Prediction of Polymer Service Lifetimes

A practical and accurate method for predicting the useful service life of polymers has long been sought. The need has become increasingly critical with the development of new materials and demanding applications, particularly those in which engineering plastics and composites are substituted for metals. 

The proliferation of materials gives scientists and engineers new design freedom. It also represents a considerable challenge. Before the best material for an application can be selected, the required performance properties (such as rigidity, strength, impact resistance, and creep) and the environment in which the product will operate must be defined. Then, the desired life expectancy for the product must be determined. Only then can the material selection process begin. 

Traditional evaluation procedures are generally laborious, time consuming, and expensive because they require fabrication of prototype parts and testing under actual end-use or simulated service conditions. These processes are more empirical than analytical, making the results of questionable value. The processes are generally impractical because they require months or years to produce results. 

Sichina [71] has discussed the applications of the dynamic mechanical analysis (DMA) to the prediction of polymer lifetimes and long-term performances, e.g., creep in gaskets, stress relaxation in snap-fit parts, modulus decay in composite structural beams, creep in bolted plates and heat deformation frequencies in structural parts. The ability of this system to generate master curves makes the prediction of product 

A second route is called the accelerated ageing method. It is based on a lambda measurement after storing the board for 25 weeks at 70 C, followed by the addition of a safety increment. This safety increment can be reduced, depending on the outcome 

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