Grafting vinyl monomers onto silk fibers. IX. Graft copolymerization of methyl methacrylate onto silk using peroxydiphosphate‐thiourea redox system

The graft copolymerization of methyl methacrylate (MMA) onto silk in aqueous media initiated by the potassium peroxydiphosphate‐thiourea redox system was studied at 50°C. The rate of grafting was determined by changing [monomerl], [thiourea], [initiator], acidity of the medium, reaction medium, and temperature. A significant increase percent of grafting was noticed with increasing monomer concentration to 84.49 × 10 −2 mole/liter and the further increase is associated with the decrease of graft yield. The graft yield increases with an increase of thiourea (Tu) concentration to 25 × 10 −5 mole/liter; then it decreases. A measurable increase in graft yield was observed with an increase in acidity of the medium. Graft yield increases to a certain temperature, i.e., 50°C, and then it decreases. The graft yield increases with an increase of initiator concentration to 60 × 10 −4 mole/liter; then it decreases. The graft yield is medium dependent. A suitable kinetic path has been proposed and the rate equation has been derived.