27 августа, 2015 
Pokraskin Although, one-part systems are considerably easier to process than either two-part or multi-part adhesives, on most occasions it will be necessary to apply heat. One-part adhesives consist of low-molecular and plastified substances. In general, the base resins are phenolic resins, epoxy resins and, for the creation of high-temperature adhesives, polybenzimidazoles and polyimides.
With regard to phenolic resins and polyimides, the crosslinking process takes place in the form of polycondensation, and consequently additional pressure must be exerted on the bond-line during the setting process. Heat must also be applied in order to remove water from the bond-line, while the pressure must be higher than the water-vapor pressure at the setting temperature (i. e. generally >500 kPa).
In contrast, contact pressure is dispensable with hot-setting epoxy resins, because the setting reaction takes place as polyaddition. Only in the case of extended-surface bonds need contact pressure be applied to the adherents because, in the noncured state, these adhesives are not capable oftransferring any mechanical forces, and any deformation of the adherents may result in destruction of the bond.
4.3.3
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