Mechanical interphase

Mechanical Interphases in Epoxies as seen by Nondestructive High-Performance Brillouin Microscopy... 

Boundaries between a reactive polymer system, e.g. an epoxy, and solid substrates modify the mechanical properties of the polymer in the interface-near region. The so created interphases are of unexpected width up to several hundred pm. The recently developed Brillouin microscopy grants nondestructive access to the local mechanical properties within these interphases. It turns out that these mechanical interphases depend strongly on the kind of polymer system, the substrate material and the preparation conditions. 

Mechanical interphases at polymer-EP interfaces are of great academic interest. Additionally, they are of technical importance in the case of metal-EP interfaces. Therefore, the formation of interphases was studied in different native metal-EP systems. 

Tm) has formed with the maximum sound velocity at the Mg interface. AU of this evidence indicates that the inhibition of the curing process (70% turnover of epoxy groups for RT curing) has been partly released within the mechanical interphase. But in the case of Mg the mechanical interphase remains even after the post-curing, and the height of the interphase has increased. 

The width of the negative mechanical interphase exceeds 100 pm. What makes the results even more strange is that the minimum of the negative interphase is about 2% below the related interphase value of the RT-cured sample. It is obvious that DETA losses during post-curing due to diffusion are not able to explain a decrease in the sound velocity data below those values measured for the sample cured at RT. 

Adhesion is a consequence of the chemical or physical interaction between two surfaces, one of which is a solid and the other a liquid, temporarily more mobile. As a consequence of the way in which adhesion is achieved practically. the interface or interphase region, where the bonds responsible for adhesion occur, is buried below many im, or even mm, of solid sub.stratc and solidified (generally crosslinked) polymer. The dimensions of the interphasc region are likely to be of the order of nm at the most (unless an extended mechanical interphase is present of the type found in the adhesive bonding of anodized aluminum alloys) so that direct examination of interphase chemistry is best considered as an exercise in the analysis of a deeply buried interface. This situation is encountered frequently by those working in microelectronics and in corro,sion and oxidation research. Removal of material is invariably ac-... 

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