Effect of void content on the moisture absorption in polymeric composites

This study assesses the effect of porosity in the moisture absorption of polymeric composites. The preparation of composites samples with porosity, control, and measurement of void content, and moisture absorption behavior of carbon/epoxy laminates are discussed. Rheological analyses are used to characterize the viscosity behavior of prepregs either in the presence or absence of moisture. Polymeric composites with different levels of voids were produced and submitted to hygrothermal conditioning to study the moisture absorption behavior. It was found that the rate of water uptake and the maximum level of moisture absorption in carbon/epoxy composites depends on the void content and specimen geometry. The dependence on the void content may be quite significant. The nature of the matrix system was also verified to affect the moisture absorption properties of the composite.