It is worthy of note that when producing fibers from solution electrospinning, upwards of 90% of the material being electrospun will evaporate throughout the process. The evaporation of the solvent is a significant factor in the extreme reduction in diameter of electrospun fibers. This is a luxury that molten fibers do not possess. Viscosity has been shown to be one of the most crucial experimental parameters in producing electrospun fibers with smaller diameters. For the most part, polymer melts have a higher viscosity than polymer solutions and as a result, have much larger fiber diameters when electrospun. Deitzel showed that as the concentration is increased in a polymer solution, therefore increasing the viscosity, there comes a point when electrospinning is no longer possible.

However, there are certain steps that can be done to lower the viscosity of a polymer melt. It is possible to electrospin a polymer of lower molecular weight from the melt or to combine the melt with a plasticizer but these will have an adverse effect on the mechanical properties of the produced fiber so an alternative must be sought. It is an absolute necessity to have precise control on the processing temperature when electrospinning from the melt. Some polymers are more difficult to melt electrospin because a sizeable gap between the melt temperature and degradation temperature is desirable to be capable of lowering the viscosity as much as possible without having a major impact on the resultant mechanical properties.

Currently, the focus in electrospinning remains being capable of consistently producing fibers with a diameter smaller than 100 nanometers. Research has shown that at the present time, electrospinning from solution is a more effective way to continually produce nanofibers. However, this technology is not without its downfalls. Perhaps the major downfall of solution electrospinning is the production rate. Due to the evaporation of the solvent, the rate from solution electrospinning is very low. Reports show that by solution electrospinning, approximately 0.01 grams of fiber per hour are produced. Simply by choosing to electrospin from the melt the rate increases by almost an order of magnitude and the yield is increased as well. This rate is still not sufficient to be commercialized but it is a step in the right direction. Another unbecoming feature with solution electrospinning is the cost, not only monetarily but environmentally. The solvents associated with electrospinning are often very costly and in some cases dangerous to your health and the environment. Melt electrospinning eliminates both of these concerns. As more and more industries attempt to use electrospun materials, it is conceivable that the focus will be not only on producing nanoscale fibers, but doing so in the most cost effective and environmentally friendly way. It has been shown that the micrometer barrier could be crossed from melt electrospinning as shown in Figure 2.

Figure 2: Melt electrospun PET fibers

It is only a matter of time until this phenomenon can be consistently reproduced when this happens, solution electrospinning will be a procedure of the past.