ADHESIVES, GLUES AND SEALANTS
The ageing of an adhesive bond is defined as the change in the quality of the adhesive bonding as a function of time and external factors that promote the change.
During the life and use of an adhesive bonding, it supports external effects like mechanical, physical and chemical that produces the phenomenon of ageing, the main objective of ageing tests is to accelerate and simulate these effects in order to observe and predict the behavior of the adhesive bond and propose solutions if necessary.
The effects that produce the ageing phenomenon in adhesives and in adhesives joints are:
Mechanical effects such as static, cyclic or impact loads
Chemical effects such as water, acid rain, cleaning agents, atmospheric oxygen ...
Physical effects such as temperature, ultraviolet radiation …
During the design phase, it has to be mentioned all the external factors that can affect the adhesive bond and can produce ageing in the joint, in order to perform ageing tests with combination of external factors, to predict the future behavior of the adhesive joint.
Among the most widely used aging testing we can include:
Poultice or Cataplasm - the specimen is immersed in water for some time, to simulate condensation and water leaks or high humidity that can support the joint.
Exposure to cyclic environmental conditions - is to subject the specimen for a specified number of hours to a certain range of temperature and humidity, this operation is repeated cyclically changing temperature and humidity ranges.
Exposure to chemicals - is to subject the specimen with a defined temperature and humidity, at a concentration of chemical agents that may affect the adhesive, the substrate or both, such as exposure to salts, acids, cleaning agents ...
Once ageing tests has done, we proceed to inspect or breaking the specimen using destructive methods or non-destructive methods, based on the information to be obtained, in order to get the conclusions of the behavior of the adhesive joint.
There are several rules which specify the conditions of ageing and the type of test performed, we can cite:
DIN EN ISO 9142
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