Where "Q" _"t" is the mole of water uptake by 100 g of polymer composites, "M" _"e" (w) is the mass of water at a given time, "M" _"r" (w) is the relative molecular mass of water, and "M" _"I" (S) is the initial mass of the sample. At equilibrium, "Q" _"t" is equal to "Q" _∞, which is mole of water uptake by 100 g of polymer composites at infinite time.