Positron Annihilation Spectroscopy Techniques for Composite Characterization

While the benefits of using composite materials in engineering applications are well known, industry growth has been limited by a number of factors that make it difficult to use composite materials in structural designs. This SBIR program will help address some of these issues by demonstrating the capabilities of positron annihilation spectroscopy (PAS) techniques to (1) monitor the cure of polymer matrix composite materials; (2) assess the effects of processing variables that can lead to decreased performance or service life; and (3) nondestructively evaluate the effects of thermal degradation in a series of polymer matrix composite materials. The application of positron annihilation lifetime spectroscopy (PALS) and Doppler broadening spectroscopy (DBS) will be evaluated in the Phase I SBIR program and Option Task, respectively. Cure monitoring and processing effects will be evaluated using a two-component epoxy resin system. McDonnell Douglas has provided a series of 8 polymer matrix resin systems which have been aged under isothermal (0 to 15,000 hours) and accelerated conditions for the thermal degradation analysis by PAS. The results of this work will clearly demonstrate the capabilities of PAS as a nondestructive technique of materials characterization. The effects of various instrumental variables will be evaluated to generate information that will be important when designing a commercial NDE instrument based on PAS. This portion of the program will provide the basic information needed to develop a successful product commercialization path.