25 декабря, 2015 
Pokraskin A significant point to consider when selecting an adhesive is its moisture resistance. For this reason, the technical data of an adhesive frequently lists the durability of bonds in humid environments after prolonged time periods. Normally charts are included that list the percentage of initial resistance retained by the adhesive bond over time under known humidity conditions. Many of the test standards used by adhesive manufacturers are for lap shear data and invariably grit-blasted mild steel is used as the substrate and in the case of metal-to-metal bonds, the only way moisture can enter is through the adhesive. Once separation has begun, a weak cohesion layer is formed that withstands little or no force and the joint will fail.
When plastics are the substrates, however, and the water reaches the bond interface, the adhesive and the substrate compete for absorption and the overall effect is that the complete assembly can show good humidity resistance.
Although it depends on the chemistry of each adhesive family, thermosets can generally be said to be more durable when exposed to water than thermoplastics because they have a more closed molecular structure in which the water ingress progresses more slowly.
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