STUDY OF DIELECTRIC RESPONSE OF PMR-15 RESIN DURING CURE

Up to now, no technique is available to allow non-destructive, in situ , characterization of the polymerization during the curing of a thermo set resin. Dynamic dielectric measurements made over a wide range of f requencies would have the potential to provide a sensitive and conveni ent control of follow-up of both imidization and cross-linking of PMR- 15 resin. This dynamical study is based on dielectric analysis of two model compounds NE-MDA-NE and 3MDA-2BTDE. A new experimental method is described to follow up PMR-15 polymerization by using de measurements . Dynamic mechanical analysis using the same cure cycles as dielectrom etric measurements were also carried out. Electric and mechanical meas urements were correlated and the results on the model compounds extend ed to the analysis of PMR-15 resin present good agreement of the varia tions of ionic conductivity with mechanical modulus during cure. Based on these results, cure monitoring of PMR-15 prepreg is possible by us ing microdielectrometry; in particular, dielectric events can be corre lated to mechanical phenomena.