AbstractIn this study the effect of virgin and recycled plastics on water absorption of nanocomposites from newsprint fiber and organoclay was studied. Newsprint fiber was mixed with either virgin or recycled polypropylene (PP) at 30% by weight fiber loading. The samples were made by melt compounding and then injection molding. The concentration was varied as 0, 2.5, and 5% for nanoclay. The amount of coupling agent was fixed at 10% for all formulations. The long-term water absorptions of samples were evaluated by immersing them in water at room temperature for several weeks, and water diffusion coefficients were also calculated by evaluating the water absorption isotherms. The results indicated that whether or not virgin plastic is used has a significant effect on the water absorption of composites. The water absorption of the newsprint fiber/recycled plastic composites was higher than those of virgin plastics. Furthermore, with addition of nanoclay content in composites, water absorption decreased. Water absorption of all formulations was proved to follow the kinetics of a Fickian diffusion process. Morphological findings showed the formation of intercalated morphology and better dispersion with 2.5% of nanoclay.