Review 32 Bull. N RC, Egypr, 24, No.4 ,pp.495- 515 (1999) A Review on Chemical Modification and Dyeability of Acrylic Fibres A. Bendak and L. EL - Gabry Textile Research Division, National Research Centre .Dokki, Cairo, Egypt. A review on acryli c fibres is given illo strating their modltlcations either chemically or hy th ermal tr eatments , Impr ovem ent of water absorption capacity and dyeabiJity of the fibres are reputed . Vari ous asp ects uf dyeing of acrylic fibre s with ca tionic, reactive, acid and di sperse dyestuffs arc also present ed. Key Words : Acrylic fibre s. Chemi cal modification . Thermal treatment. Dycabiluy Acrylic fibres have important position in the textile industry and , there is al way s a con tinuous increase in the product ion and con sumpti on of th ese fibres . In the present review, it is intended to focu s on rhe pri vileg e of modifying acrylic fibres chemi cally or via thermal tre atment s in order to attain some advancement in its wet properties especiall y dyeability. Chemical Composition Acr ylic fibr es are mainly c omp o sed of poly (acrylonitrile) which IS prepared by polymerization of acrylonitrile molecules (J ) . n CH 2 = CH I CN The term "Acrylic fibres" refers to those fibres which contain more than 85% acrylonitrile units, (CH 2 = CH- CN). Most acrylic fibres are made from copolymers including one or more m onomers in addition to acrylonitrile (2). Su ch monomers are some ethylene deri vatives, vinyl acetate, methacrylate, styrene, acrylamide, 2- vinylpyridine, 2- methyl - 5 - vinylpyridine, acrylic acid, rnethacrylic acid or itaconic acid (I ) . The common comonomers having affinity for acid dy estuffs are vinyl pyridine and methyl vinyl pyridine. The ratio of the se comonomers in polyacrylonitrile range s from 2 to 5 % (3) . 2 CH2 = CH + CH2= CH - CH2 - CH ---- CH') - CH- CH 2 - CH IN 6 L -6 leN N N . "