Adhesion promoters, analysis

By means of OH- and COOH-containing plasma polymer layers the quahfica-tion of these layers as models of single-type functionalized adhesion promoters with variable concentrations of functional groups should be proved. The plasma-initiated copolymerization of acrylic acid with ethylene or 1,3-butadiene is shown in terms of measured COOH concentration as a function of the composition of the comonomer mixture in Fig. 18.3. Depending on the co-monomer reactivity, a more linear correlation (butadiene), or a parabolic behavior (ethylene), between precursor composition and COOH groups produced was observed. For each type and concentration of functional group, its concentration was determined by chemical derivatization followed by XPS analysis as described in Section 18.2.5. 

ESCA was found to be useful in studying the effects of different methods of curing, the adhesion promoter and the deposition of copper on polyamic acid-polyimide surfaces. The results show different C Is spectral features for hot plate vs. oven cured films but identical stoichiometries. The silane treated amic acid surface showed an additional N Is component at 402.0 eV due to NH . Heat treatment of this film resulted in the formation of a silicon-polyimide. Grazing angle ESCA results showed that the silane diffused into the sub-surface of the amic-acid film. Analysis of cured polyimide films after the etch (FeCl ) removal of a... 

There are relatively few well-documented examples of interfacial primary bonding in the literature but it is possible to find examples in the areas of organic coatings on steel, metallized plastics and adhesion promoters. As the following examples will show, the exact definition of the chemistry resulting from primary bond formation at the interface has only become possible with the advent of surface analysis techniques. Such investigations rely heavily on XPS and ToF-SIMS for interfacial analysis. 

ToF-SIMS chemical imaging (often in conjunction with iXPS) also plays a role in the analysis of the interphase region of fully fabricated glass fibre composites, particularly interaction of silane based adhesion promoters with the resin matrix. ToF-SIMS is profitably used in the packaging industry (adhesives) and food industry (contamination of contents by the packaging). The technique allows examining phase-separation of blends in the surface [822]. 

The use of organofunctional silanes as adhesion promoters is well documented [90], and much is now known about their mode of operation [91], Surface analysis has played, and continues to play, an important role in the understanding of the action of these complex materials, which have been. studied on glass, and on steel and other metals. There is now general agreement that the... 

The electrochemical deposition approach was initially used for depositing orga-nofunctional silane sol-gel films for promoting adhesion between aluminum alloy and epoxy resin [Ij. Later, it was used for preparing silane films for corrosion protection of metals, electrochemical stripping analysis of metal ions, and microextraction of organic compounds [18,20,22,42,45]. The recent development of the electrochemical deposition of sol-gel-based composite films opens various applications such as encapsulating proteins, enzymes, and bacteria. In this section, we will show three main applications of eiectrodeposited sol-gel films, that is, corrosion protection and adhesion promotion, electrochemical sensors, and finally biocomposite films. Other applications such as solid-phase microextraction (SPME), nonlinear optics, antireflection, electrocatalysis, and superhydrophobic films are also discussed. 

D. Markgraf, Analysis of New Flame Treatment Technology for Surface Modification and Adhesion Promotion , TAPPI PLACE Conference Proceedings, TAPPI Press, September, 2004. 

The above analysis applies to degradation processes that relate to the bulk adhesive. Interfacial degradation processes such as corrosion can be similarly determined. Thermal and oxidative stability, as well as corrosion and water resistance, depends on the adherend surface as well as on the adhesive itself. Epoxy-based adhesives degrade less rapidly at elevated temperatures when in contact with glass or aluminum than when in contact with copper, nickel, magnesium, or zinc. The divalent metals have a more basic oxide surface than the higher-valence metal oxides and hence serve to promote dehydrogenation reactions, which lead to anion formation and chain scission.7... 

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