Melt elasticity and flow properties of polypropylene impact copolymer/polyolefin elastomer blends subjected to varied capillary extrusion conditions

2021 ◽  
pp. 147776062110194
Author(s):  
Vishal Das ◽  
AK Pandey ◽  
DN Tripathi ◽  
NE Prasad
Keyword(s):  
Shear Flow ◽  
Elastic Properties ◽  
Flow Behavior ◽  
Elongational Flow ◽  
Theoretical Models ◽  
Cross Model ◽  
First Normal Stress Difference ◽  
Polyolefin Elastomer ◽  
Elongational Flows ◽  
Capillary Extrusion

In present study, rheological properties of polypropylene impact copolymer (PPcp) and polyolefin elastomer (POE) blend melts were evaluated on a capillary rheometer under shear and elongational flows. The flow and melt elastic properties (die swell and first normal stress difference) studied at varied extrusion conditions were correlated with blend morphology and elastomer content by means of image analysis and theoretical models. Dispersed particle break-up and coalescence were observed to be influenced by POE content and the viscosities of the constituent polymers which were in turn affected by the capillary extrusion conditions (shear rate in particular). The blend melts demonstrated typical pseudoplastic behavior obeying Cross model under shear flow. The elongational flow also corroborated well with the shear flow behavior. All the blends illustrated prominent dependence of melt elastic properties on POE content and the capillary extrusion conditions. The melt elastic properties were also found to critically rely on the inter-particle distance of the POE phase.

scholarly journals Interrelationships of Pressure-Dependent Hole Fraction and Elongational Viscosity in Polymer Melts

2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Fatma Sahin-Dinc ◽  
Ugur Yahsi ◽  
Tomas Sedlacek
Keyword(s):  
High Pressures ◽  
Flow Behavior ◽  
Measurement Data ◽  
Elongational Flow ◽  
Elongational Viscosity ◽  
Viscosity Data ◽  
Cross Model ◽  
Elevated Pressures ◽  
The Cross ◽  
Hole Fraction

The elongational flow behavior of polyethylene, polypropylene, polystyrene, poly(methyl methacrylate), and polycarbonate, temperatures from 70 to 290 °C and pressures up to 70 MPa, is examined with the Yahsi-Dinc-Tav (YDT) model and its particular case known as the Cross model. The viscosity data employed in the range of 3-405 s-1 elongational rates were acquired from the literature at ambient and elevated pressures. The predictions and the fitting results of the proposed YDT model with the same measurement data are compared with the Cross model. The average absolute deviations of the viscosities predicted by the YDT model range from 0.54% to 9.44% at ambient and 1.95% to 6.28% at high pressures. Additionally, the linear formulations derived from the YDT model are employed to relate the viscosity with temperature and hole fraction (“thermooccupancy” function) at zero level of elongational rate and constant elongational rate along with constant elongational stress. The effects of the four viscosity parameters (such as transmission and activation energy coefficients in these equations) on the elongational viscosity are analyzed in detail and some conclusions on the structural differences for the polymers are discussed.

scholarly journals A Study of Viscoelastic Model of Polymers in Shear Flow Based on Molecular Dynamic Simulations

2021 ◽  
Author(s):  
Donglei LIU ◽  
Haizhen ZHOU ◽  
Kun FANG ◽  
Chuanliang CAO
Keyword(s):  
Shear Flow ◽  
Flow Behavior ◽  
Viscoelastic Model ◽  
Rheological Characteristic ◽  
Power Law Model ◽  
Dynamic Simulations ◽  
Cross Model ◽  
Molecular Dynamics Calculations ◽  
Sample Data ◽  
Plastic Fluids

In this study, the rheological properties and physical significations of an incompressible viscoelastic (inCVE) the inCVE model was investigated by employing molecular dynamics calculations. Polypropylene (PP) and polystyrene (PS) polymers were selected as candidate materials, the corresponding cell models consisting of five chains of 80 (PP) and 30 (PS) units were built successively. The energy minimization and anneal treatment were launched to optimize the unfavorable structures. The periodic boundary condition, COMPASS force field and the Velocity-Verlet algorithm were employed to calculate the shear flow behavior of chains. The sample data were collected and fitted based on the Matlab platform, and the analysis of the variance (ANOVA) method was performed to determine the validity of the model. Experimental results reveal that the inCVE model matches well with the pseudo-plastic fluids. Compared with the Ostwald-de Waele power law model and Cross model, it is effective and robust, and exhibits a three-stage rheological characteristic. Moreover, it characterizes the stress yield, activation energy, temperature dependence and viscoelastic response of polymers.

scholarly journals Shear flow behavior and dynamic viscosity of few-layer graphene nanofluids based on propylene glycol-water mixture

2020 ◽  
Vol 316 ◽  
pp. 113875 ◽  
Author(s):  
Samah Hamze ◽  
David Cabaleiro ◽  
Thierry Maré ◽  
Brigitte Vigolo ◽  
Patrice Estellé
Keyword(s):  
Shear Flow ◽  
Propylene Glycol ◽  
Dynamic Viscosity ◽  
Flow Behavior ◽  
Water Mixture ◽  
Layer Graphene ◽  
Few Layer Graphene

Comparison of three rheological models of shear flow behavior studied on blood samples from post-infarction patients

2007 ◽  
Vol 45 (9) ◽  
pp. 837-844 ◽  
Author(s):  
Anna Marcinkowska-Gapińska ◽  
Jacek Gapinski ◽  
Waldemar Elikowski ◽  
Feliks Jaroszyk ◽  
Leszek Kubisz
Keyword(s):  
Shear Flow ◽  
Flow Behavior ◽  
Rheological Models ◽  
Blood Samples

Shear flow behavior of a dynamically symmetric polymeric bicontinuous microemulsion

2007 ◽  
Vol 51 (5) ◽  
pp. 1027-1046 ◽  
Author(s):  
Ning Zhou ◽  
Frank S. Bates ◽  
Timothy P. Lodge ◽  
Wesley R. Burghardt
Keyword(s):  
Shear Flow ◽  
Flow Behavior ◽  
Bicontinuous Microemulsion

Shear Flow Analysis of Nanosize Particle Flow Behavior Using Kinetic Theory

2005 ◽  
Vol 277-279 ◽  
pp. 939-944
Author(s):  
Hae Ryung Kim ◽  
Jaihyun Seu ◽  
Hamid Arastoopour
Keyword(s):  
Shear Flow ◽  
Kinetic Theory ◽  
Flow Behavior ◽  
Flow Analysis ◽  
Particle Diameter ◽  
Particle Flow ◽  
Particle Collision ◽  
Simple Shear Flow ◽  
Particle Force ◽  
Nanosize Particle

Nanosize particle flow is significantly affected by inter-particle force. Due to the inter-particle force, the most significant characteristic of nanosize particle flow may become the formation of agglomerates or clusters which considerably affects the flow patterns. The formation of agglomerates or clusters results in a reduction in the number and an increase in the size of particles, both of which directly affect the frequency of inter-particle collisions and, in turn, the particle phase properties such as viscosity and pressure, as well as gas/particle drag force in gas/particle flow systems. In this present work, we focus our attention on the verification of nanosize particle flow behavior due to the formation of agglomerates or clusters under different fluctuation of flow and inelasticity of particle collision. By extending the application of the cohesive model using kinetic theory to nanosize particle flow system, we performed the homogeneous simple shear flow analysis using various fluctuation energy and restitution coefficient. The predicted flow properties, such as particle diameter growth, agreed well with the expected trends.

Generation of Short-scale Electrostatic Fields in the Solar Atmosphere and the Role of Helium Ions

2021 ◽  
Vol 922 (1) ◽  
pp. 48
Author(s):  
H. Saleem ◽  
Shaukat Ali Shan ◽  
A. Rehman
Keyword(s):  
Shear Flow ◽  
Transition Region ◽  
Electric Fields ◽  
Hydrogen Plasma ◽  
Theoretical Models ◽  
Inhomogeneous Field ◽  
Helium Ions ◽  
Low Frequencies ◽  
Short Scale

Abstract Theoretical models are presented to show that expansion of plasma in the radial direction from a denser solar surface to a rarefied upper atmosphere with short-scale inhomogeneous field-aligned flows and currents in the form of thin threads itself is an important source of electrostatic instabilities. Multifluid theory shows that the shear flow–driven purely growing electric fields appear in the transition region. On the other hand, plasma kinetic theory predicts that the short-scale current sheets (or filaments) produce current-driven electrostatic ion acoustic (CDEIA) waves in the hydrogen plasma of the transition region that damp out in the system through wave–particle interactions and increase the temperature. Similar processes take place in the solar corona and act positively for increasing the temperature further and maintaining it. The shear flow–driven instabilities and CDEIA waves have short perpendicular wavelengths of the order of 1 m and low frequencies of the order of 1 or several Hz when the ions’ shear flow scale length is considered to be of the order of 1 km. It is pointed out that the purely growing fluid instabilities turn into oscillatory instabilities and the growth rates of kinetic CDEIA wave instabilities are reduced when the dynamics of 10% helium ions is taken into account along with 90% hydrogen ions. Therefore, the role of helium ions should not be ignored in the study of wave dynamics in solar plasma.

The first normal stress difference of non-Brownian hard-sphere suspensions in the oscillatory shear flow near the liquid and crystal coexistence region

Soft Matter ◽  
2020 ◽  
Vol 16 (43) ◽  
pp. 9864-9875
Author(s):  
Young Ki Lee ◽  
Kyu Hyun ◽  
Kyung Hyun Ahn
Keyword(s):  
Shear Flow ◽  
Normal Stress ◽  
Hard Sphere ◽  
Normal Stress Difference ◽  
Oscillatory Shear ◽  
Stress Difference ◽  
Large Amplitude Oscillatory Shear ◽  
First Normal Stress Difference ◽  
Oscillatory Shear Flow ◽  
Sphere Suspensions

The first normal stress difference (N1) as well as shear stress of non-Brownian hard-sphere suspensions in small to large amplitude oscillatory shear flow is investigated.

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