Formation of a nylon-6 micro/nano-fiber assembly through a low energy reactive melt spinning process

Abstract

Commercial synthetic fibers of below 10 μm in diameter are usually unachievable with conventional melt spinning technology using high molecular weight polymers as the starting materials. The electrospinning process is capable of forming nanoscale fibers but is usually accompanied by the use of 80–90 wt% organic solvents, which greatly reduces the fiber yield and increases process cost as well as causing environmental concerns. We describe herein an approach using the caprolactam monomer as the main starting material for reactive anionic polymerization, propagating the degree of polymerization to achieve suitable melt viscosity for drawing into ultra-fine fibers using an electrostatic field force. The process temperature was well below that of the nylon 6 melting point. We demonstrate that through this low energy consumption integrated process, essentially all monomers can be transformed into the final nylon-6 micro/nano fiber assemblies which was unattainable from prior industrial or research processes.