Interfacial tension between polymers measurement

Gramespacher H and Meissner J (1992) Interfacial tension between polymer melts measured by shear oscillations of their blends. J Rheol 36 1127-41. 

Even small amounts of reaction have been found to greatly reduce the interfacial tension between polymers. Sundararaj [35] used the breaking thread method to measure... 

Considerations and measurements of interfacial tension between polymer melts dates to the 1960s and 1970s [54 to 57]. Several different methods have been used to measure interfacial tension. Extensive use has been made of 1) the shape of drops emerging from a capillary into a second phase (falling drop) [56 to 60] and 2) thread breakage, the breakup of stationary hlaments in a second liquid phase by a capillary instability [59 to 61 ]. The latter analysis is based on the work of Tomotika [62]. Other methods have been used. 

The extensive use of the Young equation (Eq. X-18) reflects its general acceptance. Curiously, however, the equation has never been verified experimentally since surface tensions of solids are rather difficult to measure. While Fowkes and Sawyer [140] claimed verification for liquids on a fluorocarbon polymer, it is not clear that their assumptions are valid. Nucleation studies indicate that the interfacial tension between a solid and its liquid is appreciable (see Section K-3) and may not be ignored. Indirect experimental tests involve comparing the variation of the contact angle with solute concentration with separate adsorption studies [173]. 

The wetting of a polymer surface is characterized by the interfacial tension between the liquid and the surface. The contact angle at the three-phase line is a good measure of the wettability of the surface. Figure 25.5 depicts the force balance... 

Although knowledge of the interfacial tension in polymer/polymer systems can provide important information on the interfacial stmcture between polymers and, thus, can help the understanding of polymer compatibility and adhesion, reliable measurements of surface and interfacial tension were not reported until 1965 for surface tension [135,138] and 1969 for interfacial tension [127,154] because of the experimental difficulties involved due to the high polymer viscosities. Chappelar [145] obtained some preliminary values of the interfacial tension between molten polymer pairs using a thread breakup technique. The systems examined included nylon with polystyrene, nylon with polyethylene (PE), and poly(ethylene tere-phthalate) with PE the values are probably only qualitatively significant [174]. 

Anastasiadis et al. [45] investigated the compatibilizing effect of an anionically synthesized model FS-b-FYE diblock copolymer on the interfacial tension between PS and PVE model polymers as a function of the concentration of the copolymer additive. They utilized the pendant drop method [155] to measure the interfacial tension between the immiscible polymer fluids. A sharp decrease in interfacial tension was observed with the addition of small amounts of copolymer (Fig. 24),... 

Arashiro, E. Y., Demarquette, N. R. (1999). Use of the pendant drop method to measure interfacial tension between molten polymers. Materials Research, 2(1), 23-32. 

The next section describes measurements of interfacial tension and surfactant adsorption. The sections on w/c and o/c microemulsions discuss phase behavior, spectroscopic and scattering studies of polarity, pH, aggregation, droplet size, and protein solubilization. The formation of w/c microemulsions, which has been achieved only recently [19, 20], offers new opportunities in protein and polymer chemistry, separation science, reaction engineering, environmental science for waste minimization and treatment, and materials science. Recently, kinetically stable w/c emulsions have been formed for water volume percentages from 10 to 75, as described below. Stabilization and flocculation of w/c and o/c emulsions are characterized as a function of the surfactant adsorption and the solvation of the C02-philic group of the surfactant. The last two sections describe phase transfer reactions between lipophiles and hydrophiles in w/c microemulsions and emulsions and in situ mechanistic studies of dispersion polymerization. 

Interfacial tension measurement techniques can be divided into two categories equilibrium and transient methods [41]. The pendent-drop method is the most commonly applied method to measure interfadal tension under pressure and involves the measurement of density differences between two fluids and the equilibrium drop profile shape. In the following section, examples of interfacial tension reduction are presented for binary polymer/C02 systems and for polymer blends. 

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