抄録
Untreated and heat-treated (at 180°C or 225°C) polyvinyl alcohol (PVA) fibers imbibing solutions (1g/g-fiber) of various catalysts were heated with styrene (1.8g/g-fiber) in sealed tubes for graft polymerization. When potassium or ammonium persulfate were used as catalysts, the grafting generally proceeded smoothly, and the graft efficiencies of about 90% were obtained under suitable conditions. The graft efficiencies were affected only a little by catalyst concentrations (0.3_??_3%), solvents (water, water 15-methanol 85, water 30-acetone 70) of the imbibing solutions, and heating temperatures. In the cases of hydrogen peroxide, the graft efficiencies were generally lower than those in the cases of persulfates, but the efficiencies of about 80% were obtained under favorable conditions. The graft efficiencies increased with decreasing catalyst concentrations and heating tempratures, and increasing water contents of the imbibing solutions. In the cases of α, α′-azo-bisisobutyronitrile and benzoyl peroxide, the grafting did not proceed so smoothly as in the cases of persulfates; the efficiencies were only about 55% even under favorable conditions, and the efficiencies were affected considerably by catalyst concentrations and heating temperatures.
The grafting was affected only a little by previous heat treatment of the fiber so far as the water contents of imbibing solutions were high, but considerably affected when the water contents were lower.
As the other series of experiments, dry PVA fibers imbibing catalysts were heated with styrenemethanol mixtures for the grafting, and it was found that the reaction proceeded as smoothly as with fibers imbibing catalyst solutions. But, the grafting scarcely proceeded when dry fibers were heated with pure styrene.
Graft polymerization of styrene in emulsion states onto PVA fibers were also investigated, The grafting of high efficiencies could be obtained using 2% polyethylene glycol oleyl ether as an emulsifier.
The grafting behaviors of the PVA-styrene system were generally similar to those of the cellulose-styrene system, but some small differences were found between them.
