The Experts below are selected from a list of 141 Experts worldwide ranked by ideXlab platform

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

  • modelling the zero shear viscosity of bimodal high solid content latex calculation of the Maximum Packing Fraction
    Chemical Engineering Science, 2006
    Co-Authors: M Pishvaei, C Graillat, Philippe Cassagnau, Timothy F L Mckenna
    Abstract:

    Abstract Different rheological tests were performed on monodisperse polystyrene latices and mixtures of two different latices with different particle sizes. A critical volume Fraction φ c was defined for each of the latices. Subsequently, a method based on the estimation of the porosity of a bed of randomly placed spherical particles was adapted to allow us to define the Maximum Packing Fraction for any bimodal system. This method can be used for any ratio of particle diameter and volume Fraction for the two populations provided one has knowledge of the critical volume Fractions of related monodisperse latices (see Pishvaei et al., 2005. Polymer 46, 1235–1244). The model was tested experimentally, and rheological tests allowed us to validate the values of the critical volume Fraction ( φ c ) of different bimodal latices. A master curve of viscosity vs. polymer concentration was obtained using the concept of reduced volume Fraction. The results prove that we can predict the viscosity of multimodal systems from the knowledge of monomodal Packing Fraction.

  • rheological behaviour of polystyrene latex near the Maximum Packing Fraction of particles
    Polymer, 2005
    Co-Authors: M Pishvaei, C Graillat, Timothy F L Mckenna, Philippe Cassagnau
    Abstract:

    Abstract Additional developments in the comprehension of the rheological behaviour of polymer latices, especially near the high critical concentration ϕ c , are presented for two polystyrene latices of average particle diameters close to 200 nm with different electrostatic properties. Not surprisingly, there is a rapid transition in the rheological characteristics over a narrow range of polymer volume Fractions as the concentration of the disperse phase increases. By examining twelve different polymer volume Fractions a unique value of the critical volume concentration, ϕ c , was found for each latex. At this point, the steady shear viscosity, dynamic modulus, and dynamic shear viscosity change dramatically. Furthermore, these critical concentrations are well confirmed by the percolation theory for the dynamic zero shear viscosity as a function of volume Fraction. The Cox–Merz rule is not obeyed by these dispersions at the concentrations greater than ϕ c . By using a controlled strain Couette rheometer with a gap of 1.2 mm, shear thickening limits were also observed for both latices. The concentration dependence of the onset shear rate for shear thickening changes near ϕ c for each of the two latices.

Philippe Cassagnau - One of the best experts on this subject based on the ideXlab platform.

  • modelling the zero shear viscosity of bimodal high solid content latex calculation of the Maximum Packing Fraction
    Chemical Engineering Science, 2006
    Co-Authors: M Pishvaei, C Graillat, Philippe Cassagnau, Timothy F L Mckenna
    Abstract:

    Abstract Different rheological tests were performed on monodisperse polystyrene latices and mixtures of two different latices with different particle sizes. A critical volume Fraction φ c was defined for each of the latices. Subsequently, a method based on the estimation of the porosity of a bed of randomly placed spherical particles was adapted to allow us to define the Maximum Packing Fraction for any bimodal system. This method can be used for any ratio of particle diameter and volume Fraction for the two populations provided one has knowledge of the critical volume Fractions of related monodisperse latices (see Pishvaei et al., 2005. Polymer 46, 1235–1244). The model was tested experimentally, and rheological tests allowed us to validate the values of the critical volume Fraction ( φ c ) of different bimodal latices. A master curve of viscosity vs. polymer concentration was obtained using the concept of reduced volume Fraction. The results prove that we can predict the viscosity of multimodal systems from the knowledge of monomodal Packing Fraction.

  • rheological behaviour of polystyrene latex near the Maximum Packing Fraction of particles
    Polymer, 2005
    Co-Authors: M Pishvaei, C Graillat, Timothy F L Mckenna, Philippe Cassagnau
    Abstract:

    Abstract Additional developments in the comprehension of the rheological behaviour of polymer latices, especially near the high critical concentration ϕ c , are presented for two polystyrene latices of average particle diameters close to 200 nm with different electrostatic properties. Not surprisingly, there is a rapid transition in the rheological characteristics over a narrow range of polymer volume Fractions as the concentration of the disperse phase increases. By examining twelve different polymer volume Fractions a unique value of the critical volume concentration, ϕ c , was found for each latex. At this point, the steady shear viscosity, dynamic modulus, and dynamic shear viscosity change dramatically. Furthermore, these critical concentrations are well confirmed by the percolation theory for the dynamic zero shear viscosity as a function of volume Fraction. The Cox–Merz rule is not obeyed by these dispersions at the concentrations greater than ϕ c . By using a controlled strain Couette rheometer with a gap of 1.2 mm, shear thickening limits were also observed for both latices. The concentration dependence of the onset shear rate for shear thickening changes near ϕ c for each of the two latices.

Timothy F L Mckenna - One of the best experts on this subject based on the ideXlab platform.

  • modelling the zero shear viscosity of bimodal high solid content latex calculation of the Maximum Packing Fraction
    Chemical Engineering Science, 2006
    Co-Authors: M Pishvaei, C Graillat, Philippe Cassagnau, Timothy F L Mckenna
    Abstract:

    Abstract Different rheological tests were performed on monodisperse polystyrene latices and mixtures of two different latices with different particle sizes. A critical volume Fraction φ c was defined for each of the latices. Subsequently, a method based on the estimation of the porosity of a bed of randomly placed spherical particles was adapted to allow us to define the Maximum Packing Fraction for any bimodal system. This method can be used for any ratio of particle diameter and volume Fraction for the two populations provided one has knowledge of the critical volume Fractions of related monodisperse latices (see Pishvaei et al., 2005. Polymer 46, 1235–1244). The model was tested experimentally, and rheological tests allowed us to validate the values of the critical volume Fraction ( φ c ) of different bimodal latices. A master curve of viscosity vs. polymer concentration was obtained using the concept of reduced volume Fraction. The results prove that we can predict the viscosity of multimodal systems from the knowledge of monomodal Packing Fraction.

  • rheological behaviour of polystyrene latex near the Maximum Packing Fraction of particles
    Polymer, 2005
    Co-Authors: M Pishvaei, C Graillat, Timothy F L Mckenna, Philippe Cassagnau
    Abstract:

    Abstract Additional developments in the comprehension of the rheological behaviour of polymer latices, especially near the high critical concentration ϕ c , are presented for two polystyrene latices of average particle diameters close to 200 nm with different electrostatic properties. Not surprisingly, there is a rapid transition in the rheological characteristics over a narrow range of polymer volume Fractions as the concentration of the disperse phase increases. By examining twelve different polymer volume Fractions a unique value of the critical volume concentration, ϕ c , was found for each latex. At this point, the steady shear viscosity, dynamic modulus, and dynamic shear viscosity change dramatically. Furthermore, these critical concentrations are well confirmed by the percolation theory for the dynamic zero shear viscosity as a function of volume Fraction. The Cox–Merz rule is not obeyed by these dispersions at the concentrations greater than ϕ c . By using a controlled strain Couette rheometer with a gap of 1.2 mm, shear thickening limits were also observed for both latices. The concentration dependence of the onset shear rate for shear thickening changes near ϕ c for each of the two latices.

Edward Kosior - One of the best experts on this subject based on the ideXlab platform.

  • modelling of Maximum Packing Fraction for a dispersion of irregular particles
    5th International Conference on Bulk Materials Storage Handling and Transportation: Proceedings, 1995
    Co-Authors: A Chryss, A Mayadunne, S N Bhattacharya, Edward Kosior
    Abstract:

    The Maximum Packing Fraction of solids in a dispersed phase is affected by many parameters including particle size, size distribution, particle shape and particle fluid and particle-particle interaction. For a given dispersion, the particle size distribution and particle shape play a dominant role in affecting the Maximum Packing Fraction. For spherical particle Packing, significant progress has been made in modelling the relationship between particle size, distribution and the Maximum Packing Fraction. However, most industrial materials are not spherical in nature. The important aspect of this work has been to extend the work of Ouchiyame and Tanaka to predict Maximum Packing Fraction for spherical particles in a poly disperse system. This new model can further be used to obtain the optimum distribution of irregular shape particles in a fluid matrix as well as in dry Packing in order to maximise the Packing Fraction, provided particle shape factor and monodisperse Maximum Packing Fraction are known. Experimental measurements of Maximum Packing Fraction have been made by rheological techniques with various industrial materials and compared with the model prediction.

Hjh Jos Brouwers - One of the best experts on this subject based on the ideXlab platform.

  • particle size distribution and Packing Fraction of geometric random Packings
    Physical Review E, 2006
    Co-Authors: Hjh Jos Brouwers
    Abstract:

    This paper addresses the geometric random Packing and void Fraction of polydisperse particles. It is demonstrated that the bimodal Packing can be transformed into a continuous particle-size distribution of the power law type. It follows that a Maximum Packing Fraction of particles is obtained when the exponent (distribution modulus) of the power law function is zero, which is to say, the cumulative finer Fraction is a logarithmic function of the particle size. For Maximum geometric Packings composed of sieve Fractions or of discretely sized particles, the distribution modulus is positive (typically 0Packing Fraction of the polydisperse power law Packing, and which is governed by the distribution exponent, size width, mode of Packing, and particle shape only. For a number of particle shapes and their Packing modes (close, loose), these parameters are given. The analytical expression of the Packing Fraction is thoroughly compared with experiments reported in the literature, and good agreement is found.