Alan Giacomin | Queen's University at Kingston (original) (raw)

Papers by Alan Giacomin

Journal of Non-Newtonian Fluid Mechanics, 2015

This report is circulated to persons believed to have an active interest in the subject matter; i... more This report is circulated to persons believed to have an active interest in the subject matter; it is intended to furnish rapid communication and to stimulate comment, including corrections of possible errors.

Polymer-Plastics Technology and Engineering, 2001

Plastic pipe extrusion employs annular dies with eccentricity to compensate for gravity flow (cal... more Plastic pipe extrusion employs annular dies with eccentricity to compensate for gravity flow (called sag) in the cooling chamber. Here an algebraic analytic solution is obtained in bipolar cylindrical coordinates for power-law liquids. Dimensionless average velocity profiles around eccentric dies are provided to help plastic pipe engineers determine the needed eccentricity. In curved hose manufacture, the die centerpiece is made eccentric to cause curvature. Dimensionless radii of curvature are plotted to help curved hose manufacturers select the proper die eccentricity.

Core deflection results from an unevenly advancing melt front around long slender cores during in... more Core deflection results from an unevenly advancing melt front around long slender cores during injection molding. It is a pervasive problem in the manufacturing of long slender hollow parts, especially when they are thin-walled. Core deflection not only causes uneven wall thickness, but also affects the melt flow. In this paper, an effective 3D numerical approach is developed to simulate the flow around a cantilevered core, to calculate the uneven pressure distribution around the core, and to predict the core deflection. Moreover, the relation between volumetric flow rate and core deflection will be compared with a recent analytical solution .

When injection molding long slender hollow parts with closed ends, like test tubes, an unevenly a... more When injection molding long slender hollow parts with closed ends, like test tubes, an unevenly advancing melt front around the cores results in core deflection, a pervasive problem especially when the parts are thinwalled. Accurately predicting core deflection problems is accomplished by considering the distributed load on the core caused by the normal stress distribution acting on the cores. In this paper, the effect of fluid elasticity on core deflection is explored by incorporating melt memory into the prediction of core deflection using the upper convected Maxwell model. The Deborah number is then used to represent the dimensionless amount of elasticity. We find that melt memory significantly worsens core deflection, and we provide a chart to help practitioners predict this.

International Polymer Processing Journal of the Polymer Processing Society

Plastic pipe extrusion employs annular dies with eccentricity to compensate for gravity flow (cal... more Plastic pipe extrusion employs annular dies with eccentricity to compensate for gravity flow (called sag) in the cooling chamber. Here an algebraic analytic solution is obtained in bipolar cylindrical coordinates for power-law liquids. Dimensionless average velocity profiles around eccentric dies are provided to help plastic pipe engineers determine the needed eccentricity. In curved hose manufacture, the die centerpiece is made eccentric to cause curvature. Dimensionless radii of curvature are plotted to help curved hose manufacturers select the proper die eccentricity.

Unlike their glass reinforced counterparts, microstructure and dynamic fracture behavior of natur... more Unlike their glass reinforced counterparts, microstructure and dynamic fracture behavior of natural fiber-reinforced thermoplastics have hardly been investigated. Here, we characterize the microstructure of cellulose fiber-reinforced polypropylene and determined its effect on impact toughness.

International Polymer Processing, 2015

ABSTRACT Plastics can build-up on the die lip during extrusion. This phenomenon is called die dro... more ABSTRACT Plastics can build-up on the die lip during extrusion. This phenomenon is called die drool and can be costly for plastics producers, requiring periodic shutdowns for die cleaning. Die drool has been attributed to the cohesive fracture of the melt into a drool layer and a bulk layer. The bulk layer slips on the drool layer after fracture, resulting in heating at the slip interface, called slip heating. The heat generated through slip heating can contribute to polymer thermal degradation, and to the die drool degradation. The impact of slip heating on die temperature rise has been investigated by neglecting viscous dissipation (Gilbert and Giacomin, 2014). This work considers viscous dissipation and its importance to slip heating. We find that viscous dissipation and slip heating contribute equally to the melt temperature rise, and we conclude with a worked example showing the importance of these two heating sources during polymer processing. We also develop two sufficient conditions for the accurate use of our results, Pe << 1 and partial derivative Theta/partial derivative zeta << partial derivative(2)Theta/partial derivative zeta(2).

Journal of Non-Newtonian Fluid Mechanics, 2015

This report is circulated to persons believed to have an active interest in the subject matter; i... more This report is circulated to persons believed to have an active interest in the subject matter; it is intended to furnish rapid communication and to stimulate comment, including corrections of possible errors.

Macromolecular Theory and Simulations, 2015

The Canadian Journal of Chemical Engineering, 2015

ABSTRACT

Journal of Rheology, 2015

ABSTRACT Scitation is the online home of leading journals and conference proceedings from AIP Pub... more ABSTRACT Scitation is the online home of leading journals and conference proceedings from AIP Publishing and AIP Member Societies

Korea-Australia Rheology Journal, 2014

ABSTRACT For highly viscous fluids that slip in parallel sliding plate rheometers, we want to use... more ABSTRACT For highly viscous fluids that slip in parallel sliding plate rheometers, we want to use a slightly converging flow to suppress this wall slip. In this work, we first attack the steady shear flow of a highly viscous Newtonian fluid between two gently converging plates with no slip boundaries using the equation of motion in cylindrical coordinates, which yields no analytical solution. Then we treat the same problem using the lubrication approximation in Cartesian coordinates to yield exact, explicit solutions for dimensionless velocity, pressure and shear stress. This work deepens our understanding of a drag flow through a gently converging slit of arbitrary convergence angle. We also employ the corotational Maxwell model to explore the role of viscoelasticity in this converging shear flow. We then compare these analytical solutions to finite element calculations for both Newtonian and corotational Maxwell cases. A worked example for determining the Newtonian viscosity using a converging shear rheometer is also included. With this work, we provide the framework for exploring other constitutive equations or other boundary conditions in future work. Our results can also be used to design the linear bearings used for the parallel sliding plate rheometer (SPR). This work can also be used to evaluate the error in the shear stress that is caused by bearing misalignment and specify the parallelism tolerance for the linear bearings incorporated into a SPR.

proposed for filled polymer melts, and has the desirable feature of separating the effects of the... more proposed for filled polymer melts, and has the desirable feature of separating the effects of the filler material from the entanglement kinetics of the pure polymer. Both models are able to fit the steady shear viscosity data measured for this material. We find that both models are capable of predicting the LAOS behavior of this material, except for severe conditions.

Journal of Coatings Technology, 2001

ABSTRACT

Journal of Non-Newtonian Fluid Mechanics, 2015

This report is circulated to persons believed to have an active interest in the subject matter; i... more This report is circulated to persons believed to have an active interest in the subject matter; it is intended to furnish rapid communication and to stimulate comment, including corrections of possible errors.

Polymer-Plastics Technology and Engineering, 2001

Plastic pipe extrusion employs annular dies with eccentricity to compensate for gravity flow (cal... more Plastic pipe extrusion employs annular dies with eccentricity to compensate for gravity flow (called sag) in the cooling chamber. Here an algebraic analytic solution is obtained in bipolar cylindrical coordinates for power-law liquids. Dimensionless average velocity profiles around eccentric dies are provided to help plastic pipe engineers determine the needed eccentricity. In curved hose manufacture, the die centerpiece is made eccentric to cause curvature. Dimensionless radii of curvature are plotted to help curved hose manufacturers select the proper die eccentricity.

Core deflection results from an unevenly advancing melt front around long slender cores during in... more Core deflection results from an unevenly advancing melt front around long slender cores during injection molding. It is a pervasive problem in the manufacturing of long slender hollow parts, especially when they are thin-walled. Core deflection not only causes uneven wall thickness, but also affects the melt flow. In this paper, an effective 3D numerical approach is developed to simulate the flow around a cantilevered core, to calculate the uneven pressure distribution around the core, and to predict the core deflection. Moreover, the relation between volumetric flow rate and core deflection will be compared with a recent analytical solution .

When injection molding long slender hollow parts with closed ends, like test tubes, an unevenly a... more When injection molding long slender hollow parts with closed ends, like test tubes, an unevenly advancing melt front around the cores results in core deflection, a pervasive problem especially when the parts are thinwalled. Accurately predicting core deflection problems is accomplished by considering the distributed load on the core caused by the normal stress distribution acting on the cores. In this paper, the effect of fluid elasticity on core deflection is explored by incorporating melt memory into the prediction of core deflection using the upper convected Maxwell model. The Deborah number is then used to represent the dimensionless amount of elasticity. We find that melt memory significantly worsens core deflection, and we provide a chart to help practitioners predict this.

International Polymer Processing Journal of the Polymer Processing Society

Plastic pipe extrusion employs annular dies with eccentricity to compensate for gravity flow (cal... more Plastic pipe extrusion employs annular dies with eccentricity to compensate for gravity flow (called sag) in the cooling chamber. Here an algebraic analytic solution is obtained in bipolar cylindrical coordinates for power-law liquids. Dimensionless average velocity profiles around eccentric dies are provided to help plastic pipe engineers determine the needed eccentricity. In curved hose manufacture, the die centerpiece is made eccentric to cause curvature. Dimensionless radii of curvature are plotted to help curved hose manufacturers select the proper die eccentricity.

Unlike their glass reinforced counterparts, microstructure and dynamic fracture behavior of natur... more Unlike their glass reinforced counterparts, microstructure and dynamic fracture behavior of natural fiber-reinforced thermoplastics have hardly been investigated. Here, we characterize the microstructure of cellulose fiber-reinforced polypropylene and determined its effect on impact toughness.

International Polymer Processing, 2015

ABSTRACT Plastics can build-up on the die lip during extrusion. This phenomenon is called die dro... more ABSTRACT Plastics can build-up on the die lip during extrusion. This phenomenon is called die drool and can be costly for plastics producers, requiring periodic shutdowns for die cleaning. Die drool has been attributed to the cohesive fracture of the melt into a drool layer and a bulk layer. The bulk layer slips on the drool layer after fracture, resulting in heating at the slip interface, called slip heating. The heat generated through slip heating can contribute to polymer thermal degradation, and to the die drool degradation. The impact of slip heating on die temperature rise has been investigated by neglecting viscous dissipation (Gilbert and Giacomin, 2014). This work considers viscous dissipation and its importance to slip heating. We find that viscous dissipation and slip heating contribute equally to the melt temperature rise, and we conclude with a worked example showing the importance of these two heating sources during polymer processing. We also develop two sufficient conditions for the accurate use of our results, Pe << 1 and partial derivative Theta/partial derivative zeta << partial derivative(2)Theta/partial derivative zeta(2).

Journal of Non-Newtonian Fluid Mechanics, 2015

This report is circulated to persons believed to have an active interest in the subject matter; i... more This report is circulated to persons believed to have an active interest in the subject matter; it is intended to furnish rapid communication and to stimulate comment, including corrections of possible errors.

Macromolecular Theory and Simulations, 2015

The Canadian Journal of Chemical Engineering, 2015

ABSTRACT

Journal of Rheology, 2015

ABSTRACT Scitation is the online home of leading journals and conference proceedings from AIP Pub... more ABSTRACT Scitation is the online home of leading journals and conference proceedings from AIP Publishing and AIP Member Societies

Korea-Australia Rheology Journal, 2014

ABSTRACT For highly viscous fluids that slip in parallel sliding plate rheometers, we want to use... more ABSTRACT For highly viscous fluids that slip in parallel sliding plate rheometers, we want to use a slightly converging flow to suppress this wall slip. In this work, we first attack the steady shear flow of a highly viscous Newtonian fluid between two gently converging plates with no slip boundaries using the equation of motion in cylindrical coordinates, which yields no analytical solution. Then we treat the same problem using the lubrication approximation in Cartesian coordinates to yield exact, explicit solutions for dimensionless velocity, pressure and shear stress. This work deepens our understanding of a drag flow through a gently converging slit of arbitrary convergence angle. We also employ the corotational Maxwell model to explore the role of viscoelasticity in this converging shear flow. We then compare these analytical solutions to finite element calculations for both Newtonian and corotational Maxwell cases. A worked example for determining the Newtonian viscosity using a converging shear rheometer is also included. With this work, we provide the framework for exploring other constitutive equations or other boundary conditions in future work. Our results can also be used to design the linear bearings used for the parallel sliding plate rheometer (SPR). This work can also be used to evaluate the error in the shear stress that is caused by bearing misalignment and specify the parallelism tolerance for the linear bearings incorporated into a SPR.

proposed for filled polymer melts, and has the desirable feature of separating the effects of the... more proposed for filled polymer melts, and has the desirable feature of separating the effects of the filler material from the entanglement kinetics of the pure polymer. Both models are able to fit the steady shear viscosity data measured for this material. We find that both models are capable of predicting the LAOS behavior of this material, except for severe conditions.

Journal of Coatings Technology, 2001

ABSTRACT