Comparison of the Recycling Behavior of a Polypropylene Sample Aged in Air and in Marine Water.During the processing and during their lifetime, polymers are subjected to several environmental stresses-thermomechanical, photo-oxidative, etc.-that can strongly modify their chemical and molecular structure and, consequently, their morphology.  The effect of the thermomechanical degradation during the reprocessing is different.  This means that the thermomechanical degradation kinetics is larger in the less degraded samples. 
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