Critical Surface Tension table

For an adhesive to wet a sohd surface, the adhesive should have a lower surface tension than the solid s critical surface tension. Tables 7.2 and 7.3 hst surface tensions of common adherends and liquids. 

The critical surface tension of Teflon is extremely low. In fact Teflon is one of the materials having among the lowest critical surface tensions (Table 6.1). Thus, Teflon is very difflcult to wet by ordinary liquids, most of which have surface tensions above 20 mN m . The wetting can be improved either by using surfactants that can lower substantially the surface tension of liquids or by special surface treatment which can increase the surface tension of Teflon, e.g. by adding polar groups, plasma treatment, etc. 

Silanes can alter the critical surface tension of a substrate in a well-defined manner. Critical surface tension is associated with the wettabiUty or release qualities of a substrate. Liquids having a surface tension below the critical surface tension, y, of a substrate wet the surface. Critical surface tensions of a number of typical surfaces are compared to y of silane-treated surfaces in Table 2 (19). 

The presence of the polar hydrogel on the surface of PET films led, as seen from Table V, to a decrease in their contact angle with water and to a corresponding rise of the critical surface tension through the polar component... 

Table V. Wetting Angle at the Contact with Water ( fa) and Formamide (- jO and Critical Surface Tension (1 ) at 20°C...

The surface properties are of particular interest for composites and coatings. The n = 6 monomer will wet Teflon, and PTFE filled composites can be prepared. The critical surface tension of wetting for the fluoromethylene cyanate ester resin series has been determined from contact-angle measurements on cured resin surfaces. As indicated in Table 2.2, it parallels the fluorine composition and begins to approach the PTFE value of 18 dyn/cm. 

The extent to which surface tension can be controlled by fluoroalkyl-containing coupling agent type treatments is summarized in Table 1. Its purpose is to simply illustrate the range of control possible detailed comparisons are unwarranted because of differences in sample preparation and choice of substrate, data acquisition and treatment. Some of the critical surface tensions (crc) are obtained with -alkanes, some with other liquids. Some of the dispersion force components (of) and polar components (of) of solid surface tension are derived by use of different equations. The reader is referred to the key references in Table 1 for full details. 

For a selection of non-polar liquids on a given solid, it follows that 0 should decrease as yLG decreases and become zero below a certain value of tlg- Zisman78 has named this value of yLG the critical surface tension, yc, for the solid. Critical surface tension is a useful parameter for characterising the wettability of solid surfaces (see Table 6.1). 

Table 6.1 Critical surface tensions for solid surfaces (After Zisman78)...

Table I. Critical surface tension of wood components (29, 30).

Table 3.4 gives an overview of critical surface tension values of different polymer surfaces [10]. From these data it is obvious that polytetrafluoro ethylene surfaces can only be wetted by specific surfactants with a very low surface tension, e.g. fluoro surfactants. 

Table 3.4 Critical surface tension of polymer solids [10] ...

Table 3.3 provides surface tensions yLV for common adhesive liquids and critical surface tension yc for various solids. A brief discussion of how these properties are measured follows. 

TABLE 3.3 Surface Tension of Several Liquids Including Epoxy Adhesive Formulations (Top) and Critical Surface Tension of Various Substrate Materials (Bottom)... 

Critical Surface Tensions. The data in Table II may be plotted (Figure 5) as cos 6 vs. yLV, according to the approach of Zisman (37). Then one may estimate the critical surface tension, yc of the undissociated polycation+-Cl surface of this particular nylon film in equilibrium with saturated water vapor by extrapolating the last four data points (which... 

Table III. Estimate of Critical Surface Tensions for Undissociated Poly R4N-X Surfaces0...

The / -( -chlorophenyl)ethylsilane Derivatives. Data on the wettability of the / - (chlorophenyl) ethylsilane films are given in Table III. These films were formed by vapor deposition as well as by adsorption from solution. Critical surface tensions of 40-45 dynes/cm. and 0H2o of 80°-86°C. were obtained by vapor deposition of the trichloro derivative at 25°C., the trimethoxy derivative at 70°C. and from a solution of the triethoxy compound with n-propylamine. These films were all water stable. The other films formed by the triethoxy and trimethoxy com-... 

In Table III, critical surface tensions of thirty-nine polymers are reported, calculated on the basis of Equation 5 by assuming < = 1. In other words, these calculated results are equivalent to the calculated solid surface tensions (y8). Solubility parameters of several polymers listed in the table were calculated on the basis of Small s constants (35), and all molar volumes were calculated on the basis of the molecular weight of the repeat unit and the density of the polymer. The results in Table III were used to prepare a graph (Figure 2) for the comparison between the calculated and the observed critical surface tensions of these polymers. The data are rather scattered, and the calculated values are generally lower than those observed directly. The following factors may be contributing to the deviations ... 

The monomers chosen for these investigations are shown in Table I. They were selected so that a range of properties changed depending on the pair selected for the synthesis of these semi-1-IPNs (34). Factors of particular interest were the water solubility of the monomers, which could influence the locus of polymerisation and the relative hydrophilicities of the homopolymers as indexed by critical surface tension. In a semi-l-IPN the first-formed polymer is a network, but the second-formed polymer is linear. 

Surface tension studies of the most common fluorosilicone, poly(3,3,3-trifluoropropylmethylsiloxane) (PTFPMS), give unexpected results. Compared with (PDMS), PTFPMS has a higher liquid surface tension, a similar critical surface tension of wetting, and a considerably lower solid surface tension, as determined by water and methylene iodide contact angles and the method of Owens and Wendt (67). These results are summarized in Table X (7, 67, 72-74, 76, 77), in which PTFPMS is compared with two other fluorocarbon polymers, poly(tetrafluoroethylene) (PTFE) and poly(chlorotrifluoroethylene) (PCTFE). PTFE behaves like PTFPMS, whereas PCTFE behaves like PDMS. 

TgS for polymers with architectures similar to PDMS are given in Table XII 21, 81). The TgS of poly(dimethylsilazane) and poly(dimethyl-silmethylene) lie between those of PDMS and poly(isobutylene) (critical surface tensions of wetting of 24 and 27 mN/m, respectively [70]). These values suggest that poly(dimethylsilazane) and poly(dimethylsilmethylene) will have critical surface tensions of wetting in the 25-26-mN/m range. 

Using contact angle measurements, Baier determined the critical surface tension of the spontaneously acquired films deposited on a clean inorganic solid placed in human mouths for periods of 30 sec, 2 min, and 15 min (14) see Table II). Concurrent determination of multiple attenuated internal refiection IR spectra of the adsorbed films provided evidence for the presence of protein material. While the spectra revealed... 

Table III. Critical Surface Tension of Wetting (Yj,) for some Photoresists (from Ref. 27, reprinted by permission of the publisher.

Table B.2 Critical surface tension of packing materials.

Table 9.1 Critical surface tension,yc, dispersion component, y%/, and surface tension, ySv, values of polymeric solids. (Values compiled from standard references especially from Kaelble, D.H. (1971) Physical Chemistry of Adhesion. Wi ley-lnterscience, New York, and Zisman, W.A. (1 964) in Contact Angle Wettability and Adhesion, Adv. Chem. Ser. No 43, American Chemical Society, Washington D.C.) ...

Table I. Critical Surface Tension of PNF as a Function of UV Irradiation...

---