Experimental Investigation of Solution Blow Spinning Nozzle Geometry and Processing Parameters on Fiber Morphology

The solution blow spinning (SBS) technique has been used for over a decade to produce micro- and nanofibers from polymers and ceramics. Among the advantages of SBS over other fiber spinning techniques are its high polymer injection rate, which results in high fiber production output and low costs associated with the spinning setup. SBS essentially consists of the joint flow of a pressurized gas and a polymer solution through a concentric nozzle system, with the polymer being injected through the inner nozzle and the gas flowing through the outer one. Polymer properties and processing variables are of key importance to ensure fiber productivity and homogeneity. In this work, we investigate the effect of nozzle geometry (variation in the length and diameter of the outer nozzle, inner nozzle protrusion, and centralization) on the manometric pressure responsible for fiber stretching. Manometric pressure tests were carried out to evaluate the best conditions for producing thinner and more uniform fibers. To validate these experiments, polycaprolactone (PCL) and poly(lactic acid) (PLA) were spun, and fiber morphology was evaluated by scanning electron microscopy. Results show that the 0.5 mm inner nozzle protrusion and the shortest outer nozzle length (22.3 mm) as well as nozzle centralization are the best conditions with greater potential for producing thinner and more homogeneous fibers. The results demonstrate that changes in the SBS nozzle geometry directly influence the morphology of the spun fibers, with diameters ranging from 279 ± 242 to 472 ± 240 nm for PCL and 515 ± 237 to 1277 ± 370 nm for PLA. These results also show the necessity of taking into consideration not only material variables but also nozzle geometry if fibers produced from different research groups are to be fully compared.