Foam Half-life Time Research Articles

Foam breakup in inlet cyclones

Foam breakup in an inlet cyclone is studied utilizing a 0.025 m diameter Foam Characterization Rig (FCR) skid. Aqueous foam is used in the experimental program utilizing Drill Foam F-450 and SI-403 with the same surfactant concentration of 0.01 vol/vol. The foam generated with Drill Foam F-450 is more stable and requires higher g-force for foam breakup than the one generated with the SI-403. The foam half life time is proposed for foam characterization, as it is easy to measure and represents a key decay characteristic of the foam.

Foaming properties of suspensions composed by β-lactoglobulin and polysaccharides, in the presence of sucrose or polyols

This study compares the effect of different combinations between β-lactoglobulin (β-lact, 1.0–1.5% w/v), a polysaccharide (carrageenan gum, CG, or locust bean gum, LBG, 0.0–0.5% w/v) and a sweetener (sucrose, maltitol or sorbitol, 0.0–0.5% w/v) on the foaming capacity and half-life time. The experimental design was defined according to a simplex centroid mixture design with a restriction of at least 1.0% w/v of β-lact in each mixture. Measurements of particle size, zeta potential, surface tension, flow curve, foaming capacity and foam half-life time were obtained. All mixtures evaluated showed a wide particle size distribution with diameters between 5.35 and 4494 nm. Mixtures containing CG presented higher values for apparent viscosity and average particle size than mixtures containing LBG, according to the gum concentration in solution. All mixtures showed negative zeta potential values (−14.27 to −40.42 mV) due to the presence of negatively charged β-lact at the pH 7. However, CG exerted a dominant effect on the zeta potential when present in the mixtures. The surface tension and foaming capacity were affected by the combined effect of the gums and sweeteners used. These molecules seemed to concentrate the protein at the interface due to the exclusion volume effect. The foam half-life time was mainly improved by the CG due to the higher bulk apparent viscosity, regardless of the sweetener used. Replacing sucrose with maltitol or sorbitol lead to comparable foam characteristics, mainly the foam capacity and foam half-life time, which confirms the potential of these polyols for sucrose replacement in model foams.

Effects of Foamers and Stabilizers on Foaming Ability and Stability of Oxidized Starch/Polyacrylic Acid Size Liquor in Foam Sizing

Foam sizing has been studied as a low-add-on technology. Foam properties of size liquor, including foaming ability and foam stability, can directly affect the quality of sized yarns. Different foamers and stabilizers were added to oxidized starch/polyacrylic acid size liquor to prepare foaming size liquor. This paper reports the foam properties of the foaming size liquor the optimized mixed proportions of foamers and stabilizers. Foaming ratio and foam half-life time were measured to characterize the foaming ability and foam stability. The experimental results revealed that foam properties of the composite foamer and stabilizer were greater than those of each individual agent. The foam properties achieved optimum levels when the ratio of lauryl sodium sulfate to dodecyl dimethyl betaine was 80:20 and the foamer concentration was 6g/L. It was also found that the composite stabilizers of dodecanol and guar gum at a ratio of 60:40 exhibited a synergistic effect, achieving optimal foam properties at a stabilizer concentration of 4g/L. Yarn properties of the foam sizing were better than those of conventional sizing at optimum conditions.

Functional surfaces produced by foam coating

This paper reports experiments on silica coating formulations that are suitable for application as a thin pigment layer with foam coating technique on a paper web. To understand the foaming properties of nanosilica dispersions, the critical micelle concentration, foam half-life time, and foam bubble size stability were determined with three different foaming agents. The results indicate that the bubble stability measurement is a useful characterization method for foam coating purposes. Pilot foam coating trials were done and the effects of the chosen foaming agents were studied on the properties of the nanosilica-coated paper. The surface hydrophilicity of silica coated paper was related not only to silica pigment, but also to the chemical nature of the foaming agent. Standard paper properties were not affected by the thin silica coating.

Identifying changes in chemical, interfacial and foam properties of β-lactoglobulin–sodium dodecyl sulphate mixtures

Techno-functional properties of proteins, such as foam stability, can be affected by the presence of low-molecular-weight surfactants. In order to understand and control the foam properties of such protein–surfactant mixtures, a thorough characterization of foam and interfacial properties needs to be supplemented by a detailed analysis of the structural changes of the protein and possible complexation with the surfactant. In this study, β-lactoglobulin (BLG) was mixed with sodium dodecyl sulphate (SDS) in different molar ratios (MRs). The foam half-life time of BLG-SDS mixtures decreased from that of pure BLG (315min at MR 0) to 44min at MR 20, which is close to the half-life of SDS at the respective concentration. With a further increase in the MR, the foam stability of the mixture increased, similar to the stability of SDS, to 250min at the highest MR (MR 100). The minimum in the foam stability curve was not reflected in the interfacial properties (Π and Ed). Π decreased and Ed increased continuously with increasing MR from values close to those of protein towards values typically found in pure surfactant solutions.The results show no clear correlation between the interfacial and foaming properties. In addition, it was shown by isothermal titration calorimetry and mass spectrometry that SDS molecules bind to the BLG. This leads to the formation of BLG-SDS complexes. These complexes have large influence on the foam properties in the mixture. The combination of analytical methods that were used give insights about protein complexation and the resulting change of foam properties of the mixture.

Effect of Variations in the Fatty Acid Chain of Oligofructose Fatty Acid Esters on Their Foaming Functionality

In this article the effect of variations in the fatty acid chain of oligofructose fatty acid esters (OFAE) on foamability and foam stability is described. First, oligofructose (OF) mono-esters containing saturated fatty acid chains ranging between C4 and C18 were studied. Additionally, a mono-ester containing a C16 mono-unsaturated fatty acid chain and a C12 di-ester were studied. Finally, to investigate the influence of the size of the hydrophilic group, commercially available sucrose esters were studied. The surface tension and surface rheological properties of air/water interfaces stabilized by the esters were determined, as well as the foaming properties of the esters, at a bulk concentration of 0.2 % (w/v). OF mono-esters with intermediate fatty acid chain lengths (C10-C16) were able to migrate quickly to the interface producing foams with small bubbles (0.4 mm), a relatively narrow bubble size distribution, and a high stability. For oligofructose mono-esters containing fatty acids C4 and C8, the bulk concentration of 0.2 % (w/v) was below the CMC, resulting in insufficient surface coverage, and low foamability and foam stability. The OF C18 mono-ester and the OF C12 di-ester were slow to migrate to the interface resulting in low foamability. Despite similar surface tension values, the foam half-life time of OFAE was higher than of the corresponding sucrose esters. OFAE gave higher surface dilatational moduli compared to sucrose esters. Based on the frequency dependence of the modulus and analysis of Lissajous plots, we propose that OFAE may be forming a soft glass at the interface.