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Panagiota Angeli - One of the best experts on this subject based on the ideXlab platform.

  • Phase Inversion in liquid-liquid pipe flows
    2010
    Co-Authors: Panagiota Angeli
    Abstract:

    Phase Inversion is the phenomenon where the continuous Phase of a liquid-liquid dispersion changes to become dispersed and the dispersed becomes continuous. Phase Inversion has important implications for a number of industrial applications where liquid-liquid dispersions are used, since the change in the mixture continuity affects drop size, settling characteristics, heat transfer and even the corrosion behaviour of the mixture. In pipeline flows, Phase Inversion is usually accompanied by a step change or a peak in pressure drop. The chapter reviews the work on Phase Inversion during the pipeline flow of liquid-liquid mixtures when no surfactants are present. Investigations have revealed that in pipes a transitional region occurs during Inversion from one Phase continuous to the other, characterized by complex flow morphologies (multiple drops, regions in the flow with different continuity) and even stratification of the two Phases over a range of dispersed Phase volume fractions. The observations on the Phase Inversion process in pipelines are discussed and the parameters which affect the phenomenon are summarized. In addition, the various models available for predicting Phase Inversion are analyzed, as well as the methodologies developed to account for the transitional region with the complex morphologies and the flow stratification and to predict pressure drop during Inversion. © Bentham Science Publishers Ltd.

  • Phase Inversion in dispersed liquid liquid flows
    Experimental Thermal and Fluid Science, 2005
    Co-Authors: Karolina Ioannou, O J Nydal, Panagiota Angeli
    Abstract:

    Abstract Phase Inversion and its effect on pressure gradient during the dispersed flow of two immiscible liquids have been studied for two pipe materials (steel and acrylic) and two pipe sizes (60 and 32 mm ID). Water and oil (796 kg m−3 density and 2.19 mm2 s−1 viscosity) were used as test fluids while the appearance of Phase Inversion in the acrylic pipes was confirmed with the use of impedance ring probes. In the large pipes (steel and acrylic with 60 mm ID) it was found that the Phase Inversion point (oil volume fraction where Inversion appears) depended on whether the Inversion was from oil to water continuous mixture or from water to oil. The difference in the Phase Inversion points between the two dispersion initialisation conditions increased with increasing mixture velocity. No effect of initial conditions on the Inversion point was found for the small acrylic pipe. Phase Inversion was in all cases preceded by a large increase in pressure gradient, which was sharply reduced immediately after the new continuous Phase was established. The pressure gradient peak was sharper and larger at high mixture velocities than at low ones and in the acrylic pipe compared to the steel one. The change in Phase continuity lasted a few minutes and was accompanied by large fluctuations in pressure gradient and mixture impedance.

M. Van Duin - One of the best experts on this subject based on the ideXlab platform.

  • Effect of crosslinking on morphology and Phase Inversion of EPDM/PP blends
    Materials Chemistry and Physics, 2012
    Co-Authors: Carla Filipa Antunes, M. Van Duin, Ana Vera Machado
    Abstract:

    Abstract This study investigates the effect of cross-linking on morphology and Phase Inversion of EPDM/PP blends. Several EPDM/PP blends without and with cross-linking agent were prepared in a Haake batch mixer under constant conditions. The morphology was studied by electronic microscopy (SEM and TEM), and cross-linking was followed by EPDM gel content and swelling. The results showed that the position of the Phase Inversion region is essentially governed by composition, being independent of the viscosity ratio of the EPDM/PP blend. The TPVs’ morphology of the EPDM/PP blend, with 70 and 50 wt% of PP, consists of EPDM cross-linked particles dispersed in the PP matrix. For EPDM-rich composition (30 wt% of PP), the TPVs’ morphology appears to be co-continuous. Even though dynamic vulcanisation of the rubber Phase always improves the dispersion of the EPDM Phase, complete Phase Inversion (from fully dispersed PP in the EPDM matrix to EPDM fully dispersed in the PP matrix) was achieved only with low viscosity EPDM. The results suggest that Phase Inversion driven by cross-linking can occur at viscosity ratios lower than those estimated for the respective EPDM/PP blends at Phase Inversion.

  • Morphology and Phase Inversion of EPDM/PP blends – effect of viscosity and elasticity
    Polymer Testing, 2011
    Co-Authors: Carla Filipa Antunes, M. Van Duin, Ana Vera Machado
    Abstract:

    Abstract This work aims to study the effect of viscosity and elasticity ratios on the morphology and Phase Inversion of ethylene propylene diene monomer (EPDM)/polypropylene (PP) blends. EPDM/PP blends with a wide range of viscosity ratios and compositions were prepared in a Haake batch mixer under constant processing conditions. The composition range of EPDM/PP co-continuous morphology was investigated by selective solvent extraction and scanning electron microscopy (SEM). For the viscosity ratios used (10 −3 to 10 2 ), a substantial composition range of co-continuity morphology was found. Our results suggest that the melt viscosity and elasticity of the major Phase are the main parameters that govern the co-continuity region and Phase Inversion. Results obtained for Phase Inversion compositions were also compared with those predicted by several empirical models developed to predict the Phase Inversion point using dynamic viscoelastic properties of blend components. A good fit of our experimental results was obtained by adjusting the general relationship of the composition as a function of the viscosity ratio and by introducing an exponent and prefactor.

  • morphology development and Phase Inversion during dynamic vulcanisation of epdm pp blends
    European Polymer Journal, 2011
    Co-Authors: Carla Filipa Antunes, Ana Vera Machado, M. Van Duin
    Abstract:

    Abstract Morphology development and Phase Inversion were investigated during dynamic vulcanisation of ethylene–propylene–diene terpolymer (EPDM)/polypropylene (PP) blends. The effects of viscosity ratio and cross-linking reactions were also addressed. EPDM/PP blends were dynamically vulcanised in a Haake batch mixer using resole and SnCl2 as cross-linking agents. The morphology development and cross-linking degree with reaction time were followed by morphology analysis (SEM and TEM) and measurement of EPDM gel content, respectively. For the same reaction time, it was found that the EPDM gel content decreased when the low-molecular-weight EPDM was used. As a result, the morphological development was delayed and the Phase-Inversion point was shifted to higher reaction times, allowing us to monitor morphological development during a thermoplastic vulcanisate (TPV) preparation. Using the low-molecular-weight EPDM and increasing the PP viscosity accelerated the morphological development, shifting Phase-Inversion to lower reaction times. While blend composition influenced final TPV morphology, it had a minor effect on the mechanism of morphological development. A correlation between cross-linking degree and morphology development was established. The results obtained allowed to propose a mechanism of morphology development during dynamic vulcanisation of the EPDM/PP blends, including Phase Inversion.

Amos Ullmann - One of the best experts on this subject based on the ideXlab platform.

  • modeling of Phase Inversion phenomenon in two Phase pipe flows
    International Journal of Multiphase Flow, 2002
    Co-Authors: Neima Brauner, Amos Ullmann
    Abstract:

    Abstract Phase Inversion in oil–water flow systems corresponds to the transitional boundary between oil-in-water dispersion and water-in-oil dispersion. In this study, the criterion of minimum of the system free energy is combined with a model for drop size in dense dispersions to predict the critical conditions for Phase Inversion. The model has been favorably compared with available data on the critical holdup for Phase Inversion. It also provides explanations of features of Phase Inversion phenomena in liquid–liquid pipe flows and in static mixers.

Carla Filipa Antunes - One of the best experts on this subject based on the ideXlab platform.

  • Effect of crosslinking on morphology and Phase Inversion of EPDM/PP blends
    Materials Chemistry and Physics, 2012
    Co-Authors: Carla Filipa Antunes, M. Van Duin, Ana Vera Machado
    Abstract:

    Abstract This study investigates the effect of cross-linking on morphology and Phase Inversion of EPDM/PP blends. Several EPDM/PP blends without and with cross-linking agent were prepared in a Haake batch mixer under constant conditions. The morphology was studied by electronic microscopy (SEM and TEM), and cross-linking was followed by EPDM gel content and swelling. The results showed that the position of the Phase Inversion region is essentially governed by composition, being independent of the viscosity ratio of the EPDM/PP blend. The TPVs’ morphology of the EPDM/PP blend, with 70 and 50 wt% of PP, consists of EPDM cross-linked particles dispersed in the PP matrix. For EPDM-rich composition (30 wt% of PP), the TPVs’ morphology appears to be co-continuous. Even though dynamic vulcanisation of the rubber Phase always improves the dispersion of the EPDM Phase, complete Phase Inversion (from fully dispersed PP in the EPDM matrix to EPDM fully dispersed in the PP matrix) was achieved only with low viscosity EPDM. The results suggest that Phase Inversion driven by cross-linking can occur at viscosity ratios lower than those estimated for the respective EPDM/PP blends at Phase Inversion.

  • Morphology and Phase Inversion of EPDM/PP blends – effect of viscosity and elasticity
    Polymer Testing, 2011
    Co-Authors: Carla Filipa Antunes, M. Van Duin, Ana Vera Machado
    Abstract:

    Abstract This work aims to study the effect of viscosity and elasticity ratios on the morphology and Phase Inversion of ethylene propylene diene monomer (EPDM)/polypropylene (PP) blends. EPDM/PP blends with a wide range of viscosity ratios and compositions were prepared in a Haake batch mixer under constant processing conditions. The composition range of EPDM/PP co-continuous morphology was investigated by selective solvent extraction and scanning electron microscopy (SEM). For the viscosity ratios used (10 −3 to 10 2 ), a substantial composition range of co-continuity morphology was found. Our results suggest that the melt viscosity and elasticity of the major Phase are the main parameters that govern the co-continuity region and Phase Inversion. Results obtained for Phase Inversion compositions were also compared with those predicted by several empirical models developed to predict the Phase Inversion point using dynamic viscoelastic properties of blend components. A good fit of our experimental results was obtained by adjusting the general relationship of the composition as a function of the viscosity ratio and by introducing an exponent and prefactor.

  • morphology development and Phase Inversion during dynamic vulcanisation of epdm pp blends
    European Polymer Journal, 2011
    Co-Authors: Carla Filipa Antunes, Ana Vera Machado, M. Van Duin
    Abstract:

    Abstract Morphology development and Phase Inversion were investigated during dynamic vulcanisation of ethylene–propylene–diene terpolymer (EPDM)/polypropylene (PP) blends. The effects of viscosity ratio and cross-linking reactions were also addressed. EPDM/PP blends were dynamically vulcanised in a Haake batch mixer using resole and SnCl2 as cross-linking agents. The morphology development and cross-linking degree with reaction time were followed by morphology analysis (SEM and TEM) and measurement of EPDM gel content, respectively. For the same reaction time, it was found that the EPDM gel content decreased when the low-molecular-weight EPDM was used. As a result, the morphological development was delayed and the Phase-Inversion point was shifted to higher reaction times, allowing us to monitor morphological development during a thermoplastic vulcanisate (TPV) preparation. Using the low-molecular-weight EPDM and increasing the PP viscosity accelerated the morphological development, shifting Phase-Inversion to lower reaction times. While blend composition influenced final TPV morphology, it had a minor effect on the mechanism of morphological development. A correlation between cross-linking degree and morphology development was established. The results obtained allowed to propose a mechanism of morphology development during dynamic vulcanisation of the EPDM/PP blends, including Phase Inversion.

Ana Vera Machado - One of the best experts on this subject based on the ideXlab platform.

  • Effect of crosslinking on morphology and Phase Inversion of EPDM/PP blends
    Materials Chemistry and Physics, 2012
    Co-Authors: Carla Filipa Antunes, M. Van Duin, Ana Vera Machado
    Abstract:

    Abstract This study investigates the effect of cross-linking on morphology and Phase Inversion of EPDM/PP blends. Several EPDM/PP blends without and with cross-linking agent were prepared in a Haake batch mixer under constant conditions. The morphology was studied by electronic microscopy (SEM and TEM), and cross-linking was followed by EPDM gel content and swelling. The results showed that the position of the Phase Inversion region is essentially governed by composition, being independent of the viscosity ratio of the EPDM/PP blend. The TPVs’ morphology of the EPDM/PP blend, with 70 and 50 wt% of PP, consists of EPDM cross-linked particles dispersed in the PP matrix. For EPDM-rich composition (30 wt% of PP), the TPVs’ morphology appears to be co-continuous. Even though dynamic vulcanisation of the rubber Phase always improves the dispersion of the EPDM Phase, complete Phase Inversion (from fully dispersed PP in the EPDM matrix to EPDM fully dispersed in the PP matrix) was achieved only with low viscosity EPDM. The results suggest that Phase Inversion driven by cross-linking can occur at viscosity ratios lower than those estimated for the respective EPDM/PP blends at Phase Inversion.

  • Morphology and Phase Inversion of EPDM/PP blends – effect of viscosity and elasticity
    Polymer Testing, 2011
    Co-Authors: Carla Filipa Antunes, M. Van Duin, Ana Vera Machado
    Abstract:

    Abstract This work aims to study the effect of viscosity and elasticity ratios on the morphology and Phase Inversion of ethylene propylene diene monomer (EPDM)/polypropylene (PP) blends. EPDM/PP blends with a wide range of viscosity ratios and compositions were prepared in a Haake batch mixer under constant processing conditions. The composition range of EPDM/PP co-continuous morphology was investigated by selective solvent extraction and scanning electron microscopy (SEM). For the viscosity ratios used (10 −3 to 10 2 ), a substantial composition range of co-continuity morphology was found. Our results suggest that the melt viscosity and elasticity of the major Phase are the main parameters that govern the co-continuity region and Phase Inversion. Results obtained for Phase Inversion compositions were also compared with those predicted by several empirical models developed to predict the Phase Inversion point using dynamic viscoelastic properties of blend components. A good fit of our experimental results was obtained by adjusting the general relationship of the composition as a function of the viscosity ratio and by introducing an exponent and prefactor.

  • morphology development and Phase Inversion during dynamic vulcanisation of epdm pp blends
    European Polymer Journal, 2011
    Co-Authors: Carla Filipa Antunes, Ana Vera Machado, M. Van Duin
    Abstract:

    Abstract Morphology development and Phase Inversion were investigated during dynamic vulcanisation of ethylene–propylene–diene terpolymer (EPDM)/polypropylene (PP) blends. The effects of viscosity ratio and cross-linking reactions were also addressed. EPDM/PP blends were dynamically vulcanised in a Haake batch mixer using resole and SnCl2 as cross-linking agents. The morphology development and cross-linking degree with reaction time were followed by morphology analysis (SEM and TEM) and measurement of EPDM gel content, respectively. For the same reaction time, it was found that the EPDM gel content decreased when the low-molecular-weight EPDM was used. As a result, the morphological development was delayed and the Phase-Inversion point was shifted to higher reaction times, allowing us to monitor morphological development during a thermoplastic vulcanisate (TPV) preparation. Using the low-molecular-weight EPDM and increasing the PP viscosity accelerated the morphological development, shifting Phase-Inversion to lower reaction times. While blend composition influenced final TPV morphology, it had a minor effect on the mechanism of morphological development. A correlation between cross-linking degree and morphology development was established. The results obtained allowed to propose a mechanism of morphology development during dynamic vulcanisation of the EPDM/PP blends, including Phase Inversion.