Mechanical performance of interply hybrid composites submitted to wet environments and petroleum

The mechanical properties of polymer composites under the influence of external agents (heat, temperature, contact fluids) have been investigated in several industrial areas, such as aerospace, automotive, and petroleum. This study aimed to explore the relationship between environmental exposure and mechanical properties, given its impact on the final mechanical performance, service life, and industrial applications of reinforced composites. In the present study, three laminate plates with a polymeric matrix were manufactured, and reinforced with bidirectional E-glass fiber and Kevlar-49 fabric. The laminates were industrially produced using a hand lay-up process and immersed in fluids (crude oil and seawater) to investigate the relationship between fluid immersion and mechanical properties, highlighting the effects observed under the imposed conditions, apparent morphology, the microstructure of post-immersed samples, and final mechanical performance. Comparative results (dry vs wet) demonstrated that fluid contact did not significantly reduce strength, except for the IGK laminate, which showed a 19% reduction when immersed in petroleum and tested under bending, all other values remained below 10%. However, the losses in elastic modulus were more significant, reaching up to 50% rigidity loss in some cases. Morphological analysis showed resin degradation and petroleum impregnation due to chloride ions from seawater and crude oil exposure.