Studies on graft copolymerization of methyl methacrylate onto chemically modified tussa silk fibers. Peroxydisulfate‐thiourea redox system

Abstract

The graft copolymerization of methyl methacrylate (MMA) onto chemically modified tussa silk fibers in aqueous media using potassium peroxodisulfate-thiourea redox initiator system was studied at 60°C. The effects of time of reaction, concentrations of oxidant, thiourea (TU), monomer (M), amount of silk fibers on graft yield have been studied. The effects of reaction medium, acid concentration, and some inorganic salts and organic solvents on grafting have also been investigated. A significant increase in percent of grafting was observed with increasing monomer concentration to 65.86 * lo-* mole 1-' ; a further increase of monomer concentration is associated with the decrease of graft yield. The graft yield increases with an increase of thiourea concentration up to 10. lo-' mol * 1-' , beyond which it decreases very significantly. A measurable increase of the graft yield was also observed with an increase of the oxidant concentration up to 0.08 mole 1-' beyond which the graft yield decreased. The graft yield was medium dependent. The reaction mechanism of the grafting process has been proposed and a rate expression has been derived on the basis of experimental findings. IR spectra of the grafted fiber and original fiber have been taken and their characteristic bands have been identified. The thermal behaviour of the original and grafted silk fibers has been studied by TGA and DTG analysis. Grafting has improved thermal stability as well as the light fastness of silk dyed with Rhodamine B. 0 1987 Hiithig& Wepf Verlag, Basel 0003-3146/87/$03.00IR-Spektren der gepfropften und Originalfasern aufgenommen und ihre charakteristischen Banden identifiziert. Das thermische Verhalten der Original-und gepfropften Fasern wurde mit Hilfe der Thermoanalyse ermittelt. Das Pfropfen erhdhte sowohl die thermische Stabilitat a k auch die Lichtbestandigkeit der Seide, die mit Rhodamin B gefiirbt war.

Photograft copolymerization of methyl methacrylate on silk fiber using titanium(III) chloride-potassium persulphate redox initiator in a limited aqueous system. I

“…Many workers [5][6][7] have reported the use of metal acetylacetonate for graft copolymerization of vinyl monomers on silk. The use of K 2 S 2 O 8 -thiourea as a redox initiator 8 and the SO 2 -isoquinoline charge transfer complex as a photoinitiator 9 have also been reported. However, only limited information regarding grafting of vinyl monomers onto silk under visible light is available.…”