scholarly journals Effect of D-Mannitol on the Microstructure and Rheology of Non-Aqueous Carbopol Microgels

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1782
Author(s):  
Simona Migliozzi ◽  
Panagiota Angeli ◽  
Luca Mazzei
Keyword(s):  
Rheological Behaviour ◽  
Crystalline Form ◽  
Dispersed Phase ◽  
Chemical Similarity ◽  
Interparticle Interactions ◽  
Time Resolved ◽  
Rheological Analysis ◽  
Personal Care Product ◽  
Infinitesimal Deformations ◽  
Yielding Process

D-mannitol is a common polyol that is used as additive in pharmaceutical and personal care product formulations. We investigated its effect on the microstructure and rheology of novel non-aqueous Carbopol dispersions employing traditional and time-resolved rheological analysis. We considered two types of sample, (i) fresh (i.e., mannitol completely dissolved in solution) and aged (i.e., visible in crystalline form). The analysis of the intracycle rheological transitions that were observed for different samples revealed that, when completely dissolved in solution, mannitol does not alter the rheological behaviour of the Carbopol dispersions. This highlights that the chemical similarity of the additive with the molecules of the surrounding solvent allows preserving the swollen dimension and interparticle interactions of the Carbopol molecules. Conversely, when crystals are present, a hierarchical structure forms, consisting of a small dispersed phase (Carbopol) agglomerated around a big dispersed phase (crystals). In keeping with this microstructural picture, as the concentration of Carbopol reduces, the local dynamics of the crystals gradually start to control the integrity of the microstructure. Rheologically, this results in a higher elasticity of the suspensions at infinitesimal deformations, but a fragile yielding process at intermediate strains.

Morphology and Rheological Analysis of Nanoclay in Polymer Modified Bitumen

2012 ◽  
Vol 509 ◽  
pp. 155-161 ◽  
Author(s):  
Ji Zhe Zhang ◽  
Martin Van de Ven ◽  
Shao Peng Wu
Keyword(s):  
Particle Size ◽  
Fluorescence Microscopy ◽  
Rheological Properties ◽  
Rheological Behaviour ◽  
Dynamic Shear ◽  
Polymer Particles ◽  
Modified Bitumen ◽  
Rheological Analysis ◽  
Fixed Proportion ◽  
Polymer Modified Bitumen

This paper investigated the influence of nanoclay on the properties of polymer modified bitumen(PMB). The nanoclay-polymer modified bitumen has been produced by mixing a standard 70/100 pen bitumen with polymer at a fixed proportion and then mixed with different amount of nanoclay. The rheological behaviour of the samples have been determined using dynamic shear rheometer. The morphology of the samples as well as the distribution of polymer and nanoclay throughout the bitumen have been characterized with a fluorescence microscopy. The result indicate that the rheological properties of nanoclay-polymer modified bitumens dependent on the percentage nanoclay. The morphology result shows that dispersed polymer particles existed in continuous bitumen phase and the addition of nanoclay does not seem to change the particle size of the polymer.

Processing/Structure/Properties Relationships in Polymer Blends for the Development of Functional Polymer Foams

2015 ◽  
Author(s):  
Ali Rizvi ◽  
Chul B. Park
Keyword(s):  
Strain Hardening ◽  
Elastic Properties ◽  
Crystallization Kinetics ◽  
Extensional Flow ◽  
Relaxation Times ◽  
Rheological Behaviour ◽  
Polymer Processing ◽  
Phase Morphology ◽  
Dispersed Phase ◽  
Carbon Dioxide Co2

In this study we present a comprehensive experimental investigation of the effect of polymer blending on the dispersed phase morphology and how the dispersed phase morphology influences the foaming behavior of the semicrystalline polymer matrix using three different material combinations: polyethylene (PE)/polypropylene (PP), PP/polyethylene terephthalate (PET) and PP/polytetrafluoroethylene (PTFE). Samples are prepared such that the dispersed phase domains exhibit either spherical or fibrillated morphologies. Measurements of the uniaxial extensional viscosity, linear viscoelastic properties and crystallization kinetics under ambient pressures and elevated pressures of carbon dioxide (CO2) are performed and the morphological features are identified with the aid of SEM. Batch foaming and lab-scale extrusion foaming experiments are performed, as a screening model for polymer processing, to show the enhancement of the foaming ability as a result of the blend morphology, taking into account the rheological behaviour and the effects of crystallization kinetics. The formation of high aspect ratio fibrils imparts unique characteristics to the semicrystalline matrix such as strain-hardening in uniaxial extensional flow, prolonged relaxation times, pronounced elastic properties and enhanced kinetics of crystallization. In contrast, the regular blends containing spherical dispersed phase domains do not exhibit such properties. Foam processing of the three blends reveals a marked broadening of the foaming window when the dispersed phase domains are fibrillated due to the concurrent increase in crystallization kinetics, improved elastic properties and strain hardening in extensional flow.

Mathematical Description of Semi-Solid Magnesium Alloys Behaviour by Using Rheological Models

2019 ◽  
Vol 952 ◽  
pp. 37-44
Author(s):  
Marta Ślęzak
Keyword(s):  
Magnesium Alloys ◽  
Solid Phase ◽  
Rheological Behaviour ◽  
The Other ◽  
Light Weight ◽  
Rheological Characteristics ◽  
Rheological Models ◽  
Plastic Properties ◽  
Rheological Analysis ◽  
Semi Solid

This paper is a study of rheological analysis of magnesium alloys of groups Mg-Zn-Al and Mg-Zn-RE. It presents the results of high-temperature measurements of magnesium alloys, along with rheological analysis of their behaviour. Magnesium alloys are a very attractive material, due to their light weight and good plastic properties; on the other hand this material is very reactive in a liquid (semi-solid) state, which is challenging from a testing and forming perspective. The findings obtained were compared with five types of rheological models describing rheological characteristics of viscous systems. The analysis was carried out using Rheoplus software. As a result of the conducted work, the mathematical descriptions which are best for characterising rheological behaviour of semi-solid magnesium alloys containing 20% of the solid phase have been proposed.

Novel Particle Shift Filtering Method for Simultaneous Two Phase Separation in Time Resolved Stereo PIV Measurements

2007 ◽  
Author(s):  
Y. Cheng ◽  
M. M. Torregrosa ◽  
F. J. Diez
Keyword(s):  
Turbulent Flows ◽  
Particle Dispersion ◽  
Dispersed Phase ◽  
Two Phase ◽  
Time Resolved ◽  
Ambient Flow ◽  
Filtering Method ◽  
Tracer Particles ◽  
Coal Particles ◽  
A New Technique

This paper describes a novel particle shift filtering method to study jets laden with particles by separating the 3D velocity field of the two phases. Multiphase jets laden with particles appear in many engineering and environmental processes. Typical examples are sprays containing liquid fuel drops in combustion processes, air jets laden with coal particles in a power plant, and the dispersion of harmful substances like soot and pollutants from steady exhaust flows or waste waters, among others. Distribution and mixing of particles/drops in these processes determine the efficiency of the engineering systems concerned but studies of particle-laden turbulent flows suggest that particle distribution is not uniform but preferential. In order to understand the mechanism of particle dispersion, the dispersed phase (particles/drops) needs to be separated from the ambient flow (tracer particles). A new technique is proposed that builds on previous work done by Kiger & Pan (2000) and Khalitov & Longmire (2002). The later work used a discrimination algorithm for two-phase 2D PIV where the tracer particles are differentiated from the dispersed phase based on size and brightness intensity. The present work expands on that technique and introduces a 3D velocity discrimination algorithm of two-phase flows for time resolved stereo PIV.

Rheological Analysis of Ceramics Suspensions with High Solids Loading

2012 ◽  
Vol 727-728 ◽  
pp. 646-651 ◽  
Author(s):  
Luiz Fernando Grespan Setz ◽  
Laís Koshimizu ◽  
Sonia Regina Homem de Mello-Castanho ◽  
Márcio Raymundo Morelli
Keyword(s):  
Rheological Behaviour ◽  
Rheological Parameters ◽  
High Solids ◽  
Rheological Analysis ◽  
Solids Loading ◽  
High Solids Loading ◽  
Shaping Process ◽  
Slip Cast ◽  
And Control ◽  
Alumina Suspensions

The pure oxides (yttria, zirconia, titania, alumina, etc.) pastes ceramics production by concentrate suspensions is interesting because differently than plastic ceramics (clays), where these behaviours are often empirical available, the rheological suspensions behaviour are extensively studied. Thus, controlling the concentrate slips rheological parameters, is possible extend these analysis for better understand and control the plastic pastes production, providing subsidies to obtain after shaping process, such as extrusion and calendering, suitable products for the desired application. Thus, alumina suspensions rheological behaviour, with high solids loading (> 50 vol.%) adequately stabilized, slip cast shaped are available in this work. High solids loading suspensions, up to 60 vol.%, presents adequate flow for thickeners/plasticizers elements adds to produce ceramic plastic pastes.

The role of the dispersed-phase remnant magnetization on the redispersibility of magnetorheological fluids

1999 ◽  
Vol 14 (7) ◽  
pp. 3037-3041 ◽  
Author(s):  
Pradeep P. Phulé ◽  
Matthew P. Mihalcin ◽  
Seval Genc
Keyword(s):  
Interaction Energy ◽  
Zinc Ferrite ◽  
Magnetic Interaction ◽  
Dispersed Phase ◽  
Remnant Magnetization ◽  
Interparticle Interactions ◽  
Manganese Zinc ◽  
Mr Fluids ◽  
Manganese Zinc Ferrite ◽  
Cake Formation

The influence of the remnant magnetization of the soft magnetic particulates, used as a dispersed phase, on the redispersibility of magnetorheological (MR) fluids is discussed. Calculations of the magnetic interaction energy showed that for 33-vol% MR fluids based on particles of iron (∼6 μm), manganese zinc ferrite (∼2.3 μm), and nickel zinc ferrite (∼2.1 μm), the ratios of the magnetic interaction energy to the thermal energy were 161,000, 6400, and 3900, respectively. These calculations showed that even the seemingly small levels of remnant magnetization, associated with particulates employed in MR fluids, introduced significant dipole–dipole interparticle interactions. It is proposed that this interaction causes most MR fluids to show a tendency for “cake formation,” which makes it difficult to redisperse these fluids. Our modeling presented here also suggests practical strategies to enhance the redispersibility of MR fluids.

A Comparison Between Round Turbulent Jets and Particle-Laden Jets in Crossflow by Using Time-Resolved Stereoscopic Particle Image Velocimetry

2011 ◽  
Vol 133 (9) ◽  
Author(s):  
F. J. Diez ◽  
M. M. Torregrosa ◽  
S. Pothos
Keyword(s):  
Particle Image Velocimetry ◽  
High Intensity ◽  
Particle Image ◽  
Three Dimensional ◽  
Continuous Phase ◽  
Stereoscopic Particle Image Velocimetry ◽  
Dispersed Phase ◽  
Time Resolved ◽  
Image Velocimetry ◽  
Phase Images

Time-resolved stereoscopic particle image velocimetry (TR-ST-PIV) measurements were performed to compare the velocity and vorticity field, and the three-dimensional high intensity vorticity structures between a round turbulent single-phase jet and a particle-laden jet in crossflow. The experiments involved steady fresh water jet sources with a particle mass loading of ∼2.0% injected into steady fresh water crossflows. The TR-ST-PIV system was combined with a phase discrimination method that separates two-phase stereo PIV images into dispersed phase images and continuous phase images that are analyzed by using particle tracking velocimetry and stereo-PIV algorithms, respectively. The analysis shows the importance of phase separation for accurate velocity results. It provides instantaneous velocity fields where the dispersed phase preferentially concentrated in regions of low vorticity with the velocity not matching the continuous phase. The jet and the particle-laden jets trajectories are compared to each other and with results in the literature. Similarly, a comparison of mean velocity and vorticity fields between both flows suggest enhanced mixing in the particle-laden jet due to the effects of the dispersed phased which lowered the centerline velocities and enhanced the penetration in the cross-stream direction of the continuous phase. The Taylor’s frozen flow hypothesis is applied to reconstruct the 3D high intensity vorticity structures in a volume. The visualization of the three-dimensional structures corresponding to the intermediate scales of the flow shows slightly elongated structures preferentially aligned with the jet centerline axis.

Stochasting modeling of planetary ring systems

1984 ◽  
Vol 75 ◽  
pp. 461-469 ◽  
Author(s):  
Robert W. Hart
Keyword(s):  
Maximum Entropy ◽  
Ring System ◽  
The Sun ◽  
Ultimate State ◽  
Interparticle Interactions ◽  
Ring Systems ◽  
First Order ◽  
Planetary Ring ◽  
Insight Into

ABSTRACTThis paper models maximum entropy configurations of idealized gravitational ring systems. Such configurations are of interest because systems generally evolve toward an ultimate state of maximum randomness. For simplicity, attention is confined to ultimate states for which interparticle interactions are no longer of first order importance. The planets, in their orbits about the sun, are one example of such a ring system. The extent to which the present approximation yields insight into ring systems such as Saturn's is explored briefly.

Microtubule nucleation sequence studied by time-resolved x-ray scattering and electron microscopy

1983 ◽  
Vol 41 ◽  
pp. 766-767
Author(s):  
Eva-Maria Mandelkow ◽  
Eckhard Mandelkow ◽  
Joan Bordas
Keyword(s):  
Electron Microscopy ◽  
Dynamic Equilibrium ◽  
Time Resolved ◽  
X Ray ◽  
Additional Information ◽  
X Ray Scattering ◽  
Low Concentrations ◽  
Microtubule Growth ◽  
Ray Patterns ◽  
Ray Scattering

When a solution of microtubule protein is changed from non-polymerising to polymerising conditions (e.g. by temperature jump or mixing with GTP) there is a series of structural transitions preceding microtubule growth. These have been detected by time-resolved X-ray scattering using synchrotron radiation, and they may be classified into pre-nucleation and nucleation events. X-ray patterns are good indicators for the average behavior of the particles in solution, but they are difficult to interpret unless additional information on their structure is available. We therefore studied the assembly process by electron microscopy under conditions approaching those of the X-ray experiment. There are two difficulties in the EM approach: One is that the particles important for assembly are usually small and not very regular and therefore tend to be overlooked. Secondly EM specimens require low concentrations which favor disassembly of the particles one wants to observe since there is a dynamic equilibrium between polymers and subunits.

Electron Channeling Patterns

1977 ◽  
Vol 35 ◽  
pp. 12-13
Author(s):  
David C. Joy
Keyword(s):  
Electron Diffraction ◽  
Incidence Angle ◽  
Photographic Plate ◽  
Diffraction Effect ◽  
Angle Of Incidence ◽  
Bulk Single Crystal ◽  
Time Resolved ◽  
Electron Channeling ◽  
Spatially Resolved ◽  
Large Bulk

Electron channeling patterns (ECP) were first found by Coates (1967) while observing a large bulk, single crystal of silicon in a scanning electron microscope. The geometric pattern visible was shown to be produced as a result of the changes in the angle of incidence, between the beam and the specimen surface normal, which occur when the sample is examined at low magnification (Booker, Shaw, Whelan and Hirsch 1967).A conventional electron diffraction pattern consists of an angularly resolved intensity distribution in space which may be directly viewed on a fluorescent screen or recorded on a photographic plate. An ECP, on the other hand, is produced as the result of changes in the signal collected by a suitable electron detector as the incidence angle is varied. If an integrating detector is used, or if the beam traverses the surface at a fixed angle, then no channeling contrast will be observed. The ECP is thus a time resolved electron diffraction effect. It can therefore be related to spatially resolved diffraction phenomena by an application of the concepts of reciprocity (Cowley 1969).

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