The effect of the nano-structured aerogel powder on the structural parameters, water repellency, and water vapor/air permeability of a fibrous polyester material

A water-glass-based silica aerogel was synthesized through an ambient pressure drying method and its structural parameters, hydrophobic property, and blending with a nanofibrous polyester material were investigated. The hybrid aerogel-fibrous materials were prepared using an electrospinning method and their hydrophobic and water vapor/air permeation characteristics were analyzed using the SPSS software by one-way ANOVA, Duncan, and 1-sample K-S tests. The BET and BJH analyses showed that the nanosilica aerogel has a pore size of 24 nm and a total pore volume of 3.5 m(3)/g resulted in 88.6% porosity and 0.2 g/m(3) density. The silica aerogel granules showed a high water sliding angle, whereas, the aerogel powder-coated water droplets (marbles) showed a sliding angle of as low as 5 degrees. The SEM and AFM analyses indicated the successful embedding of the aerogel powder into the nanofibrous material with an irregular beads like structure. The most aerogel content of 4 wt% in the hybrid fibrous material showed a lower mean diameter (176.2 nm) as well as a lower mean size of spaces formed between the super-fine fibers (3598.5 nm) in comparison with the fibrous material with no aerogel content. The beaded fibrous structures of the hybrid fibrous materials led to a suitable two-scale surface roughness with an improved water contact angle up to 130.1 degrees in comparison with 103.4 degrees for the one with no aerogel content. The samples surface energy was remained unchanged with 3 M water repellency of 1. Also, there was no significant difference between the water vapor permeability (WVP) of the samples according to the ANOVA tests with P-values of more than 0.05. The super-fine fibers containing 2 and 4% aerogel have a higher permeability to air in comparison to the pure super-fine fibers and the super-fine fibers containing 0.5 and 1% aerogel, which may be due to the recognized effect on the reduction of the fibers diameter as well as smaller empty spaces formed between the super-fine fibers. (C) 2016 Elsevier B.V. All rights reserved.