Foam behavior

Examinations of the connection between the chemical structure of alkylaryl sulfates and their physical-chemical properties show that solubility, aggregations and adsorption behavior, foam behavior and consistency are determined by the following structural elements the length of the alkyl chain, the position at which the benzene ring is connected to the alkyl chain, and the substitution pattern of the benzene ring [187,188]. 

Foam behavior and foam stability are strongly dependent on the water hardness. With a water hardness of 0 ppm the foam behavior and foam stability of LAS improves as the molecular mass increases. This behavior is exactly the opposite at a water hardness of 300 ppm. From 100 ppm the optimum for the Cn homologs is obtained. With the same molecular mass, the foam consistancy of the homologs is highest when the content of 2- and 3-phenylalkanes is highest [187]. In terms of stability in hard water a higher 2-phenylalkane content has a positive influence. An increase in molecular mass has the effect of reducing the hard water stability [189-191]. 

Foaming plays an important part for many applications. Figure 8 shows foaming behavior of sulfosuccinates expressed as foam height in the Ross-Miles test. 

FIG. 8 Foaming behavior of sulfosuccinates—Ross-Miles method. 

Monoamidotriphosphate compounds have been evaluated for their combined detergent-sequestrant action [65,66]. Good surfactant properties are also attributed to organoaminodialkylenephosphonic acids. Typical compounds of this kind are the tetra- and trialkali salts of decyl-, dodecyl-, and tetradecylaminodi (methylphosphonate). Values of surface tension and detergency are given in Refs. 118 and 216-219. Wash test results, foam behavior, wetting performance, and surface tensions of aqueous solutions of phosphate esters have been tabulated [12,17,18,33,37,50,52,56,90,220]. 

Salts of alkyl phosphates and types of other surfactants used as emulsifiers and dispersing agents in polymer dispersions are discussed with respect to the preparation of polymer dispersions for use in the manufactoring and finishing of textiles. Seven examples are presented to demonstrate the significance of surfactants on the properties, e.g., sedimentation, wetting behavior, hydrophilic characteristics, foaming behavior, metal adhesion, and viscosity, of polymer dispersions used in the textile industry [239]. 

The physical properties important for the projected use of hydraulic fluids are viscosity, density, foaming behavior, and fire resistance. There is no generally recognized test method for measuring flammability of hydraulic fluids, although various test methods maybe utilized (Moller 1989). 

The basis for the foam properties is given by interfacial parameters. Although correlations have been shown between a single parameter and foam properties, there is still a lack in a general correlation between interfacial properties and the foam behavior of complex systems in detergency. The simplest approach to correlate interfacial parameters to foam properties is the comparison of the surface activity measured by the surface tension of a surfactant system and foam stability. 

Alkyl polyglucoside carboxylate (INCI-name Sodium Lauryl Glucose Carboxylate (and) Lauryl Glucoside, Plantapon LGC SORB) is a new anionic surfactant with excellent performance for personal care cleansing applications. In shampoo and shower bath formulations the anionic surfactant shows a good foaming behavior. In body wash applications it improves sensorial effects. These properties make Plantapon LGC SORB suitable for several cosmetic applications, e.g., mild facial wash gel, mild baby shampoo, mild body wash for sensitive skin, wet wipes, and special sulfate-free shampoo applications. 

In the beer industry, foaming behavior is vital to the product. The beer bottle is produced under C02 gas at high pressure. As soon as a beer bottle is opened, the pressure drops and the gas (CO2) is released, which gives rise to foaming. Commonly, the foam stays inside the bottle. Foaming is caused by the presence of different amphiphilic molecules (fatty acids, lipids, and proteins). The foam is very rich as the liquid film is very thick and contains a substantial aqueous phase (such foams are... 

Spatiael et al. [77] studied the foaming behaviors of several TPV formulations containing various amounts of branched PP resin with water as the blowing agent, while the extensional viscosity of the materials with different formulations was measured and considered. The authors indicated that the replacement of a small amount of linear PP with branched PP improved the foam density and cellular structure. However, as the added content of branched PP was increased, a worse foamability was observed. They concluded that there exists an optimal amount of... 

K. Kalischewski, W. Bumbullis and K. Schugerl, Foam behavior of biological media, I, Protein foams, Eur. J. Appl. Microbiol. Biotechnol. 7(1979)21-31. 

Correlation of the Micro structure and Nanostructure to the Foaming Behavior 241... 

In search of easy dispersible nucleating agents with a high number of nucleants per volume, Spitael et al. [19] investigated the use of nanoscale diblock copolymer micelles on the batch-foaming behavior of PS. The diblock copolymers were composed of a PS block, and either PDMS, PEP, or PMMA as a second block. Several factors were identified as essential for nucleation, e.g., the size of the micelle and the surface tension of the micelle core material. 

Microcellular foaming, bimodal cell size distributions, and high open-celled contents of molecular composites of HT-polymers were reported by Sun et al. [33], investigating blends of a rod-like polymer polybenzimidazole with an aminated PSU and poly(phenyl sulfone) by using carbon dioxide as a blowing agent. The complex foaming behavior was related to phase separation within the otherwise... 

Despite the formidable chances to develop and to tailor cellular polymers, the literature describing the foaming behavior of blends is still rare. Critically analyzing the existing studies, only a few publications systematically discuss the following phenomena ... 

Correlation between blend morphology, melt-elongation, and foaming behavior — despite the significant influence only addressed for neat polymers [38], miscible blends [4, 5], and some filled systems [39,40]... 

Fig. 4 General strategy for understanding and controlling the foaming behavior of blends...

Besides the blend morphology and the rheological behavior, the solubility of the blowing agent is regarded as key criteria for the foaming behavior. As can be seen in Fig. 8, both neat components reveal a high affinity towards carbon dioxide, as a... 

In the present case, the foam density relates perfectly with the previously observed rheological properties, as a transition in the flow behavior was detected at approximately 20 wt% of PPE (Fig. 13). In the viscoelastic case (below the percolation limit), the PPE content neither significantly influences the foamability nor the blend rheology. At elevated contents (beyond percolation), however, the PPE content strongly affects the rheological response of the blend and, subsequently, degrades the foaming behavior, which is verified by a reduced expandability. 

The fundamental relationships between compatibilization and selective blending on the blend characteristics and the foaming behavior, as demonstrated in the following, will not only be valid for this particular blend system, but will help to understand and control the foaming behavior of multiphase polymer blends in general. 

Fig. 14 Potential strategies for enhancing the foaming behavior of immiscible blends...

The aim of this section, therefore, is to correlate systematically the compatibilization of PPE/SAN 60/40 blends by SBM triblock terpolymers with the foaming behavior of the resulting blend. The reduction of the blend phase size, the improved phase adhesion, a potentially higher nucleation activity of the nanostructured interfaces, and the possibility to adjust the glass transitional behavior between PPE and SAN, they all promise to enhance the foam processing of PPE/SAN blends. 

As a next step, the effect of compatibilization on the foaming behavior will be discussed. While the density can only be slightly reduced by SBM, and remains at a rather high level, the foam structure reveals distinct differences, exemplarily shown for a foaming temperature of 160°C and at a foaming time of 10 s (Fig. 18). As mentioned earlier, the uncompatibilized blend reveals a highly inhomogeneous structure,... 

As previously shown for PPE/SAN blends, the foaming behavior of immiscible blend systems is affected by both the properties of the blend phases and the overall blend structure [1], In the present blend system, the viscosity of one specific blend phase is varied as a result, not only the foaming behavior of the blend phase is altered but also the microstructure of the blend is affected [94]. By investigating blend systems with constant PPE to PS ratios of 75/25 and 50/50, and varying the SAN content in the range of 20-40 wt%, the influence of both the microstructure and the viscosity ratio can be analyzed (Table 3). 

In order to understand the highlighted foaming behavior, both the blend morphology and the properties of the individual blend phases need to be taken into account. On the one hand, the less viscous, lower Tg SAN phase reveals a higher tendency to nucleate foam cells, both by homogeneous nucleation within the SAN phase and by heterogeneous nucleation at the interface to PPE/PS. Furthermore, the lower viscosity of the SAN phase promotes rapid cell growth and expansion. As a result of the... 

By foaming an immiscible blend system of a poly(ethylene glycol)PEG/ polystyrene (PEG/PS), Taki et al. detected a similar foaming behavior as well as a bimodal cell size distribution [78], While smaller cells formed in the more... 

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