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Increasing Strengths of Boron Fiber and Graphite Fiber Plastic Composites.
Final rept. May-Dec 71,
NORTHROP CORPORATE LABS HAWTHORNE CA
Pagination or Media Count:
Prestressing of boronepoxy prepreg tape material yields com-posites with substantial improvements in both average tensile strength and standard deviation over that obtained with conven-tional prepreg to laminate processing. The process has a fundamental effect on the prepreg fiber strength properties by prebreaking the fibers at their weak sites, and these induced changes are then carried into the composite as a reduction in property dispersion. The effects of processing parameters are evaluated by characterizing the details in the fiber strength distributions. The induced changes in fiber strength distri-bution are correlated with the composite strength properties. Prestressing essentially performs a quality control function on commerical type prepreg by reducing the inherent variability of unprocessed material. Fracture mode control has also been demonstrated for boron polyimide systems by a laminating method of alternating layers of resin rich and fiber rich prepreg mater-ial. Author, modified-PL
APPROVED FOR PUBLIC RELEASE