Other Forms of Stress Applied to Plastics Parts

Other Forms of Stress Applied to Plastics Parts 

In addition to the static and dynamic loads applied to plastics parts described in the preceding chapters, there are a number of other forms of energy impingement on machine and structural components to which plastics react in a manner strikingly different from other materials. In order to design plastic parts intelligently it is necessary to know the difference in response and degree of response to these other forms of stress. 

The significant stresses that will be discussed are as follows  

Impact value calculated on basis of nch specimen, i.e., inch notch length 

Polyester molding compound, glass-filled Vinyl, rigid. Type II 

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It is possible with solvents of a particular composition to determine quantitatively the level of stress existing in certain TP moldings where molded-in stresses exist. The stresses need not be applied ones but can be residual (internal) stresses resulting from the molding or other forming process that was used to shape the plastic part. Solvent mixtures suitable for this type of test are available for materials such as PSs, PCs, and acrylics through resin suppliers, who can provide details. 

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