Grafting of polyester fabrics with methacrylic acid

Modification of polyester (poly(ethylene terephthalate)) fabric by grafting with poly(methacrylic acid) was studied. The objective was to improve the hydrophilicity of polyester and, hence, its water uptake. The modified polyester fabrics were characterized by gravimetric method, Fourier transform infrared, dynamic mechanical analysis, and scanning electron microscopy. It was found that grafting of methacrylic acid onto polyester fabrics could be effected by radical reaction using benzoyl peroxide as radical initiator. Swelling of polyester fabric with benzyl alcohol was also found to be necessary for grafting to occur. The parameters which affected the modification reaction were initiator concentration, monomer to fabric ratio, reaction temperature, and reaction time. In addition, it was shown that the percentage uptake of moisture of the modified fabric (1–4.6%) increased with increase in the extent of grafting (5–32%). The modified fabric tended to be stiffer than the unmodified fabric, but they could be softened by controlled treatment with aqueous solution of sodium hydroxide. The stability of the modified polyester fabric, however, was found to decrease with increase in the extent of modification (high monomer to fabric ratio) and increasing concentration of sodium hydroxide solution. Thus, careful control of sodium hydroxide treatment process was necessary to prevent deterioration of the modified polyester fabric.