Advantages of adhesives

The main line of development now lies with its successor, the glass-ionomer cement, which uses a similar glass, but in which phosphoric acid is replaced by poly(acrylic acid) this cement is more resistant to acid erosion and staining and has the great advantage of adhesion to tooth material. 

The ability of glass-ionomers to form a natural adhesive bond to the surface of the tooth is one of these material s most important clinical advantages. They were originally prepared from poly(acrylic acid), a substance chosen because of its use in the zinc polycarboxylate cement, a material known to adhere to the tooth surface [123]. The advantages of adhesion by these materials were apparent right from the start, when they were used for the repair of cervical erosion lesions and as pit and fissure sealants [124,125]. 

The previous discussion highlighted a number of advantages of adhesive bonding. This section will cover both advantages and disadvantages, recognizing that some of the points have already been mentioned. 

Adhesive properties are of significant importance in optimizing bond-line thickness. To take advantage of adhesive ductility, increased adhesive thickness can increase the volume of material within which energy is dissipated. Brittle adhesives normally benefit little from increased bond-line thickness ductile adhesives often perform better with slightly thicker bondlines. 

The advantages of adhesive bonding techniques for the assembly of shafts and associated components, discussed above in detail, can be summarised as follows Cracking due to excessive hoop stresses in interference-fitted parts is avoided. 

The principal advantage of adhesives is in the ability to reduce stress concentration in joints by transferring load via the whole of the bonded area, as opposed to the discrete load points introduced by bolts or spot welds. In addition, the low density of adhesives imparted by their polymeric nature makes their use in joining technology attractive to the designers of weight-efficient structures and their uptake has therefore been widespread within the aerospace industry. 

The previous discussion highlighted a number of advantages of adhesive bonding. This section... 

Other industries were at first slow to appreciate the advantages of adhesive assembly. It was looked upon merely as a means of utilising out of tolerance... 

With the wide choice available and an improved understanding of vehicle stresses, the engineer can take full advantage of adhesives and use them in an engineering role to supplement, enhance or replace the more traditional fixing techniques. 

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