtained from exponential shear data fails to predict the correct degree of strain hardening at low extension rates. From this study we are able to suggest circumstances under which exponential shear provides a useful characterisation of branched polymer melts.
Rheological Properties of a Natural Estuarine Mud
Authors: Aubry Thierry , Razafinimaro Tolotrahasiina , Jacinto Ricardo Silva , Bassoulet Philippe 
Published: May 2019

Abstract
In this paper, the linear and non-linear rheological properties of estuarine cohesive sediments were investigated. The density of the sediments has been determined by pycnometry. Creep and oscillatory shear measurements have been performed in order to determine i) the transitions in mechanical response to creep and oscillatory shear and ii) the material properties of these natural fluids as a function of their density. For all samples tested, four different rheological transitions have been determined and all material properties have been shown to be satisfactorily fitted by exponential functions of the density.
An Evaluation of Single-Segment Reptation Theories for Linear Entangled Polymeric Systems
Authors: Gigras Piyush G. , Khomami Bamin 
Published: May 2019

Abstract
A short synopsis of the recently proposed reptation models based on the Doi and Edwards’ tube concept is provided. Specifically, a critical examination of a number of theories like the “simplified” Mead-Larson-Doi model, the Öttinger model and the “Double Convection Reptation” model of Marrucci and coworkers has been performed. These models have been chosen due the fact that are computationally tractable as they mimic the chain dynamics in the tube using unconnected portions of the chain in a mean field way. Overall, we find each of these models to be equally competitive barring a few exceptional cases, where it is suspected that certain critical assumptions, made during the formulation of the model could lead to inaccurate predictions under transient or Lagrangian unsteady settings.
Rheological Properties of the Reverse Mesophases of the Pluronic L64/P-Xylene/Water System
Authors: Coppola Luigi , Gabriele Domenico , Nicotera Isabella , Oliviero Cesare 
Published: May 2019

Abstract
The behaviour of reverse micellar solution and reverse hexagonal and lamellar liquid crystal phases in pluronic L64/water/p-xylene ternary system was investigated by rheological techniques. Samples with an increasing water content along the amphiphilic copolymer-lean side of the ternary phase diagram were analysed at different temperatures and a different behaviour was evidenced by both dynamic and steady tests for each considered phase, depending on the morphology of structure (micellar, lamellar, hexagonal phases). It was observed that the reverse micelles size increases with increasing water concentration and decreases with increasing temperature, without any phase transition. On the contrary the normal micelles become anisometric on temperature, showing a transition to a liquid crystalline phase. The observed mechanical spectra of the liquid crystalline phases are typical of hexagonal and lamellar phases according to the literature [1, 2]. A phase transition with temperature was found for both liquid crystalline phase (lamellar and hexagonal) by rheological tests and was confirmed by ocular inspection.
Influence of the Molar Mass Distribution on the Elongational Behaviour of Polymer Solutions in Capillary Breakup
Authors: Plog J. P. , Kulicke W.-M. , Clasen C. 
Published: May 2019

AbstractCommercially available, blended methylhydroxyethyl celluloses with similar weight-average molar masses but varying molar mass distributions were characterized by different techniques like steady shear flow and uniaxial elongation in capillary breakup experiments. The determined relaxation times t were then correlated with the absolute molar mass distribution acquired via SEC/MALLS/DRI (combined methods of size-exclusion-chromatography, multi angle laser light scattering and differential refractometer). In order to describe the longest relaxation time of the polymers in uniaxial elongation via integral mean values of the molar mass distribution, defined blends of polystyrene standards with varying molar mass distributions were characterized. The obtained data was scaled via different moments of the molecular weight distribution and could be correlated with the results obtained for the methylhydroxyethyl celluloses.
Freezing as a Storage Process for Aqueous Polymer Solutions
Authors: Escudier M. P. , Clement-Evans J. , Poole R. J. 
Published: May 2019

Abstract
There is often a need to perform rheological tests on dilute polymeric liquids at a time long after their initial preparation, for example if a more sensitive or novel method of measuring a material property (such as uniaxial/biaxial extensional viscosity or second normal-stress differences) becomes available. An inexpensive method of storing such fluids which prevents any form of deterioration (e.g. bacteriological) would therefore be of great value. This study explores the potential of freezing as that storage process by investigating whether the freeze-thaw process itself leads to rheological changes. The rheological properties of three polymeric liquids: 0.25 % xanthan gum, 0.125% polyacrylamide and a 0.1 %/0.1 % carboxymethylcellulose / xanthan gum blend commonly used in non-Newtonian fluid flow studies were determined in both shear and oscillation before and after a freeze-thaw process. Within the uncertainty of the rheometer used, the rheological properties of the polymers studied were found to be unaffected by the freeze-thaw process leading to the conclusion that this storage method is indeed a practical possibility.
Rheology Innovation in the Study of Mixing Conditions of Polymer Blends during Chemical Reaction
Authors: Lacoste C. , Choplin L. , Cassagnau P. , Michel A. 
Published: May 2019

Abstract
Polymer melts can be mixed with many monomers, plasticizers, antistatics or foaming additives. Properties of such mixtures can change during blending because of chemical reactions like polymerization or crosslinking. The process may be carried out either in stirred tanks, extruders or in motionless mixers. In this paper we focused on the mixing time and the diffusion time of reagent, plasticizer and polymer thanks to rheological tools, and on the way how rheological properties can be studied during chemical reaction in polymer blending. The concept of rheoreactor and Couette analogy were introduced since we have a reactor on our disposal that can mix solution and measure rheological properties without taking sample. This apparatus appears to be an appreciable tool in complement of internal mixers that are specific to polymer blending. For example, we show the importance of the competition between mixing time and reaction time for reactive systems.
Rheology and stability of self-compacting concrete cement pastes
Authors: Phan T. H. , Chaouche M. 
Published: May 2019

Abstract
The rheological behaviour of a cement paste used in Self-Compacting Concretes (SCC) formulations is compared to that of an “ordinary” cement paste (OC) devoid of organic admixtures. In order to mimic the flow conditions experienced by the cement paste in the inter granular space of concretes, the rheological behaviour is investigated in a squeeze flow geometry. By considering the evolution of the squeeze force for different velocities as a function of the instantaneous distance between the discs, it is found that the behaviors of the two cement pastes are qualitatively different. For the OC pastes, the force decreases with increasing squeeze velocity for any given discs separation, indicating that the material is undergoing fluid-solid separation due to filtration of the fluid phase through the porous media made up by the grains. Such behaviour reflects the very poor flowability of the OC paste. The behaviour of the SCC paste is qualitatively different. Above a certain critical value of the speed Uc, the force is an increasing function of the speed for any given disc separation. Under these flow conditions the rheological behaviour of the material is that of a viscous, although highly non-Newtonian, fluid which corresponds to the flowability conditions of the material. For squeeze speeds smaller than Uc, the rheological behaviour of the SCC paste is similar that of OC, indicating that below this critical velocity the material undergoes solid-fluid separation corresponding then to its non-flowability zone.
The Rheology of Blood Flow in a Branched Arterial System
Authors: Shibeshi Shewaferaw S. , Collins William E. 
Published: May 2019

AbstractBlood flow rheology is a complex phenomenon. Presently there is no universally agreed upon model to represent the viscous property of blood. However, under the general classification of non-Newtonian models that simulate blood behavior to different degrees of accuracy, there are many variants. The power law, Casson and Carreau models are popular non-Newtonian models and affect hemodynamics quantities under many conditions. In this study, the finite volume method is used to investigate hemodynamics predictions of each of the models. To implement the finite volume method, the computational fluid dynamics software Fluent 6.1 is used. In this numerical study the different hemorheological models are found to predict different results of hemodynamics variables which are known to impact the genesis of atherosclerosis and formation of thrombosis. The axial velocity magnitude percentage difference of up to 2 % and radial velocity difference up to 90 % is found at different sections of the T-junction geometry. The size of flow recirculation zones and their associated separation and reattachment point’s locations differ for each model. The wall shear stress also experiences up to 12 % shift in the main tube. A velocity magnitude distribution of the grid cells shows that the Newtonian model is close dynamically to the Casson model while the power law model resembles the Carreau model.
Publication Specific Impact of Articles Published by Rheological Journals
Authors: Kröger Martin 
Published: May 2019

Abstract
The Impact Factor of a journal is a quantitative way of assessing its worth and relevance to the academic community it serves. Many librarians see the ratio between Impact Factor and price as a suitable yardstick by which to measure the value of their collections. In addition, the research assessment exercises which, in many countries, are now being carried out on a more formal basis mean that authors submitting original research must publish it in a journal with the highest perceived worth possible in order to secure future funding, job promotions and peer recognition. It has been suspected [T. Opthof, Cardiovasc. Res. 33 (1997) 1; J. Stegmann, Nature 390 (1990) 550], however, that a particular author’s impact is not much related to the journals in which her/he publishes. As will be demonstrated in this letter, the impact of articles published in rheological journals is largely influenced by criteria such as length of article, number of authors, number of cited references.
Corrosion of copper intrauterine devices: review and recent developments
Authors: Bastidas David M. , Valdez Benjamin , Schorr Michael , Bastidas Jose M. 
Published: May 2019

AbstractA systematic review of the literature about the corrosion of copper in intrauterine devices (IUDs) was conducted, an important topic of copper application that apparently may not be well known to a broad corrosion audience. Copper IUDs (Cu-IUDs) are one of the most widely used contraceptive methods around the world, particularly in China, India, and Latin America. The contraceptive method is based on the release of copper ions from a Cu-IUD. Copper ions enhance the inflammatory response in the uterine cavity and reach concentrations in the luminal fluids of the genital tract, which are toxic for spermatozoa and embryos. A description is made of the different types of Cu-IUD used, the traditional T-shaped device, copper nanoparticles inside a polymeric matrix, and other shapes. This review aims to discuss the main parameters affecting the efficiency of a Cu-IUD, the contraceptive mechanism, and the shape of the device. The high copper corrosion rate immediately after insertion in the uterus (“burst release”) is discussed, which presents values of the order of up to 296 μg/day, causing side effects such as bleeding and pain, with an exponential decay defining a steady-state plateau after 1–2 months of insertion with values of 40 μg/day for a 200 mm2Cu-IUD. This plateau is maintained over the life span of a Cu-IUD, in which the copper dissolution rate is as low as 2 μg/day for a Cu-IUD with indomethacin keeping up the contraceptive action mechanism, the concentration of copper that needs to be higher than 10−6mol/l.
Efficacy of curcuminoids for reducing postoperative pain after laparoscopic gynecologic surgery: A pilot randomized trial
Authors: Phoolcharoen Natacha , Oranratanaphan Shina , Ariyasriwatana Chai , Worasethsin Pongkasem 
Published: May 2019

Abstract

Background
Curcuminoids, which are substances extracted from turmeric, have been proved to have anti-inflammatory and analgesic effects along with a good safety profile. This study aimed to evaluate the clinical efficacy of curcuminoids for reducing postoperative pain in patients who undergo laparoscopic gynecologic surgery.

Methods
From November 2016 to December 2017, participants were randomly assigned, by blocks of four, to the intervention and control arms of the study. Altogether, 60 patients who were to undergo laparoscopic gynecologic surgery at our institution were enrolled. Intraoperative findings were not significantly different between the two groups. One tablet of curcuminoid extract 250 mg was given to patients in the intervention group four times a day on postoperative days 1–3. Pain was evaluated at 24 and 72 h postoperatively using a 10-point visual analog scale (VAS).

Results
The median VAS score 24 h after surgery was 3 (1–6) in the intervention group and 4.5 (3–7) in the control group, with the difference reaching statistical significance (p=0.001). The median VAS at 72 h after surgery was 1 (0–2) in the intervention group and 2 (1–5) in the control group (p<0.001).

Conclusion
Curcuminoids may be an effective supplement to reduce pain severity postoperatively following laparoscopic gynecologic surgery.

Trial Registration
TCTR20180215001 www.clinicaltrials.in.th
Determinants for low bone mineral density in pre-school children: a matched case-control study in Wuhan, China
Authors: Ren Yali , Xi Xiaoyan , Hu Dan , Shang Weifeng , Peng Songxu , Fan Linlin , Tu Si , Zhang Hongping , Shen Min , Du Yukai 
Published: May 2019

Abstract

Introduction
Reduced bone mass will increase bone fragility and risk of fractures. Thus, it is better to note its determinants as early as possible.

Objective
This study aimed to find and determine the determinants for low bone mineral density (BMD) in pre-school children.

Methods
Between November 2014 and April 2015, a matched case-control study was performed to detect information on growth and development condition and consumption frequency of products of cases with low BMD and controls with normal BMD. Anthropometric data measurement and blood tests were conducted. Besides, the questionnaires concerning the mentioned information were completed to get relevant determinants. A paired t-test, the McNemar test and univariate and multiple conditional logistic regression models were used to explore the association between these factors and low BMD.

Results
In total, 88 (28 boys, 60 girls) incident cases (4.15 ± 0.78 years) of low BMD and 88 sex- and age-matched (±2 months) controls (4.16 ± 0.80 years) of normal BMD were enrolled. The results of multiple conditional logistic regression analysis indicated that if children had larger chest circumference (odds ratio [OR] = 0.763), longer duration of breastfeeding (OR = 0.899) and lower frequency of eating snacks (OR = 0.439), the risk of low BMD would decrease.

Conclusions
Our findings suggest that pre-school children with an association of larger chest circumference, longer duration of breastfeeding and lower frequency of eating snacks could have lower risk for low BMD. Intended measures to strengthen those protective factors could be effective in reducing the cases of low BMD.