Disadvantages of adhesives

Earlier disadvantages of adhesives such as brittleness, poor water resistance, blooming around the applied adhesive, or unpleasant odors have now been remedied to a considerable degree. 

Table 13J2 Advantages and disadvantages of adhesive bonding...

One of the disadvantages of adhesive bonding is its low thermal conductivity it is thus advisable to explore the temperature distributions on the bonded tool tips as compared to the brazed one, using an infrared camera. These tests were carried out under the following cutting conditions down-milling operation with no coolant, with a depth of cut 7 mm, width of cut 10 mm, feed rate 21-082 mm/min, and spindle speed 845 rpm. The temperature distribution on the brazed tool corresponds to a temperature of 68 C, while that on the bonded tool ranges between 87 and 96°C. This indicates that for the bonded tool the heat is concentrated in the tool tip. It can thus be concluded that under severe... 

Industrial processing of adhesives has made considerable progress from the crude processes of the past [1]. Unfortunately, one of the disadvantages of adhesive bonding as an assembly method is that a bond area cannot be inspected visually. Inspection must be carried out by two methods destructive and nondestructive. Destructive inspection may be carried out on process-control test specimens prepared from the same adherend and adhesive materials as used for the production parts. The process-control specimen, as the name implies, accompanies the production parts throughout the stages of cleaning, assembly, and cure. The adhesives and adherends are all assembled at the same time and cured in the same press or autoclave. 

Adhesive bonding of glass parts is a very fast, simple and inexpensive joining technique. It can be used to join glasses to all materials and is very flexible [341]. However, the disadvantage of adhesive bonding is the necessity of an additional material, i.e. the adhesive which often results in a low thermal and chemical stability of the bond. Furthermore, adhesive joints tend to have limited long term stability. 

Although insulators other than aluminum oxide have been tried, aluminum is still used almost universally because it is easy to evaporate and forms a limiting oxide layer of high uniformity. To be restricted, therefore, to adsorption of molecules on aluminum oxide might seem like a disadvantage of the technique, but aluminum oxide is very important in many technical fields. Many catalysts are supported on alumina in various forms, as are sensors, and in addition the properties of the oxide film on aluminum metal are of the greatest interest in adhesion and protection. 

Although the acrylate adhesives are readily available and studies have shown that they can produce reasonable bonding properties, they have the disadvantages of having high shrinkage, high fluid absorption, and low service temperatures. Acrylate adhesive applications would be limited. The development of EB-curable epoxy adhesives would have applications in the aerospace and automotive industry and potential wider uses. The most immediate application for these resin systems is composite repair of commercial and military aircraft. 

Advantages and disadvantages of PMDI compared to other adhesives, especially UF-resins... 

Cements based on phytic add set more quickly than their glass polyalkenoate or dental silicate cement cormterparts, but have similar mechanical properties (Table 8.2). They are unique among add-base cements in being impervious to acid attack at pH = 2-7. Unfortunately, they share with the dental silicate cement the disadvantage of not adhering to dentine. They do bond to enamel but this is by micromechanical attachment - the cement etches enamel - and not by molecular bonding. Lack of adhesive property is a grave weakness in a modern dental or bone... 

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