The strength, fracture, and chemical interactions between poly(p-phenylene benzobisthiazole) fiber or film after elevated temperature exposure to aluminum

Tensile properties, fracture behavior, surface chemical composition, and interfacial structures poly-(p-phenylene benzobisthiazole) or PBZT, fibers have been measured as a function of contact with molten aluminum overlayers. After five minutes immersion at 600{dollar}spcirc{dollar} and 700{dollar}spcirc{dollar}C in a molten aluminum alloy, strengths dropped to 80% and 25% of the uncoated fiber values, respectively.; Photoelectron Spectroscopy of the polymer surface indicates that oxidation has occurred during fabrication. The oxygen content of the surface is decreased but not totally lost when the film is immersed in aluminum-silicon alloy, suggesting that the oxidized layer plays some role in protecting the polymer from degradation.; Interfacial structure and chemical profiles of PBZT fibers indicate depletion of sulfur within the polymer as a result of contact with molten aluminum. Microvoids were observed at the metal/polymer interface for samples heated at 600{dollar}spcirc{dollar}C for times of 30 to 60 minutes.; PBZT strength loss after immersion is due primarily to degradation of the polymer molecular structure via chain scission reducing the polymer's molecular weight. Molten aluminum accelerates the degradation of the fiber, due to the large concentration gradient for elements in PBZT relative to the molten aluminum.; These results strongly suggest the possibility of fabricating low-density, high-strength polymer-metal composites by liquid aluminum-alloy infiltration utilizing PBZT fibers, if the melt temperature is kept below 680{dollar}spcirc{dollar}C and the contact time kept below 3 minutes.