Reliability and prediction of long-term performance of polymer-based materials

Abstract

The prediction of long-term performance from short-term tests is the bottom line of polymer science and engineering for users of polymer-based materials (PBMs) - which means for scientists, engineers, and laymen, or, literally, for everybody. Methods of prediction of mechanical properties (creep, stress relaxation, dynamic mechanical behavior, tension, etc.) based on the chain relaxation capability (CRC), the stress-time and temperature-time correspondence principles are presented. The methods can be applied even to small amounts of experimental data (2 or 3 isotherms or 2 or 3 stress levels) and can produce much better results than the still used 1955 Williams-Landel-Ferry (WLF) equation. Successful applications of the CRC approach include multiphase systems, including polymer liquid crystal (PLC) copolymers. An extension to the tribological properties of PBMs (in particular, scratch healing) is outlined. A quantitative definition of materials brittleness was formulated in 2006; it is connected to results in both the mechanics and tribology of PBMs.