Surface energy polar component

Both treatments, in air and nitrogen plasma, increased the surface energy of the PE film to the same level after 20 s. After one minute of treatment, the surface energy polar component of the nitrogen-treated PE is much higher (12mN/m) than that of the air plasma-treated PE (7mN/m). This eonfirms the XPS results presented above [115]. 

Polymer Surface energy, total, mJ/m Surface energy, dispersion component, mJ/m Surfaee energy, polar component, mJ/m ... 

Overall Surface Energy Polar Surface Energy Component... 

Surface tension of polymers can be divided into two components polar (y ) and dispersion (7 ), to account for the type of attraction forces at the interfaces. Chemical constitution of the surface determines the relative contribution of each component to the surface tension. Polar component is comprised of various polar molecular interactions, including hydrogen bonding, dipole energy, and induction energy, whereas the dispersion component arises from London dispersion attractions. The attractive forces (van der Waals and London dispersion) are additive, which results in the surface tension components being additive 7 = 7 + 7 . 

Geometric mean approximation Dispersive and polar components of solid surface energy are found by solving yiv(l +COS0) = 2(y,Xf + 2(y Yl S An extension of GGF equation ysa predicted is significantly higher than the critical surface tension. [84]... 

These equations result from assuming that the total surface energy can be split into the sum of components associated with different types of bonding, for example dispersion plus polar yP (Eqs. 14 and 15), or Lifshitz-van der Waals... 

The work of adhesion between a PSA and a release coating can be expressed in terms of the dispersive and polar components of the surface energies of the PSA and release coating [8]. 

Typically, the polar surface energy component of polymers used for release coatings is relatively small and the work of adhesion can be written simply as... 

Measurement of the contact angle at a solid-liquid interface is a widely used method for the determination of the surface energy of solid polymers. Fowkes [1] first proposed that the surface energy of a pure phase, y y could be represented by the sum of the contribution from different types of force components, especially the dispersion and the polar components, such that ... 

The polar and dispersion components of the surface energy are generally obtained using two liquids, for example water and formamide. To calculate yf and y/, the following values for y/ and yf were taken [3] ... 

It is known that the possible interaction between two materials 1 and 2 is determined by their surface energies, which consist of two components, dispersive, and specific or polar, y . When hydrogen bonding and acid-base interactions are also involved, the adhesion energy between the two materials, Wa will be" ... 

Treatment with fluorine/nitrogen mixtures (fluorination) increases the polar component of the surface energy initially, but longer treatment times result in a drop in both the polar component and the total surface energy24 25 (see Figure 16.3). At very long treatment times the surface energy ofthe treated surface can be lower than that of the polyolefin itself. 

The dispersive and polar components of the surface tensions of the liquids were estimated to be 7 = 21.8 mN/m and 7 = 51.0 mN/m for water and 7 = 49.5 mN/m and 7 = 1.3 mN/m for methylene iodide. This estimation was done by measuring contact angles with various hydrocarbons and assuming that there are only nonpolar interactions. What are the surface energies, 7s, of the polymers ... 

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