ACTUAL EXAMPLE 2
Type of Polymer : Thermosetting plastics
Name of Material : Urea-formaldehyde (UF)
Location of Use : Electrical switches, plugs and sockets
Urea-formaldehyde is a clear thermosetting resin. It is stiff, hard, tough and strong but brittle. It has good heat resistance and good electrical insulation. On the other hand, it has poor weathering behaviour as well as low acoustic resistance. It is adhesive, abrasion resistant. Besides, it is non-flammable, self-extinguishing and produces a fishy smell when it burns. It is inexpensive. Besides, its products are usually white or brightly coloured.
Why is this material used ?
As electrical fittings, the good electrical insulation property of urea-formaldehyde is very essential. Moreover, having properties of good heat resistance can get rid of danger for consumers when touching electrical fittings. Besides, urea-formaldehyde is non-flammable and self-extinguishing can provide a benefit to act as electrical fittings. It is also low in cost. Phenol- formaldehyde (PF) is a material that has similar properties as urea-formaldehyde and so is used as electrical fittings. However, it is not as common as urea-formaldehyde because it gives an unattractive appearance (often dark brown) when urea-formaldehyde is white in colour.
Disadvantages of using this material and Solution :
Although urea-formaldehyde electrical fittings are commonly used indoors, a property of poor weathering behaviour makes no urea-formaldehyde can be used outdoors. Instead, phenol-formaldehyde with good weathering property can be used though having a poor appearance.