Wicking properties of various polyamide nanofibrous structures with an optimized method

Abstract

In comparison with conventional structures, nanofibrous structures have unique characteristics, such as higher surface-to-volume ratios, smaller pores, and higher porosity. Their hydrophilic nature is a key characteristic for many applications. However, because of their high porosity, it is difficult to measure the hydrophilicity of nanofibrous structures with contact-angle measurements. Therefore, characterization through wicking behavior is more appropriate. The International Organization for Standardization norm on wicking needs some refining to account for the specific nature of highly porous nanofibrous structures. A refined method was used on several structures that differed in the fiber diameter and the polyamide type. The structures with the thickest nanofibers had the highest wicking rates. At equilibrium, the wicking heights of structures of different polyamide types with the same average fiber diameter followed the trend expected from their intrinsic hydrophilicity. In the initial phase, the capillary forces established the wicking behavior. Later in the process, the wicking behavior was determined by the capillary forces and the hydrophilicity. In conclusion, the hydrophilicity of nanofibrous structures can be successfully determined by an optimized wicking procedure, and the fiber diameter is the dominant parameter for the resulting wicking height at equilibrium.

Wetting of Hydrophilic Electrospun Mats Produced by Blending SEBS with PEO–PPO–PEO Copolymers of Different Molecular Weight

“…Figure 3b shows that the equation fitted well to the wicking behavior of electrospun mats considering the whole experiment, as previously reported 6,7 . The differences in wicking rate described before are easier to observe.…”

“…The latter have been used to determine the contact angle of electrospun mats indirectly 5 , or to compare the wicking rate of spunbond and electrospun fibers 7 , mats of the same polymer with different fiber diameter 6 or mats containing two types of fibers independently co-electrospun 4 .…”

Fabric Nanocomposite Resistance Temperature Detector

“…A World Precision Instruments Inc. (U.S.A.) SP101I syringe pump and a Gamma High Voltage Research (U.S.A.) ES30P-5W voltage source were used. The fibers were spun using a 20% by weight solution of nylon-6 in a 1:1 by weight mixture of formic and acetic acid [17]. The syringe pump flow rate was 9.1-microliters per minute.…”

“…This makes it sufficiently tough and durable for use as the sensor substrate. As nylon is also used in some clothing, it is easily spun or woven and altered to fit the size and shape of the desired testing area, and the high surface area and hydrophilicity of nylon nanofibers make it an excellent fabric for use at the surface of the skin [17].…”

Effect of the relative humidity on the fibre morphology of polyamide 4.6 and polyamide 6.9 nanofibres

“…Since polyamides (PA) are known as polymers sensitive to variations in the humidity, this polymer type is selected. Focus is given to two different PA's, PA 4.6 and PA 6.9, the latter having a significantly lower hydrophilicity [20]. This varying affinity for water may result in a different electrospinning behaviour depending on the RH.…”