**3. Results and Discussion**

## *3.1. Morphologies of Nanofibrous Films*

Figure 1 shows the pictures of each film and the morphologies and diameter distributions of the solution blowing spun GA, PA66 films and GA/PA66 films with various weight ratios (2/1, 1/1 and 1/2 *w*/*w*). The average diameter of pure GA fibers was over 1000.0 nm, and the average diameter of pure PA66 fibers was 223.2 nm; with the weight ratio of PA66 increased from 1:2 to 2:1, the diameters increased from 172.3 nm to 322.1 nm. It can be observed that the addition of PA66 resulted in a significant reduction in fiber diameter, thus creating a denser network structure, which could improve the water vapor barrier performance. This was probably due to the fact that the addition of PA66 reduced the viscosity of the solution and promoted the elongation of the nanofibers, resulting in a thinner diameter [12]. In a similar study of modification of gelatin by Meng et al. [22], they found the average diameter of GA/poly (lactic-co-glycolic acid) (PLGA) nanofibers also decreased with the addition of PLGA. Moreover, the pure GA fibers were straight, while after the addition of PA66, the GA/PA66 composite fibers showed a curly appearance. In addition, the usage of pure gelatin solution for spinning resulted in a large number of droplets, so the film had hard lumps, leading to low solution utilization; while after the introduction of PA66, the droplets were significantly reduced and the phenomenon of hard lump formation disappeared, making the solution utilization improve. Therefore, this indicates that the addition of PA66 led to the improvement of GA spinnability during the SBS fabrication of nanofiber films. Like other spinnable polymers, nylon may increase the viscoelasticity of the gelatin-containing precursor solution, allowing for easier fiber formation [35].
