Mechanical strength retention and service life of Kevlar fiber woven mat reinforced epoxy laminated composites for structural applications

This work investigates the diffusivity, long-term tensile performance and prediction of service life of Kevlar fiber woven mat reinforced epoxy laminated composites (KFMRELC). The composites were prepared by hand layup method with compression molding process. The tensile test was conducted on dry and aged composites as per ASTM D 638 standard. These composites were immersed in water at various temperatures of 20 degrees C, 40 degrees C and 60 degrees C and various time periods. The diffusivity was calculated by Fick's law. The activation energy and service life were calculated by Arrhenius principle. In results, the tensile strength was gradually decreased by increasing the immersion time, and the maximum reduction was found at 60 degrees C and 300 days due to loss of bonding between the fiber and matrix. Increasing the aging temperature was decreased bonding between the fiber and matrix which reduced the tensile strength. Therefore, the KFMRELC composite retained long life and exhibited less reduction in tensile stress at 20 degrees C environment. Considering 80% of tensile strength retention, the life of KFMRELC composite was found 50 year less at higher temperature because the rate of diffusivity and degradation were found higher. Hence, the maximum tensile strength retention was showed for 50 years. Based on the life cycle curve, the KFMRELC composite can be selected for suitable applications.