Effect of a nano-fibrous structure on the nanofiber mat's hydrophobicity

To improve hydrophobicity, both low surface energy and proper surface roughness are necessary. In this research, the possible surface roughening effect of PET nanofibers was applied to manipulate an appropriate surface topography for the mat composed of them while a fluorocarbon layer generated low surface energy

A review on silica aerogel-based materials for acoustic applications

Silica aerogels are popular in terms of production volume and real-world applications. Although the current market growth rate is driven exclusively by thermal insulation, aerogels may also be attractive for acoustic applications with the potential in aiding sound absorption/insulation. This paper is a summary of the acoustics related studies of silica aerogel-based products. It introduces silica aerogels, some acoustic characterization methods, and reviews systematically the available data on sound absorption/insulation of silica aerogels, polymer-silica aerogel composites, nonwoven-silica aerogel blankets, and aerogel renders/glazing. The work identifies areas where further research is required, including experimental and theoretical work on the physics of sound absorption in mesoporous materials, and more systematic and standardized evaluations of the acoustic properties of aerogel and aerogel-composites. Aside from this call to action, the opportunities and barriers for the commercialization of silica aerogel products for acoustic applications are presented

Multiple assembly strategies for silica aerogel-fiber combinations – a review

Silica aerogels have a unique structure that makes them promising materials for variable applications. However, they are brittle due to weak inter-particle necks, and also expensive. Combining aerogel with fibers can not only enhance the mechanical/insulation properties, but also reduce dust release, and ease practical application. The majority of review articles in this field have been on the aerogel/textile systems' application or on textile impregnation in silica sol utilizing the sol–gel technique, with a few papers also addressing the use of aerogel as filler. This review for the first time highlights all strategies to assemble silica aerogel with textile materials. For sol–gel approaches, the fibers can be impregnated in a silica precursor sol to form the aerogel in situ between the fibers, but the sol itself can also be spun into aerogel fibers. Other strategies employ pre-formed silica aerogel, mixed in polymer or solvent matrices/slurries, to form aerogel injected blankets, aerogel-filled material coated fibers, and aerogel-filled composite fibers. Aerogel particles-filled textile packages have also been proposed. The emerging activities on simulations of aerogel-fiber combinations are reviewed. The advantages/disadvantages of various approaches are evaluated, and the current market situation and an outlook for the future of the field are summarized

pre-treatment and fluorocarbon finishing combination

Enhancement in polyester substrates hydrophobicity was carried out by surface modification via chemical pre-treatment, UV-Ozone irradiation and fluorocarbon finishing combinations, which are referred to as CUF-process in this paper. Polyester fabrics were impregnated with different chemicals (Na2CO3, H2O2, H2O2/Na2SiO3, NaOH and CH3NH2) before UV-Ozone gases exposure to investigate the effects of these precursor surface pre-impregnation on the effectiveness of UV-Ozone modification and final super hydrophobicity formation. The changes in substrate properties were by measuring 3 M water repellency (Water/Alcohol Drop Test), water sliding angle (WSA), water contact angle (WCA), wash and abrasion fastness, air permeability, tensile strength and visual appearance of treated fiber surfaces via SEM. The results indicated the usefulness of UV-Ozone treatment for creating proper surface roughness to improve the hydrophobicity of polyester fabrics after fluorocarbon finishing, especially when the fabric was pre-treated with NaOH and H2O2 solutions. The lowest WSA value of 7.9 degrees and the highest WCA of 142.2 degrees were achieved on polyester fabrics using pre-treatment with 60 g/l NaOH and 42 ml/ H2O2 CUF-treatments. Also, the obtained highest water repellency levels and the best air permeability properties led to significant increase in the substrate hydrophobicity did not show any adverse effect on tensile properties and strength deterioration. (C) 2016 Elsevier B.V. All rights reserved

Polyester hydrophobicity enhancement via UV-Ozone irradiation, chemical pre-treatment and fluorocarbon finishing combination

Enhancement in polyester substrates hydrophobicity was carried out by surface modification via chemical pre-treatment, UV-Ozone irradiation and fluorocarbon finishing combinations, which are referred to as CUF-process in this paper. Polyester fabrics were impregnated with different chemicals (Na2CO3, H2O2, H2O2/Na2SiO3, NaOH and CH3NH2) before UV-Ozone gases exposure to investigate the effects of these precursor surface pre-impregnation on the effectiveness of UV-Ozone modification and final superhydrophobicity formation. The changes in substrate properties were by measuring 3 M water repellency (Water/Alcohol Drop Test), water sliding angle (WSA), water contact angle (WCA), wash and abrasion fastness, air permeability, tensile strength and visual appearance of treated fiber surfaces via SEM. The results indicated the usefulness of UV-Ozone treatment for creating proper surface roughness to improve the hydrophobicity of polyester fabrics after fluorocarbon finishing, especially when the fabric was pre-treated with NaOH and H2O2 solutions. The lowest WSA value of 7.9° and the highest WCA of 142.2° were achieved on polyester fabrics using pre-treatment with 60 g/l NaOH and 42 ml/l H2O2 CUF-treatments. Also, the obtained highest water repellency levels and the best air permeability properties led to significant increase in the substrate hydrophobicity did not show any adverse effect on tensile properties and strength deterioration. © 2016 Elsevier B.V