In this paper, carbon fiber and Kevlar R fiber woven composites were investigated as potential cryogenic tank materials for storing liquid fuel in spacecraft or rocket. Towards that end, both carbon and Kevlar R fiber composites were manufactured and tested with and without cryogenic exposure. The focus was on the investigation of the influence of initial cryogenic exposure on the degradation of the composite. Tensile, flexural and inter laminar shear strength (ILSS) tests were conducted, which indicate that Kevlar R and carbon textile composites are potential candidates for use under cryogenic exposure.

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In this paper, the adverse effects of sea water environment and arctic temperatures on woven carbon fiber/vinyl ester composites are explored in the form of moisture uptake, impact on flexural modulus, strength, and structural damage. The research presented here attempts to relate failure modes to the flexural behavior of these composites exposed to three key environmental conditions: sea water, arctic temperature and combined sea water/arctic condition. Sea water saturation in general degrades the flexural strength up to ≈19.45%. Microstructures of dry and saturated samples are compared using scanning electron microscopy, where a saturated surface with distinctive hue for wet samples is observed as compared to a rough (parched) surface in the dry samples, implying large concentrations of sea water in a thin layer at the specimen boundaries. Arctic exposure and combined condition on these laminates increase the flexural strength by about 23.1% and 36.2%, respectively. However, they tend to shift the post peak behavior from progressive to brittle-type failure as compared to dry samples, which is attributed to matrix and fiber embrittlement in the material system caused by exposure to low temperature. Further, relatively large variations are observed in the flexural strength values of samples exposed to the combined condition (sea water saturated + arctic), which can be attributed to the freezing of sea water that was entrapped during sea water saturation. Variation in the quantity and location of sea water entrapped can alter the flexural strength significantly. Due to the aforementioned flexural responses and failure behavior observed in woven carbon/vinyl ester composites exposed to sea water arctic environment, special consideration is required while designing critical load bearing components in naval applications to avoid possible catastrophic structural failure.

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A novel technique to improve the Mode I and Mode II interlaminar fracture toughness of woven carbon-fiber polymer matrix composite face sheets using zinc oxide nanowires is proposed. Zinc oxide nanowires are directionally synthesized on dry carbon fabrics that are used to manufacture the laminate. The influence of zinc oxide nanowires on interlaminar fracture toughness is compared against regular interfaces using double cantilever beam and end-notched flexure tests to provide fracture toughness values. A significant improvement in the Mode I and Mode II interlaminar fracture toughness values is observed with zinc oxide nanowires. Therefore, zinc oxide nanowire interlaminar reinforcement has been proven to enhance the interlaminar fracture toughness of textile composites.