APPLICATION OF RAMAN-SPECTROSCOPY TO DETERMINE THE STRAIN-LEVEL IN POLYBUTYLENE TEREPHTHALATE (PBT)

A strain measurement technique for studying the strain distribution in polybutylene terephthalate (PBT) has been developed In this study, st rain level lip to 11% was measured by monitoring the reversible confor mational changes of the glycol residue in PET as a function of applied strain. In the unstrained state, the glycol residue is close to gauch e-trans-gauche sequence (phase I) and changes to the all-trans states (phase II) on straining. In both cases, intensities of Raman bands ori ginating from different phases of the glycol residue were either incre ased or decreased The intensity change of these strain-sensitive Raman bands varied linearly with the applied strain. Furthermore, this inte nsity change was recovered as the strain was released. Therefore, we h ave demonstrated that this technique will be useful in analyzing the s train level in PET polymer and its composites. (C) 1998 Elsevier Scien ce Ltd. All rights reserved.