GRAFT-COPOLYMERIZATION OF BENZYL METHACRYLATE ONTO WOOL FIBERS

Benzyl methacrylate (BzMA) was graft copolymerized onto wool fibers by using ammonium peroxydisulphate as the initiator. Grafted samples wit h different polymer add ons (from 7 to 180%) were obtained by varying the monomer concentration in the reaction system. Following grafting w ith BzMA, the X-ray diffraction peak at 20.2 degrees slightly moved to wards higher spacing values. Birefringence decreased, indicating a low er degree of molecular orientation of grafted wool fibers. The equilib rium regain values of grafted wool decreased with increasing add on. T ensile strength increased in the range 45-77% add on, while elongation at break. decreased. Differential scanning calorimetry (DSC) and ther mogravimetry (TG) measurements showed a higher thermal stability for g rafted wool. Following grafting, the drop of dynamic storage modulus ( E') shifted to a lower temperature. Accordingly, tile intensity of the loss modulus (E'') peak decreased, indicating that the thermally indu ced molecular motion was enhanced by grafting. Thermomechanical analys is (TMA) confirmed the increase in chain mobility for the grafted wool fibers. Above 35-40% add ion, the presence of homopolymer on the surf ace of the wool fibers was identified by scanning electron microscopy. (C) 1997 John Wiley & Sons, Inc.