Diffusion and Copolymerization of Polyacrylic Acid in Nylon 66 Fibers

Abstract

Polyacrylic acid (PAA) was applied to a plain-weave nylon 66 fabric from solution at an elevated temperature and pressure. Excess solution was squeezed out and the fabric was oven-dried, heat-cured, and hot water-scoured. The weight of PAA, up to 6% fixed to the nylon, varied inversely with the pH of the PAA solution. Cured fabric with 6% fixed PAA, when converted to the sodium and potassium salts, had moisture regain values comparable to those for cotton. The calcium salt increased the melting temperature of the nylon. Cross sections, of yarns teased from this fabric, stained with a cationic dye revealed that PAA had penetrated the in dividual fibers. This type of polymer diffusion has not been reported previously. The PAA-nylon product isolated from the cured fabric differed from the reactants in solubility, thermal characteristics, and ir absorption. These facts suggest that the PAA had reacted chemically with the nylon. Less PAA reacted when the amine end groups of nylon were blocked, indicating that, in addition to a block copolymer, a graft copolymer formed.