Лако-красочные материалы — производство

An example ‘Compliance Spectrum’ for steel/concrete bonding was proposed by the authors some years ago(l), and this is included as an Appendix to this Book. Elements of this are incorporated within the discussion on steel/concrete bonding which may be found towards the end of Chapter 6. Elementary concepts The important factors involved in any specification […]

5.1 Introduction The importance of quality assurance in any industry is widely acknowledged. More stringent customer expectations with regard to quality, together with the realisation that continued improvements in quality are often necessary for a company to sustain good economic performance, mean that some level of quality assurance is mandatory for all those associated with […]

The use of structural adhesives requires not only essential choices between the many types available, but also a considered decision on the design approach appropriate to structures assembled with them. The simplest way forward currently could involve the following steps: Fig. 4.22. Condition of the bonded interface of unstressed double lap joints after 2 years’ […]

The main durability aspects of bonded joints may now be summarised as follows: (1) water is a particularly aggressive environment for bonded joints, especially when the bonded assembly is also subjected to conditions of relatively high (normal) stress and temperature (2) joints comprising adherends possessing high surface free energies, e. g. metals, are particularly susceptible […]

It is very sound policy to collect and examine information on joints exposed to natural weathering conditions, rather than to depend solely on laboratory experiments. It has, however, been emphasised that because so many factors can affect joint strengths, extreme care must be taken when interpreting published performance data — and particularly data from durability […]

Water has proved to be the most harmful environment for bonded joints. Problems arise because water is universally found, and the polar groups which confer adhesive properties make the adhesives inherently hydrophilic; the substrates or substrate surfaces themselves may also be hydrophilic. Experience has demonstrated that the main processes involved in the deterioration of joints […]

The durability of joints, and particularly structural adhesive joints, is generally more important than their initial strength. It has been found that the mechanical properties of a bonded joint may deteriorate upon exposure to its service environment and, further, that an interfacial locus of failure may often be found only after environmental attack. A number […]

It is apparent that the effects of moisture and heat, especially in combination with an applied stress, may have a considerable influence on bonded joint behaviour. This is because of changes in the stiffness of adhesive materials with exposure to environmental conditions, and the effect has been emphasised in previous sections. The effects of temperature […]

Fatigue and creep are intimately related, being facets of a common property of an adhesive. Thus, the adhesive’s visco-elastic response is a major determinant of the fatigue life of the joint with which it is constructed. For most applications fatigue resistance in shear is of overriding importance, and slow-cycle loading is likely to be the […]

Whilst the properties and behaviour of adhesives in bulk form are linkable to their composition, the behaviour of joints constructed with adhesives is less predictable. This is to be expected from a consideration of the factors affecting joint strength outlined earlier in the chapter. In particular, joint behaviour will be determined largely by the joint’s […]