Browsing by Author "Ghosal, Arkaprovo"

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Modeling of spunbond formation process of polymer nonwovens
(Elsiever, 2020-01) Ghosal, Arkaprovo
Spunbond process used in nonwoven manufacturing employs the system which combines fiber-forming and bonding together. A high molecular weight polymer, e.g., PP (polypropylene), can be used as a raw material resulting in fibers of 15–35 μm in diameter formed by the spunbond process. The present work aims at simulations of the spunbond process before the bonding stage with a goal of predicting the resulting nonwoven laydown and its three-dimensional architecture, and potentially in future, the corresponding laydown properties. The quasi-one-dimensional equations of fiber dynamics are used as a key element of the multi-fiber modeling. The air flow field is comprised of a section with one-dimensional flow used for stretching and a subsequent section with three-dimensional axisymmetric flow used for fiber deposition. The fiber motion in air flux shaped by the surrounding attenuator is simulated accounting for polymer melt quenching and solidification. The laydown properties, such as the 3-D structure of the web, mass distribution, elevation distribution and fabric cross-sectional structure, are also predicted using post-processing of the numerical results.
Modeling Polymer Crystallization Kinetics in the Meltblowing Process
(ACS, 2020-12-06) Ghosal, Arkaprovo
A novel model of the crystallization process in meltblowing process is proposed and implemented in numerical simulations. The spinline crystallization is studied using numerical solutions of the system of coupled quasi-one-dimensional equations describing the dynamics of multiple polymer jets moving in the surrounding high-speed air. Cooling, crystallization, and solidification accompany three-dimensional motion of polymer jets resulting in their vigorous stretching by the air flux including the aerodynamically driven bending/flapping. The numerical solutions predict distribution of the degree of crystallinity in polymer jets in flight, as well as in the laydown formed on the collecting screen, with the three-dimensional structure of the laydown being fully reconstructed. The effect of the collector screen temperature, die-to-collector distance (DCD), and the activation energy of the viscous flow in the polymer melt on the laydown features is studied in detail.
Numerical modeling and experimental study of solution-blown nonwovens formed on a rotating drum
(Elsiever, 2016-11-22) Ghosal, Arkaprovo
In this work the three-dimensional architecture and properties of solution-blown laydown formed on a rotating drum are studied using the system of quasi-one-dimensional equations of the dynamics of free liquid polymer viscoelastic jets moving, evaporating and solidifying, while being driven by a surrounding high-speed air jet. Solution blowing of multiple polymer jets simultaneously issued from a nosepiece and collected on a rotating drum is modelled numerically. The numerical results on the volumetric porosity of nonwoven laydown are compared with the experimental data of the present work. The numerical predictions are in good agreement with the experimental data and elucidate the effect of the angular drum velocity on the mass and angular fiber distribution, as well as the volumetric porosity and permeability of the solution-blown nonwovens. It was found that instead of doing any upstream modification of the solution blowing process, the easiest way to control the laydown structure (the mass and angular fiber distribution, as well as the volumetric porosity and permeability) is to vary the angular velocity of the collecting drum.
Numerical prediction of the effect of uptake velocity on three-dimensional structure, porosity and permeability of meltblown nonwoven laydown
(Polymer, 2016) Ghosal, Arkaprovo
This work describes the first detailed model of meltblowing process which allows prediction of such integral laydown properties as thickness, porosity and permeability. Also, such laydown properties as the detailed three-dimensional micro-structure, fiber-size distribution and polymer mass distribution are predicted. The effects of the governing meltblowing parameters on the variation of all these laydown properties are accounted for, with the influence of the collector screen velocity being in focus. For this aim numerical solutions of the system of quasi-one-dimensional equations of the dynamics of free liquid polymer jets moving, cooling and solidifying when driven by surrounding air jet are constructed. Multiple polymer jets are considered simultaneously when they are deposited on a moving screen and forming a nonwoven laydown. The results reveal the three-dimensional configuration of the laydown and, in particular, its porosity and permeability, as well as elucidate the dependence of the laydown structure on the forming conditions, in particular, on the velocity of the screen motion. It is shown and explained how an increase in the velocity of the collector screen increases porosity and permeability of the meltblown nonwoven laydown.