Aqueous foams are used extensively in many fields and anionic surfactants are commonly used foaming agents. However, potential trouble may arise when they are utilized in hard water areas and/or at low temperatures. Anionic surfactants, like sodium dodecyl sulfate (SDS), may precipitate in the form of crystals when the concentration of divalent counterions such as Mg 2+ exceeds a certain limit. In an attempt to prepare ultra-stable foams containing precipitated crystals, the behaviour of SDS in water was systematically investigated as a function of surfactant concentration at different concentrations of Mg(NO3)2 prior to a study of their foam properties. We quantitatively study the conversion of surfactant micelles to crystals and the redissolution of crystals into micelles. It was found that the presence of surfactant crystals reduced the initial foam volume and foam half-life but greatly improved the long-term stability of foams. Foam studies were also conducted for the supernatant and sediment isolated from crystal dispersions so that the importance of surfactant crystals to foam stability could be established. Despite the foamability of a sediment being low, an order of magnitude increase in foam half-life was related to the coverage of bubble surfaces by surfactant crystals. Both rapid cooling and ultrasonication were shown to influence the surfactant crystal shape and size with an impact on foam properties.
An aqueous two-phase system (ATPS) is of great value in low calorie foods or oil-free cosmetics and pharmaceuticals. In contrast to the recent work on polymer/polymer ATPSs, a simple polymer/salt ATPS (polyethylene glycol/Na2SO4) was chosen to study water-in-water (w/w) emulsions stabilized by solid particles. The binodal curve and the tie lines were first determined for the mixture at room temperature. Above the binodal curve, two water-based phases coexist; the upper phase is rich in polymer, whereas the lower phase is rich in salt. Within the two-phase region, we attempted to prepare w/w emulsions with or without the addition of common emulsifiers. Ionic and nonionic surfactants, a polymer, and various solid particles (hydrophilic calcium carbonate particles of different sizes and shapes, wax microspheres) were selected, but no stable emulsion was possible. However, stable w/w emulsions of both types (polymer-in-salt and salt-in-polymer) were formed using dichlorodimethylsilane-modified nanosilica particles. Using partially hydrophobic fumed silica as the emulsifier, emulsions remained fully emulsified for over 1 year and we link the extent of hydrophobization of particles to the properties of the emulsions via contact angle measurements. Furthermore, systematic emulsion studies were conducted at different overall compositions such that changes in emulsion type and stability were mapped onto the phase diagram. Catastrophic phase inversion of emulsion type and evolution of emulsion stability were monitored along the tie lines. Importantly, stability to coalescence was found to decrease approaching conditions of phase inversion.
In this experiment, tussah fabric was dye-free printed by using tryptophan-added method. The physical and chemical properties of printed fabrics were tested and measured. The optimal process for tussah fabric dye-free printing tryptophan added has got, which was tryptophan mass fraction of 7.5 %, PHBA of 8 %, HCl of 15 %, HEC of 2.5 %, and H2O2 of 2 %. The tussah silk fabric squeegee performed twice and then dried at 80°C for 30 min showed best printing result. Its printing pattern and outline were clear, and it had deep and uniform color. Meanwhile, the breaking strength of the fabric, color fastness and breathability, softness performs were well. What’s more, a short process was used, which it’s more environment-friendly and more economical.
Different color tussah fabric was got applied by dye-free coloration technology. When tussah fabric was treated with p-hydroxybenzaldehyde, red tussah fabric was obtained by coloration directly and two-step for deeper color, and brown color fabric was shown in one-bath coloration. In this paper, some phenomena showing in different processes of dye-free colorations was analyzed.
Spandex fabric is widely used with excellent elasticity. The oil (especially a silicone oil), which is used for easement of processing is difficult to be removed in the former processing, furthermore only rely on a treatment agent is very difficult to achieve the cleaning effect. This article we attempted to take advantage of a complex of anionic surfactants and a nonionic surface active agent to built Anionic / non-ionic agents, which has better foaming stability and the fabric processed has better whiteness, the capillary effect, the elastic elongation and elastic recovery compared to the fabric of the normal treatment.
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