Impact Behaviour of Plastics

Fortunately the situation in practice is not quite as complex as it might seem. In general, very acceptable designs are achieved by using impact data obtained under conditions which relate as closely as possible to the service conditions. Impact strength values available in the literature may be used for the initial selection of a material on the basis of a desired level of toughness. Then, wherever possible this should be backed up by tests on the plastic article, or a specimen cut from it, to ensure that the material, as moulded, is in a satisfactory state to perform its function. 

As always, of course, to alleviate fracture problems it is essential to avoid the factors which are likely to cause brittleness. These include stress concentrations and low temperatures and the effects of these will be considered in the following sections. 

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