Measuring Surface Energy

When a designer is selecting an adhesive for a specific application, the engineering properties of the individual plastic will be considered carefully. All too often, however, the data supplied by the plastic manufacturer will include melting point, mould shrinkage, tensile modulus, hardness, dielectric properties, water absorption, density and thermal conductivity but almost never the surface energy of the plastic, which is one of the key properties required for the adhesive application engineer. 

The use of surface-tension pens is a simple technique to measure surface energy. 

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Energy of Adhesion. The iaterfacial energy between two mutually insoluble saturated Hquids, A and B, is equal to the difference in the separately measured surface energies of each phase ... 

In the same year as Kuezynski s research was published, Shaler (1949), who had done excellent work on measuring surface energies and surface tensions on solid metals, argued that surface tension must play a major part in fostering shrinkage of powder compacts during sintering his paper (Shaler 1949) led to a lively discussion, a feature of published papers in those more spacious days. 

An alternative approach to measuring surface energies is provided by the surface forces apparatus, SFA [21]. The apparatus uses surfaces of defined geometry, such... 

There are only a few and often indirect methods of measuring surface energy parameters of solids. The problems are that surfaces contaminate and that they are usually inhomogeneous. For a review see Ref. [325],... 

Although it is very difficult to measure surface energies, they may today relatively easily and reliably be calculated from first-principles [26,27], even in the cases of quite open surfaces [28]. In Fig. 2 we show the surface energies of metals in the 4d-series of the Periodic Table obtained by first-principles calculations [27]. 

Under these conditions, one may calculate the surface energy of a solid from a measurement of A l, (see the section on measuring surface energies in Chap. 4). 

The measured surface energy of the pure ethylene homopolymer (plasma power input 300 W) was 36 mj nT, which is in the range of commercial polyethylene [1]. The polar component was also near zero, which qualifies the ethylene homopolymer as a pure chain-extending component in the copolymer and confirms the appropriateness of copolymers with ethylene sequences as a model surface with a variable concentration of exclusively one type of functional group. 

Several problems exist in the application of calculated Van der Waals forces to microbial adhesions. Firstly, calculation of the relation between net attraction and distance fails at small distances (Fig. 3), and it is in the region of this primary minimum that calculations based on measured surface energies apply. Secondly, this type of calculation does not specifically include the effects of surface charges net surface charge or a mosaic of... 

For the application of this equation one has to measure surface energy (surface tension) and its dependence on electrode potential at constant activities of the different components. Precise measurements are restricted to liquid metals like mercury or gallium and their alloys. Classical experiments were made with the Lippmann electrocapillary meter. The measurement of the drop time or the drop frequency of a dropping mercury electrode is easier. 

Fig. 1. Release force of Pseudo Bamcles (Epoxy studs ) from reference surfaces versus measured surface energy. The epoxy coatings is a marine anticorrosion layer the phenyl silicone systems are typical of hard cookware coatings PDMS 1,2,3.4 are soft PDMS-based systems with different filler types and levels, typical of fouling release coatings the fluorosilicone is a trifluorpopylmethyl-dimethyl silicone elastomeric coating...

Techniques that use the Laplace equation to measure surface energy... 

Figure 6.2 A schematic diagram of the pendant-drop technique for measuring surface energies of liquids.

Contact angle (CA) measurements with deionized water were used to evaluate wetting and measure surface energies. Figure 5 shows photographs of water droplets on each of the surfaces of the VACNT films... 

Ansari, D.M. and Price, G.J. (2004) Correlation of mechanical properties of clay filled polyamide mouldings with chromatographically measured surface energies. Polymer, 45 (11), 3663-3670. 

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