Graft-copolymerization of acrylic acid and n-vinyl 2-pyrrolidone onto polypropylene fibres

Graft-copolymerization of acrylic acid and N-vinyl 2-pyrrolidone into polypropylene fibres had been carried out by using trapped radicals as initiator. This method was chosen for the reason that the formation of homopolymer can be eliminated completely. Trapped radicals can be produced by irradiating samples of polypropylene fibres under vacuum. The influence of irradiation dose, time of polymerization and concentration of monomers on the degree of grafting, moisture regain and dye ability have been studied. The grafting process was carried out by using solution of acrylic acid or N-vinyl 2-pyrrolidone in water under vacuum. Salt of cupric acetate have been used for inhibiting the formation of homopolymer. The results, polypropylene-acrylic acid grafted was converted into salt of sodium for increasing its melting point. A degree of grafting between 15% and 30% shows the excellent moisture regain and dye-ability. For that purpose, an irradiation dose between 0,33 and 0,99 Mrad (electron or gamma) was needed. Optimum time of grafting was about two hours in the case of N-vinyl 2-pyrrolidone solution and one hour in the case of acrylic acid solution. Temperature of grafting was selected 60degC. (author)