Modeling Polymer Crystallization Kinetics in the Meltblowing Process

Abstract

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.

Overview of the Fiber Dynamics during Melt Blowing

“…Uyttendaele et al 10 reported the effects of the processing conditions on the degree of PP fiber crystallization by DSC measurements. The reported degree of crystallization was approximately 0.5, which is similar to the results reported by Hegde and Bhat 122 and Ghosal et al 60 In contrast, Xiao 139 reported a crystallization degree of 0.14 for pure PP meltblown fabric. Using polarized optical microscopy, Yin et al 101 reported that fiber birefringence continued to increase when z > 4 cm, indicating that fiber crystallization occurred after the attenuation of most fibers.…”

“…Recently, this model was extended to multiple orifices, and in simulating fibrous web structures and fiber crystallization in industrial processes. 60 Chung and Kumar 61 provided a detailed study to elucidate the factors for the fiber vibration in an air jet. An initial displacement, which was not included in Entov and Yarin's quasi-one-dimensional model, 59 was added to simulate the vibration of the fiber while maintaining its straight path.…”

Polymer melting temperatures and crystallinity at different pressure applied

“…These small peaks disappear in the data obtained with the heating rate of 30°C/min due to recrystallization or crystal perfection/thickening during DSC scanning at lower heating rate 25 . Note also that the present group recently developed a novel theory of crystallization during meltblowing an spunbonding processes used for manufacturing of nonwovens relevant in the present work 27,28 …”

Drop impact onto a substrate wetted by another liquid: Corona detachment from the wall film

“…Note that the calculation of λ via Eqs. ( 39)-( 43) is similar in a sense to the calculation of the degree of crystallization in polymer crystallization processes (Yarin, 1992(Yarin, , 1993Ghosal et al, 2019).…”