Phenol-formaldehyde mouldings

It is thus seen that a phenol-formaldehyde moulding powder will contain the following ingredients ... 

Today the phenol-formaldehyde moulding compositions do not have the eminent position they held until about 1950. In some, important applications they have been replaced by other materials, thermosetting and thermoplastic, whilst they have in the past two decades found use in few new outlets. However, the general increase in standards of living for much of this period has increased the sales of many products which use phenolics and consequently the overall use of phenol-formaldehyde moulding powders has been well maintained. 

In Britain, similar experiments were being carried out by a British inventor. Sir James Swinburne, whose search for a material with good electrical properties led him to develop similar materials to Bakelite. His experiments were less complete than those of Baekeland but the two collaborated in the 1920s to develop the Bakelite business in Britain. The success of phenol-formaldehyde mouldings stimulated research into other polymers. 

Fig. 2.22 Temperature dependence of oxygen index for various plastics 1 rigid PVC, can not be measured above 105 due to softening 2 asbestos-filled phenol/form-aldehyde moulding compound 3 epoxy-modified melamine moulding compound 4 phenol/ formaldehyde moulding compound filled with wood flour 5 glass fibre-filled epoxy resin moulding...

Resins prepared from melamine, phenol and formaldehyde have found some use in the preparation of moulding powders. These materials have properties which are intermediate between those of melamine-formaldehyde and phenol-formaldehyde moulding powders. In particular, mouldings have better dry-heat dimensional stability than those based on straight melamine-formaldehyde and they may be produced in a much wider range of colours than phenol-formaldehyde mouldings. Typical applications of melamine-phenol-formaldehyde materials include domestic mouldings such as iron handles where a combination of heat resistance and decorative appeal is required. 

Figure 10.3 Flow-cure relationship for a typical phenol-formaldehyde moulding compound I Plasticization period II Injection stage III Curing process...

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