Chapter 5 - Dissipative particle dynamics simulation on melt electrospinning

Abstract

Electrospinning is a highly efficient nanofiber preparation technology, which includes solution electrospinning and melt electrospinning. Melt electrospinning is considered to be safer and more economical than solution electrospinning, because melt electrospinning is environmentally friendly, low-cost, and highly efficient. Currently, researchers are always look from the perspective of engineering applications, according to test results, or microscopic images to determine whether there is a reasonable improvement on the electrospinning equipment, and whether fibers have a special material or structure. In order for further exploration of the process of electrospinning fiber falling, this chapter introduces a mesoscopic simulation method of dissipative particle dynamics (DPD) to electrospinning. Firstly, in the melt electrospinning DPD simulation system, we have studied the effect of electric field force, polymer viscosity, and polymer chain length on fiber falling speed, the speed changes of the different stages of fiber falling, the relationship between viscosity and the speed of different falling stages, the effect of spring constant to mean square end-to-end distance of molecular chain, and also the relationship between fiber diameter and the spinneret inner diameter or polymer chain length. These explorations enable us to understand the fiber falling speed, polymer chain disentanglement, and orientation from the perspective of the mesoscopic simulation. The awareness of these issues will give powerful guidance to the utilization and improvement of electrospinning. The effects of voltages and temperatures on falling speed are investigated; the same conclusions for simulation results are obtained. Secondly, in this chapter, by considering the theory and research of the decentralized force played on polymer jets and molecular chains, called the “tug of war effect,” and the vibration force field which can reduce the interaction between molecules in the polymer melt, the changing electric field was used to replace the original general static electric field to form a vibration force field in the polymer jet and control the movement of molecular chains. The mesoscopic simulation method DPD and the dynamic electrode plate experiment were used to study the electrospinning process and the product properties. Three kinds of changing electric field are discussed.