AN INVESTIGATION INTO THE EFFECTS OF GRAFT-POLYMERIZATION OF VINYL MONOMERS TO WOOL

Traditionally, the grafting of vinyl monomers to wool has been used to improve shrinkage, but this has been largely superseded by more effective polymer deposition or interfacial condensation techniques. The grafting of vinyl monomers to wool substrates can, however, have a number of other effects; notably changes in dye uptake, tensile behavior and handle. This work investigates the potential of these side effects, as a method of improving specific fiber properties. In addition, work was carried out with a view towards developing a system of industrial, rather than purely scientific, significance. Several systems for the efficient and selective grafting of vinyl monomers to wool were investigated. A highly efficient and selective system was developed using the redox couple KBrO3 and Co(CH3COO)2.4H2O, with monomers such as methyl-, ethyl- and butyl-methacrylate. The effects of cosolvents such as acetone and diethyleneglycol monobutylether (BC) were also studied. It was found that both dye uptake and tensile strength could be significantly improved by relatively low levels of grafting without deleterious effects on handle. A novel Limiting Volume model was developed to describe the various stages through which the grafting process proceeds, based on dye uptake, tensile strength, Scanning Electron Microscopy (SEM) and homopolymer content. This model satisfactorily explains the observed results, particularly at high levels of grafting where polymer growth is forced onto the fiber surface.